Move bundled copy of sqlite one level deeper to better separate it...

third_party/sqlite/src/vdbeaux.c

-/*
-** 2003 September 6
-**
-** The author disclaims copyright to this source code.  In place of
-** a legal notice, here is a blessing:
-**
-**    May you do good and not evil.
-**    May you find forgiveness for yourself and forgive others.
-**    May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This file contains code used for creating, destroying, and populating
-** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
-** to version 2.8.7, all this code was combined into the vdbe.c source file.
-** But that file was getting too big so this subroutines were split out.
-**
-** $Id: vdbeaux.c,v 1.480 2009/08/08 18:01:08 drh Exp $
-*/
-#include "sqliteInt.h"
-#include "vdbeInt.h"
-
-
-
-/*
-** When debugging the code generator in a symbolic debugger, one can
-** set the sqlite3VdbeAddopTrace to 1 and all opcodes will be printed
-** as they are added to the instruction stream.
-*/
-#ifdef SQLITE_DEBUG
-int sqlite3VdbeAddopTrace = 0;
-#endif
-
-
-/*
-** Create a new virtual database engine.
-*/
-Vdbe *sqlite3VdbeCreate(sqlite3 *db){
-  Vdbe *p;
-  p = sqlite3DbMallocZero(db, sizeof(Vdbe) );
-  if( p==0 ) return 0;
-  p->db = db;
-  if( db->pVdbe ){
-    db->pVdbe->pPrev = p;
-  }
-  p->pNext = db->pVdbe;
-  p->pPrev = 0;
-  db->pVdbe = p;
-  p->magic = VDBE_MAGIC_INIT;
-  return p;
-}
-
-/*
-** Remember the SQL string for a prepared statement.
-*/
-void sqlite3VdbeSetSql(Vdbe *p, const char *z, int n, int isPrepareV2){
-  if( p==0 ) return;
-#ifdef SQLITE_OMIT_TRACE
-  if( !isPrepareV2 ) return;
-#endif
-  assert( p->zSql==0 );
-  p->zSql = sqlite3DbStrNDup(p->db, z, n);
-  p->isPrepareV2 = isPrepareV2 ? 1 : 0;
-}
-
-/*
-** Return the SQL associated with a prepared statement
-*/
-const char *sqlite3_sql(sqlite3_stmt *pStmt){
-  Vdbe *p = (Vdbe *)pStmt;
-  return (p->isPrepareV2 ? p->zSql : 0);
-}
-
-/*
-** Swap all content between two VDBE structures.
-*/
-void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
-  Vdbe tmp, *pTmp;
-  char *zTmp;
-  tmp = *pA;
-  *pA = *pB;
-  *pB = tmp;
-  pTmp = pA->pNext;
-  pA->pNext = pB->pNext;
-  pB->pNext = pTmp;
-  pTmp = pA->pPrev;
-  pA->pPrev = pB->pPrev;
-  pB->pPrev = pTmp;
-  zTmp = pA->zSql;
-  pA->zSql = pB->zSql;
-  pB->zSql = zTmp;
-  pB->isPrepareV2 = pA->isPrepareV2;
-}
-
-#ifdef SQLITE_DEBUG
-/*
-** Turn tracing on or off
-*/
-void sqlite3VdbeTrace(Vdbe *p, FILE *trace){
-  p->trace = trace;
-}
-#endif
-
-/*
-** Resize the Vdbe.aOp array so that it is at least one op larger than 
-** it was.
-**
-** If an out-of-memory error occurs while resizing the array, return
-** SQLITE_NOMEM. In this case Vdbe.aOp and Vdbe.nOpAlloc remain 
-** unchanged (this is so that any opcodes already allocated can be 
-** correctly deallocated along with the rest of the Vdbe).
-*/
-static int growOpArray(Vdbe *p){
-  VdbeOp *pNew;
-  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
-  pNew = sqlite3DbRealloc(p->db, p->aOp, nNew*sizeof(Op));
-  if( pNew ){
-    p->nOpAlloc = sqlite3DbMallocSize(p->db, pNew)/sizeof(Op);
-    p->aOp = pNew;
-  }
-  return (pNew ? SQLITE_OK : SQLITE_NOMEM);
-}
-
-/*
-** Add a new instruction to the list of instructions current in the
-** VDBE.  Return the address of the new instruction.
-**
-** Parameters:
-**
-**    p               Pointer to the VDBE
-**
-**    op              The opcode for this instruction
-**
-**    p1, p2, p3      Operands
-**
-** Use the sqlite3VdbeResolveLabel() function to fix an address and
-** the sqlite3VdbeChangeP4() function to change the value of the P4
-** operand.
-*/
-int sqlite3VdbeAddOp3(Vdbe *p, int op, int p1, int p2, int p3){
-  int i;
-  VdbeOp *pOp;
-
-  i = p->nOp;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  assert( op>0 && op<0xff );
-  if( p->nOpAlloc<=i ){
-    if( growOpArray(p) ){
-      return 1;
-    }
-  }
-  p->nOp++;
-  pOp = &p->aOp[i];
-  pOp->opcode = (u8)op;
-  pOp->p5 = 0;
-  pOp->p1 = p1;
-  pOp->p2 = p2;
-  pOp->p3 = p3;
-  pOp->p4.p = 0;
-  pOp->p4type = P4_NOTUSED;
-  p->expired = 0;
-#ifdef SQLITE_DEBUG
-  pOp->zComment = 0;
-  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
-#endif
-#ifdef VDBE_PROFILE
-  pOp->cycles = 0;
-  pOp->cnt = 0;
-#endif
-  return i;
-}
-int sqlite3VdbeAddOp0(Vdbe *p, int op){
-  return sqlite3VdbeAddOp3(p, op, 0, 0, 0);
-}
-int sqlite3VdbeAddOp1(Vdbe *p, int op, int p1){
-  return sqlite3VdbeAddOp3(p, op, p1, 0, 0);
-}
-int sqlite3VdbeAddOp2(Vdbe *p, int op, int p1, int p2){
-  return sqlite3VdbeAddOp3(p, op, p1, p2, 0);
-}
-
-
-/*
-** Add an opcode that includes the p4 value as a pointer.
-*/
-int sqlite3VdbeAddOp4(
-  Vdbe *p,            /* Add the opcode to this VM */
-  int op,             /* The new opcode */
-  int p1,             /* The P1 operand */
-  int p2,             /* The P2 operand */
-  int p3,             /* The P3 operand */
-  const char *zP4,    /* The P4 operand */
-  int p4type          /* P4 operand type */
-){
-  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
-  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
-  return addr;
-}
-
-/*
-** Create a new symbolic label for an instruction that has yet to be
-** coded.  The symbolic label is really just a negative number.  The
-** label can be used as the P2 value of an operation.  Later, when
-** the label is resolved to a specific address, the VDBE will scan
-** through its operation list and change all values of P2 which match
-** the label into the resolved address.
-**
-** The VDBE knows that a P2 value is a label because labels are
-** always negative and P2 values are suppose to be non-negative.
-** Hence, a negative P2 value is a label that has yet to be resolved.
-**
-** Zero is returned if a malloc() fails.
-*/
-int sqlite3VdbeMakeLabel(Vdbe *p){
-  int i;
-  i = p->nLabel++;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  if( i>=p->nLabelAlloc ){
-    int n = p->nLabelAlloc*2 + 5;
-    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel,
-                                       n*sizeof(p->aLabel[0]));
-    p->nLabelAlloc = sqlite3DbMallocSize(p->db, p->aLabel)/sizeof(p->aLabel[0]);
-  }
-  if( p->aLabel ){
-    p->aLabel[i] = -1;
-  }
-  return -1-i;
-}
-
-/*
-** Resolve label "x" to be the address of the next instruction to
-** be inserted.  The parameter "x" must have been obtained from
-** a prior call to sqlite3VdbeMakeLabel().
-*/
-void sqlite3VdbeResolveLabel(Vdbe *p, int x){
-  int j = -1-x;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  assert( j>=0 && j<p->nLabel );
-  if( p->aLabel ){
-    p->aLabel[j] = p->nOp;
-  }
-}
-
-#ifdef SQLITE_DEBUG
-
-/*
-** The following type and function are used to iterate through all opcodes
-** in a Vdbe main program and each of the sub-programs (triggers) it may 
-** invoke directly or indirectly. It should be used as follows:
-**
-**   Op *pOp;
-**   VdbeOpIter sIter;
-**
-**   memset(&sIter, 0, sizeof(sIter));
-**   sIter.v = v;                            // v is of type Vdbe* 
-**   while( (pOp = opIterNext(&sIter)) ){
-**     // Do something with pOp
-**   }
-**   sqlite3DbFree(v->db, sIter.apSub);
-** 
-*/
-typedef struct VdbeOpIter VdbeOpIter;
-struct VdbeOpIter {
-  Vdbe *v;                   /* Vdbe to iterate through the opcodes of */
-  SubProgram **apSub;        /* Array of subprograms */
-  int nSub;                  /* Number of entries in apSub */
-  int iAddr;                 /* Address of next instruction to return */
-  int iSub;                  /* 0 = main program, 1 = first sub-program etc. */
-};
-static Op *opIterNext(VdbeOpIter *p){
-  Vdbe *v = p->v;
-  Op *pRet = 0;
-  Op *aOp;
-  int nOp;
-
-  if( p->iSub<=p->nSub ){
-
-    if( p->iSub==0 ){
-      aOp = v->aOp;
-      nOp = v->nOp;
-    }else{
-      aOp = p->apSub[p->iSub-1]->aOp;
-      nOp = p->apSub[p->iSub-1]->nOp;
-    }
-    assert( p->iAddr<nOp );
-
-    pRet = &aOp[p->iAddr];
-    p->iAddr++;
-    if( p->iAddr==nOp ){
-      p->iSub++;
-      p->iAddr = 0;
-    }
-  
-    if( pRet->p4type==P4_SUBPROGRAM ){
-      int nByte = (p->nSub+1)*sizeof(SubProgram*);
-      int j;
-      for(j=0; j<p->nSub; j++){
-        if( p->apSub[j]==pRet->p4.pProgram ) break;
-      }
-      if( j==p->nSub ){
-        p->apSub = sqlite3DbReallocOrFree(v->db, p->apSub, nByte);
-        if( !p->apSub ){
-          pRet = 0;
-        }else{
-          p->apSub[p->nSub++] = pRet->p4.pProgram;
-        }
-      }
-    }
-  }
-
-  return pRet;
-}
-
-/*
-** Check if the program stored in the VM associated with pParse may
-** throw an ABORT exception (causing the statement, but not transaction
-** to be rolled back). This condition is true if the main program or any
-** sub-programs contains any of the following:
-**
-**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
-**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
-**   *  OP_Destroy
-**   *  OP_VUpdate
-**   *  OP_VRename
-**
-** Then check that the value of Parse.mayAbort is true if an
-** ABORT may be thrown, or false otherwise. Return true if it does
-** match, or false otherwise. This function is intended to be used as
-** part of an assert statement in the compiler. Similar to:
-**
-**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
-*/
-int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
-  int hasAbort = 0;
-  Op *pOp;
-  VdbeOpIter sIter;
-  memset(&sIter, 0, sizeof(sIter));
-  sIter.v = v;
-
-  while( (pOp = opIterNext(&sIter))!=0 ){
-    int opcode = pOp->opcode;
-    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
-     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
-      && (pOp->p1==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
-    ){
-      hasAbort = 1;
-      break;
-    }
-  }
-  sqlite3DbFree(v->db, sIter.apSub);
-
-  /* Return true if hasAbort==mayAbort. Or if a malloc failure occured.
-  ** If malloc failed, then the while() loop above may not have iterated
-  ** through all opcodes and hasAbort may be set incorrectly. Return
-  ** true for this case to prevent the assert() in the callers frame
-  ** from failing.  */
-  return ( v->db->mallocFailed || hasAbort==mayAbort );
-}
-#endif
-
-/*
-** Loop through the program looking for P2 values that are negative
-** on jump instructions.  Each such value is a label.  Resolve the
-** label by setting the P2 value to its correct non-zero value.
-**
-** This routine is called once after all opcodes have been inserted.
-**
-** Variable *pMaxFuncArgs is set to the maximum value of any P2 argument 
-** to an OP_Function, OP_AggStep or OP_VFilter opcode. This is used by 
-** sqlite3VdbeMakeReady() to size the Vdbe.apArg[] array.
-*/
-static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
-  int i;
-  int nMaxArgs = *pMaxFuncArgs;
-  Op *pOp;
-  int *aLabel = p->aLabel;
-  p->readOnly = 1;
-  for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){
-    u8 opcode = pOp->opcode;
-
-    if( opcode==OP_Function || opcode==OP_AggStep ){
-      if( pOp->p5>nMaxArgs ) nMaxArgs = pOp->p5;
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    }else if( opcode==OP_VUpdate ){
-      if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
-#endif
-    }else if( opcode==OP_Transaction && pOp->p2!=0 ){
-      p->readOnly = 0;
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    }else if( opcode==OP_VFilter ){
-      int n;
-      assert( p->nOp - i >= 3 );
-      assert( pOp[-1].opcode==OP_Integer );
-      n = pOp[-1].p1;
-      if( n>nMaxArgs ) nMaxArgs = n;
-#endif
-    }
-
-    if( sqlite3VdbeOpcodeHasProperty(opcode, OPFLG_JUMP) && pOp->p2<0 ){
-      assert( -1-pOp->p2<p->nLabel );
-      pOp->p2 = aLabel[-1-pOp->p2];
-    }
-  }
-  sqlite3DbFree(p->db, p->aLabel);
-  p->aLabel = 0;
-
-  *pMaxFuncArgs = nMaxArgs;
-}
-
-/*
-** Return the address of the next instruction to be inserted.
-*/
-int sqlite3VdbeCurrentAddr(Vdbe *p){
-  assert( p->magic==VDBE_MAGIC_INIT );
-  return p->nOp;
-}
-
-/*
-** This function returns a pointer to the array of opcodes associated with
-** the Vdbe passed as the first argument. It is the callers responsibility
-** to arrange for the returned array to be eventually freed using the 
-** vdbeFreeOpArray() function.
-**
-** Before returning, *pnOp is set to the number of entries in the returned
-** array. Also, *pnMaxArg is set to the larger of its current value and 
-** the number of entries in the Vdbe.apArg[] array required to execute the 
-** returned program.
-*/
-VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
-  VdbeOp *aOp = p->aOp;
-  assert( aOp && !p->db->mallocFailed );
-
-  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
-  assert( p->aMutex.nMutex==0 );
-
-  resolveP2Values(p, pnMaxArg);
-  *pnOp = p->nOp;
-  p->aOp = 0;
-  return aOp;
-}
-
-/*
-** Add a whole list of operations to the operation stack.  Return the
-** address of the first operation added.
-*/
-int sqlite3VdbeAddOpList(Vdbe *p, int nOp, VdbeOpList const *aOp){
-  int addr;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  if( p->nOp + nOp > p->nOpAlloc && growOpArray(p) ){
-    return 0;
-  }
-  addr = p->nOp;
-  if( ALWAYS(nOp>0) ){
-    int i;
-    VdbeOpList const *pIn = aOp;
-    for(i=0; i<nOp; i++, pIn++){
-      int p2 = pIn->p2;
-      VdbeOp *pOut = &p->aOp[i+addr];
-      pOut->opcode = pIn->opcode;
-      pOut->p1 = pIn->p1;
-      if( p2<0 && sqlite3VdbeOpcodeHasProperty(pOut->opcode, OPFLG_JUMP) ){
-        pOut->p2 = addr + ADDR(p2);
-      }else{
-        pOut->p2 = p2;
-      }
-      pOut->p3 = pIn->p3;
-      pOut->p4type = P4_NOTUSED;
-      pOut->p4.p = 0;
-      pOut->p5 = 0;
-#ifdef SQLITE_DEBUG
-      pOut->zComment = 0;
-      if( sqlite3VdbeAddopTrace ){
-        sqlite3VdbePrintOp(0, i+addr, &p->aOp[i+addr]);
-      }
-#endif
-    }
-    p->nOp += nOp;
-  }
-  return addr;
-}
-
-/*
-** Change the value of the P1 operand for a specific instruction.
-** This routine is useful when a large program is loaded from a
-** static array using sqlite3VdbeAddOpList but we want to make a
-** few minor changes to the program.
-*/
-void sqlite3VdbeChangeP1(Vdbe *p, int addr, int val){
-  assert( p!=0 );
-  assert( addr>=0 );
-  if( p->nOp>addr ){
-    p->aOp[addr].p1 = val;
-  }
-}
-
-/*
-** Change the value of the P2 operand for a specific instruction.
-** This routine is useful for setting a jump destination.
-*/
-void sqlite3VdbeChangeP2(Vdbe *p, int addr, int val){
-  assert( p!=0 );
-  assert( addr>=0 );
-  if( p->nOp>addr ){
-    p->aOp[addr].p2 = val;
-  }
-}
-
-/*
-** Change the value of the P3 operand for a specific instruction.
-*/
-void sqlite3VdbeChangeP3(Vdbe *p, int addr, int val){
-  assert( p!=0 );
-  assert( addr>=0 );
-  if( p->nOp>addr ){
-    p->aOp[addr].p3 = val;
-  }
-}
-
-/*
-** Change the value of the P5 operand for the most recently
-** added operation.
-*/
-void sqlite3VdbeChangeP5(Vdbe *p, u8 val){
-  assert( p!=0 );
-  if( p->aOp ){
-    assert( p->nOp>0 );
-    p->aOp[p->nOp-1].p5 = val;
-  }
-}
-
-/*
-** Change the P2 operand of instruction addr so that it points to
-** the address of the next instruction to be coded.
-*/
-void sqlite3VdbeJumpHere(Vdbe *p, int addr){
-  sqlite3VdbeChangeP2(p, addr, p->nOp);
-}
-
-
-/*
-** If the input FuncDef structure is ephemeral, then free it.  If
-** the FuncDef is not ephermal, then do nothing.
-*/
-static void freeEphemeralFunction(sqlite3 *db, FuncDef *pDef){
-  if( ALWAYS(pDef) && (pDef->flags & SQLITE_FUNC_EPHEM)!=0 ){
-    sqlite3DbFree(db, pDef);
-  }
-}
-
-/*
-** Delete a P4 value if necessary.
-*/
-static void freeP4(sqlite3 *db, int p4type, void *p4){
-  if( p4 ){
-    switch( p4type ){
-      case P4_REAL:
-      case P4_INT64:
-      case P4_MPRINTF:
-      case P4_DYNAMIC:
-      case P4_KEYINFO:
-      case P4_INTARRAY:
-      case P4_KEYINFO_HANDOFF: {
-        sqlite3DbFree(db, p4);
-        break;
-      }
-      case P4_VDBEFUNC: {
-        VdbeFunc *pVdbeFunc = (VdbeFunc *)p4;
-        freeEphemeralFunction(db, pVdbeFunc->pFunc);
-        sqlite3VdbeDeleteAuxData(pVdbeFunc, 0);
-        sqlite3DbFree(db, pVdbeFunc);
-        break;
-      }
-      case P4_FUNCDEF: {
-        freeEphemeralFunction(db, (FuncDef*)p4);
-        break;
-      }
-      case P4_MEM: {
-        sqlite3ValueFree((sqlite3_value*)p4);
-        break;
-      }
-      case P4_VTAB : {
-        sqlite3VtabUnlock((VTable *)p4);
-        break;
-      }
-      case P4_SUBPROGRAM : {
-        sqlite3VdbeProgramDelete(db, (SubProgram *)p4, 1);
-        break;
-      }
-    }
-  }
-}
-
-/*
-** Free the space allocated for aOp and any p4 values allocated for the
-** opcodes contained within. If aOp is not NULL it is assumed to contain 
-** nOp entries. 
-*/
-static void vdbeFreeOpArray(sqlite3 *db, Op *aOp, int nOp){
-  if( aOp ){
-    Op *pOp;
-    for(pOp=aOp; pOp<&aOp[nOp]; pOp++){
-      freeP4(db, pOp->p4type, pOp->p4.p);
-#ifdef SQLITE_DEBUG
-      sqlite3DbFree(db, pOp->zComment);
-#endif     
-    }
-  }
-  sqlite3DbFree(db, aOp);
-}
-
-/*
-** Decrement the ref-count on the SubProgram structure passed as the
-** second argument. If the ref-count reaches zero, free the structure.
-**
-** The array of VDBE opcodes stored as SubProgram.aOp is freed if
-** either the ref-count reaches zero or parameter freeop is non-zero.
-**
-** Since the array of opcodes pointed to by SubProgram.aOp may directly
-** or indirectly contain a reference to the SubProgram structure itself.
-** By passing a non-zero freeop parameter, the caller may ensure that all
-** SubProgram structures and their aOp arrays are freed, even when there
-** are such circular references.
-*/
-void sqlite3VdbeProgramDelete(sqlite3 *db, SubProgram *p, int freeop){
-  if( p ){
-    assert( p->nRef>0 );
-    if( freeop || p->nRef==1 ){
-      Op *aOp = p->aOp;
-      p->aOp = 0;
-      vdbeFreeOpArray(db, aOp, p->nOp);
-      p->nOp = 0;
-    }
-    p->nRef--;
-    if( p->nRef==0 ){
-      sqlite3DbFree(db, p);
-    }
-  }
-}
-
-
-/*
-** Change N opcodes starting at addr to No-ops.
-*/
-void sqlite3VdbeChangeToNoop(Vdbe *p, int addr, int N){
-  if( p->aOp ){
-    VdbeOp *pOp = &p->aOp[addr];
-    sqlite3 *db = p->db;
-    while( N-- ){
-      freeP4(db, pOp->p4type, pOp->p4.p);
-      memset(pOp, 0, sizeof(pOp[0]));
-      pOp->opcode = OP_Noop;
-      pOp++;
-    }
-  }
-}
-
-/*
-** Change the value of the P4 operand for a specific instruction.
-** This routine is useful when a large program is loaded from a
-** static array using sqlite3VdbeAddOpList but we want to make a
-** few minor changes to the program.
-**
-** If n>=0 then the P4 operand is dynamic, meaning that a copy of
-** the string is made into memory obtained from sqlite3_malloc().
-** A value of n==0 means copy bytes of zP4 up to and including the
-** first null byte.  If n>0 then copy n+1 bytes of zP4.
-**
-** If n==P4_KEYINFO it means that zP4 is a pointer to a KeyInfo structure.
-** A copy is made of the KeyInfo structure into memory obtained from
-** sqlite3_malloc, to be freed when the Vdbe is finalized.
-** n==P4_KEYINFO_HANDOFF indicates that zP4 points to a KeyInfo structure
-** stored in memory that the caller has obtained from sqlite3_malloc. The 
-** caller should not free the allocation, it will be freed when the Vdbe is
-** finalized.
-** 
-** Other values of n (P4_STATIC, P4_COLLSEQ etc.) indicate that zP4 points
-** to a string or structure that is guaranteed to exist for the lifetime of
-** the Vdbe. In these cases we can just copy the pointer.
-**
-** If addr<0 then change P4 on the most recently inserted instruction.
-*/
-void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
-  Op *pOp;
-  sqlite3 *db;
-  assert( p!=0 );
-  db = p->db;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  if( p->aOp==0 || db->mallocFailed ){
-    if ( n!=P4_KEYINFO && n!=P4_VTAB ) {
-      freeP4(db, n, (void*)*(char**)&zP4);
-    }
-    return;
-  }
-  assert( p->nOp>0 );
-  assert( addr<p->nOp );
-  if( addr<0 ){
-    addr = p->nOp - 1;
-  }
-  pOp = &p->aOp[addr];
-  freeP4(db, pOp->p4type, pOp->p4.p);
-  pOp->p4.p = 0;
-  if( n==P4_INT32 ){
-    /* Note: this cast is safe, because the origin data point was an int
-    ** that was cast to a (const char *). */
-    pOp->p4.i = SQLITE_PTR_TO_INT(zP4);
-    pOp->p4type = P4_INT32;
-  }else if( zP4==0 ){
-    pOp->p4.p = 0;
-    pOp->p4type = P4_NOTUSED;
-  }else if( n==P4_KEYINFO ){
-    KeyInfo *pKeyInfo;
-    int nField, nByte;
-
-    nField = ((KeyInfo*)zP4)->nField;
-    nByte = sizeof(*pKeyInfo) + (nField-1)*sizeof(pKeyInfo->aColl[0]) + nField;
-    pKeyInfo = sqlite3Malloc( nByte );
-    pOp->p4.pKeyInfo = pKeyInfo;
-    if( pKeyInfo ){
-      u8 *aSortOrder;
-      memcpy(pKeyInfo, zP4, nByte);
-      aSortOrder = pKeyInfo->aSortOrder;
-      if( aSortOrder ){
-        pKeyInfo->aSortOrder = (unsigned char*)&pKeyInfo->aColl[nField];
-        memcpy(pKeyInfo->aSortOrder, aSortOrder, nField);
-      }
-      pOp->p4type = P4_KEYINFO;
-    }else{
-      p->db->mallocFailed = 1;
-      pOp->p4type = P4_NOTUSED;
-    }
-  }else if( n==P4_KEYINFO_HANDOFF ){
-    pOp->p4.p = (void*)zP4;
-    pOp->p4type = P4_KEYINFO;
-  }else if( n==P4_VTAB ){
-    pOp->p4.p = (void*)zP4;
-    pOp->p4type = P4_VTAB;
-    sqlite3VtabLock((VTable *)zP4);
-    assert( ((VTable *)zP4)->db==p->db );
-  }else if( n<0 ){
-    pOp->p4.p = (void*)zP4;
-    pOp->p4type = (signed char)n;
-  }else{
-    if( n==0 ) n = sqlite3Strlen30(zP4);
-    pOp->p4.z = sqlite3DbStrNDup(p->db, zP4, n);
-    pOp->p4type = P4_DYNAMIC;
-  }
-}
-
-#ifndef NDEBUG
-/*
-** Change the comment on the the most recently coded instruction.  Or
-** insert a No-op and add the comment to that new instruction.  This
-** makes the code easier to read during debugging.  None of this happens
-** in a production build.
-*/
-void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
-  va_list ap;
-  if( !p ) return;
-  assert( p->nOp>0 || p->aOp==0 );
-  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
-  if( p->nOp ){
-    char **pz = &p->aOp[p->nOp-1].zComment;
-    va_start(ap, zFormat);
-    sqlite3DbFree(p->db, *pz);
-    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
-    va_end(ap);
-  }
-}
-void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
-  va_list ap;
-  if( !p ) return;
-  sqlite3VdbeAddOp0(p, OP_Noop);
-  assert( p->nOp>0 || p->aOp==0 );
-  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
-  if( p->nOp ){
-    char **pz = &p->aOp[p->nOp-1].zComment;
-    va_start(ap, zFormat);
-    sqlite3DbFree(p->db, *pz);
-    *pz = sqlite3VMPrintf(p->db, zFormat, ap);
-    va_end(ap);
-  }
-}
-#endif  /* NDEBUG */
-
-/*
-** Return the opcode for a given address.  If the address is -1, then
-** return the most recently inserted opcode.
-**
-** If a memory allocation error has occurred prior to the calling of this
-** routine, then a pointer to a dummy VdbeOp will be returned.  That opcode
-** is readable and writable, but it has no effect.  The return of a dummy
-** opcode allows the call to continue functioning after a OOM fault without
-** having to check to see if the return from this routine is a valid pointer.
-**
-** About the #ifdef SQLITE_OMIT_TRACE:  Normally, this routine is never called
-** unless p->nOp>0.  This is because in the absense of SQLITE_OMIT_TRACE,
-** an OP_Trace instruction is always inserted by sqlite3VdbeGet() as soon as
-** a new VDBE is created.  So we are free to set addr to p->nOp-1 without
-** having to double-check to make sure that the result is non-negative. But
-** if SQLITE_OMIT_TRACE is defined, the OP_Trace is omitted and we do need to
-** check the value of p->nOp-1 before continuing.
-*/
-VdbeOp *sqlite3VdbeGetOp(Vdbe *p, int addr){
-  static VdbeOp dummy;
-  assert( p->magic==VDBE_MAGIC_INIT );
-  if( addr<0 ){
-#ifdef SQLITE_OMIT_TRACE
-    if( p->nOp==0 ) return &dummy;
-#endif
-    addr = p->nOp - 1;
-  }
-  assert( (addr>=0 && addr<p->nOp) || p->db->mallocFailed );
-  if( p->db->mallocFailed ){
-    return &dummy;
-  }else{
-    return &p->aOp[addr];
-  }
-}
-
-#if !defined(SQLITE_OMIT_EXPLAIN) || !defined(NDEBUG) \
-     || defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
-/*
-** Compute a string that describes the P4 parameter for an opcode.
-** Use zTemp for any required temporary buffer space.
-*/
-static char *displayP4(Op *pOp, char *zTemp, int nTemp){
-  char *zP4 = zTemp;
-  assert( nTemp>=20 );
-  switch( pOp->p4type ){
-    case P4_KEYINFO_STATIC:
-    case P4_KEYINFO: {
-      int i, j;
-      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
-      sqlite3_snprintf(nTemp, zTemp, "keyinfo(%d", pKeyInfo->nField);
-      i = sqlite3Strlen30(zTemp);
-      for(j=0; j<pKeyInfo->nField; j++){
-        CollSeq *pColl = pKeyInfo->aColl[j];
-        if( pColl ){
-          int n = sqlite3Strlen30(pColl->zName);
-          if( i+n>nTemp-6 ){
-            memcpy(&zTemp[i],",...",4);
-            break;
-          }
-          zTemp[i++] = ',';
-          if( pKeyInfo->aSortOrder && pKeyInfo->aSortOrder[j] ){
-            zTemp[i++] = '-';
-          }
-          memcpy(&zTemp[i], pColl->zName,n+1);
-          i += n;
-        }else if( i+4<nTemp-6 ){
-          memcpy(&zTemp[i],",nil",4);
-          i += 4;
-        }
-      }
-      zTemp[i++] = ')';
-      zTemp[i] = 0;
-      assert( i<nTemp );
-      break;
-    }
-    case P4_COLLSEQ: {
-      CollSeq *pColl = pOp->p4.pColl;
-      sqlite3_snprintf(nTemp, zTemp, "collseq(%.20s)", pColl->zName);
-      break;
-    }
-    case P4_FUNCDEF: {
-      FuncDef *pDef = pOp->p4.pFunc;
-      sqlite3_snprintf(nTemp, zTemp, "%s(%d)", pDef->zName, pDef->nArg);
-      break;
-    }
-    case P4_INT64: {
-      sqlite3_snprintf(nTemp, zTemp, "%lld", *pOp->p4.pI64);
-      break;
-    }
-    case P4_INT32: {
-      sqlite3_snprintf(nTemp, zTemp, "%d", pOp->p4.i);
-      break;
-    }
-    case P4_REAL: {
-      sqlite3_snprintf(nTemp, zTemp, "%.16g", *pOp->p4.pReal);
-      break;
-    }
-    case P4_MEM: {
-      Mem *pMem = pOp->p4.pMem;
-      assert( (pMem->flags & MEM_Null)==0 );
-      if( pMem->flags & MEM_Str ){
-        zP4 = pMem->z;
-      }else if( pMem->flags & MEM_Int ){
-        sqlite3_snprintf(nTemp, zTemp, "%lld", pMem->u.i);
-      }else if( pMem->flags & MEM_Real ){
-        sqlite3_snprintf(nTemp, zTemp, "%.16g", pMem->r);
-      }else{
-        assert( pMem->flags & MEM_Blob );
-        zP4 = "(blob)";
-      }
-      break;
-    }
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    case P4_VTAB: {
-      sqlite3_vtab *pVtab = pOp->p4.pVtab->pVtab;
-      sqlite3_snprintf(nTemp, zTemp, "vtab:%p:%p", pVtab, pVtab->pModule);
-      break;
-    }
-#endif
-    case P4_INTARRAY: {
-      sqlite3_snprintf(nTemp, zTemp, "intarray");
-      break;
-    }
-    case P4_SUBPROGRAM: {
-      sqlite3_snprintf(nTemp, zTemp, "program");
-      break;
-    }
-    default: {
-      zP4 = pOp->p4.z;
-      if( zP4==0 ){
-        zP4 = zTemp;
-        zTemp[0] = 0;
-      }
-    }
-  }
-  assert( zP4!=0 );
-  return zP4;
-}
-#endif
-
-/*
-** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
-*/
-void sqlite3VdbeUsesBtree(Vdbe *p, int i){
-  int mask;
-  assert( i>=0 && i<p->db->nDb && i<sizeof(u32)*8 );
-  assert( i<(int)sizeof(p->btreeMask)*8 );
-  mask = ((u32)1)<<i;
-  if( (p->btreeMask & mask)==0 ){
-    p->btreeMask |= mask;
-    sqlite3BtreeMutexArrayInsert(&p->aMutex, p->db->aDb[i].pBt);
-  }
-}
-
-
-#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
-/*
-** Print a single opcode.  This routine is used for debugging only.
-*/
-void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
-  char *zP4;
-  char zPtr[50];
-  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-4s %.2X %s\n";
-  if( pOut==0 ) pOut = stdout;
-  zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
-  fprintf(pOut, zFormat1, pc, 
-      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
-#ifdef SQLITE_DEBUG
-      pOp->zComment ? pOp->zComment : ""
-#else
-      ""
-#endif
-  );
-  fflush(pOut);
-}
-#endif
-
-/*
-** Release an array of N Mem elements
-*/
-static void releaseMemArray(Mem *p, int N){
-  if( p && N ){
-    Mem *pEnd;
-    sqlite3 *db = p->db;
-    u8 malloc_failed = db->mallocFailed;
-    for(pEnd=&p[N]; p<pEnd; p++){
-      assert( (&p[1])==pEnd || p[0].db==p[1].db );
-
-      /* This block is really an inlined version of sqlite3VdbeMemRelease()
-      ** that takes advantage of the fact that the memory cell value is 
-      ** being set to NULL after releasing any dynamic resources.
-      **
-      ** The justification for duplicating code is that according to 
-      ** callgrind, this causes a certain test case to hit the CPU 4.7 
-      ** percent less (x86 linux, gcc version 4.1.2, -O6) than if 
-      ** sqlite3MemRelease() were called from here. With -O2, this jumps
-      ** to 6.6 percent. The test case is inserting 1000 rows into a table 
-      ** with no indexes using a single prepared INSERT statement, bind() 
-      ** and reset(). Inserts are grouped into a transaction.
-      */
-      if( p->flags&(MEM_Agg|MEM_Dyn|MEM_Frame|MEM_RowSet) ){
-        sqlite3VdbeMemRelease(p);
-      }else if( p->zMalloc ){
-        sqlite3DbFree(db, p->zMalloc);
-        p->zMalloc = 0;
-      }
-
-      p->flags = MEM_Null;
-    }
-    db->mallocFailed = malloc_failed;
-  }
-}
-
-/*
-** Delete a VdbeFrame object and its contents. VdbeFrame objects are
-** allocated by the OP_Program opcode in sqlite3VdbeExec().
-*/
-void sqlite3VdbeFrameDelete(VdbeFrame *p){
-  int i;
-  Mem *aMem = VdbeFrameMem(p);
-  VdbeCursor **apCsr = (VdbeCursor **)&aMem[p->nChildMem];
-  for(i=0; i<p->nChildCsr; i++){
-    sqlite3VdbeFreeCursor(p->v, apCsr[i]);
-  }
-  releaseMemArray(aMem, p->nChildMem);
-  sqlite3DbFree(p->v->db, p);
-}
-
-
-#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
-int sqlite3VdbeReleaseBuffers(Vdbe *p){
-  int ii;
-  int nFree = 0;
-  assert( sqlite3_mutex_held(p->db->mutex) );
-  for(ii=1; ii<=p->nMem; ii++){
-    Mem *pMem = &p->aMem[ii];
-    if( pMem->flags & MEM_RowSet ){
-      sqlite3RowSetClear(pMem->u.pRowSet);
-    }
-    if( pMem->z && pMem->flags&MEM_Dyn ){
-      assert( !pMem->xDel );
-      nFree += sqlite3DbMallocSize(pMem->db, pMem->z);
-      sqlite3VdbeMemRelease(pMem);
-    }
-  }
-  return nFree;
-}
-#endif
-
-#ifndef SQLITE_OMIT_EXPLAIN
-/*
-** Give a listing of the program in the virtual machine.
-**
-** The interface is the same as sqlite3VdbeExec().  But instead of
-** running the code, it invokes the callback once for each instruction.
-** This feature is used to implement "EXPLAIN".
-**
-** When p->explain==1, each instruction is listed.  When
-** p->explain==2, only OP_Explain instructions are listed and these
-** are shown in a different format.  p->explain==2 is used to implement
-** EXPLAIN QUERY PLAN.
-*/
-int sqlite3VdbeList(
-  Vdbe *p                   /* The VDBE */
-){
-  int nRow;                            /* Total number of rows to return */
-  int nSub = 0;                        /* Number of sub-vdbes seen so far */
-  SubProgram **apSub = 0;              /* Array of sub-vdbes */
-  Mem *pSub = 0;
-  sqlite3 *db = p->db;
-  int i;
-  int rc = SQLITE_OK;
-  Mem *pMem = p->pResultSet = &p->aMem[1];
-
-  assert( p->explain );
-  assert( p->magic==VDBE_MAGIC_RUN );
-  assert( db->magic==SQLITE_MAGIC_BUSY );
-  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );
-
-  /* Even though this opcode does not use dynamic strings for
-  ** the result, result columns may become dynamic if the user calls
-  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
-  */
-  releaseMemArray(pMem, 8);
-
-  if( p->rc==SQLITE_NOMEM ){
-    /* This happens if a malloc() inside a call to sqlite3_column_text() or
-    ** sqlite3_column_text16() failed.  */
-    db->mallocFailed = 1;
-    return SQLITE_ERROR;
-  }
-
-  /* Figure out total number of rows that will be returned by this 
-  ** EXPLAIN program.  */
-  nRow = p->nOp;
-  if( p->explain==1 ){
-    pSub = &p->aMem[9];
-    if( pSub->flags&MEM_Blob ){
-      nSub = pSub->n/sizeof(Vdbe*);
-      apSub = (SubProgram **)pSub->z;
-    }
-    for(i=0; i<nSub; i++){
-      nRow += apSub[i]->nOp;
-    }
-  }
-
-  do{
-    i = p->pc++;
-  }while( i<nRow && p->explain==2 && p->aOp[i].opcode!=OP_Explain );
-  if( i>=nRow ){
-    p->rc = SQLITE_OK;
-    rc = SQLITE_DONE;
-  }else if( db->u1.isInterrupted ){
-    p->rc = SQLITE_INTERRUPT;
-    rc = SQLITE_ERROR;
-    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3ErrStr(p->rc));
-  }else{
-    char *z;
-    Op *pOp;
-    if( i<p->nOp ){
-      pOp = &p->aOp[i];
-    }else{
-      int j;
-      i -= p->nOp;
-      for(j=0; i>=apSub[j]->nOp; j++){
-        i -= apSub[j]->nOp;
-      }
-      pOp = &apSub[j]->aOp[i];
-    }
-    if( p->explain==1 ){
-      pMem->flags = MEM_Int;
-      pMem->type = SQLITE_INTEGER;
-      pMem->u.i = i;                                /* Program counter */
-      pMem++;
-  
-      pMem->flags = MEM_Static|MEM_Str|MEM_Term;
-      pMem->z = (char*)sqlite3OpcodeName(pOp->opcode);  /* Opcode */
-      assert( pMem->z!=0 );
-      pMem->n = sqlite3Strlen30(pMem->z);
-      pMem->type = SQLITE_TEXT;
-      pMem->enc = SQLITE_UTF8;
-      pMem++;
-
-      if( pOp->p4type==P4_SUBPROGRAM ){
-        int nByte = (nSub+1)*sizeof(SubProgram*);
-        int j;
-        for(j=0; j<nSub; j++){
-          if( apSub[j]==pOp->p4.pProgram ) break;
-        }
-        if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, 1) ){
-          apSub = (SubProgram **)pSub->z;
-          apSub[nSub++] = pOp->p4.pProgram;
-          pSub->flags |= MEM_Blob;
-          pSub->n = nSub*sizeof(SubProgram*);
-        }
-      }
-    }
-
-    pMem->flags = MEM_Int;
-    pMem->u.i = pOp->p1;                          /* P1 */
-    pMem->type = SQLITE_INTEGER;
-    pMem++;
-
-    pMem->flags = MEM_Int;
-    pMem->u.i = pOp->p2;                          /* P2 */
-    pMem->type = SQLITE_INTEGER;
-    pMem++;
-
-    if( p->explain==1 ){
-      pMem->flags = MEM_Int;
-      pMem->u.i = pOp->p3;                          /* P3 */
-      pMem->type = SQLITE_INTEGER;
-      pMem++;
-    }
-
-    if( sqlite3VdbeMemGrow(pMem, 32, 0) ){            /* P4 */
-      assert( p->db->mallocFailed );
-      return SQLITE_ERROR;
-    }
-    pMem->flags = MEM_Dyn|MEM_Str|MEM_Term;
-    z = displayP4(pOp, pMem->z, 32);
-    if( z!=pMem->z ){
-      sqlite3VdbeMemSetStr(pMem, z, -1, SQLITE_UTF8, 0);
-    }else{
-      assert( pMem->z!=0 );
-      pMem->n = sqlite3Strlen30(pMem->z);
-      pMem->enc = SQLITE_UTF8;
-    }
-    pMem->type = SQLITE_TEXT;
-    pMem++;
-
-    if( p->explain==1 ){
-      if( sqlite3VdbeMemGrow(pMem, 4, 0) ){
-        assert( p->db->mallocFailed );
-        return SQLITE_ERROR;
-      }
-      pMem->flags = MEM_Dyn|MEM_Str|MEM_Term;
-      pMem->n = 2;
-      sqlite3_snprintf(3, pMem->z, "%.2x", pOp->p5);   /* P5 */
-      pMem->type = SQLITE_TEXT;
-      pMem->enc = SQLITE_UTF8;
-      pMem++;
-  
-#ifdef SQLITE_DEBUG
-      if( pOp->zComment ){
-        pMem->flags = MEM_Str|MEM_Term;
-        pMem->z = pOp->zComment;
-        pMem->n = sqlite3Strlen30(pMem->z);
-        pMem->enc = SQLITE_UTF8;
-        pMem->type = SQLITE_TEXT;
-      }else
-#endif
-      {
-        pMem->flags = MEM_Null;                       /* Comment */
-        pMem->type = SQLITE_NULL;
-      }
-    }
-
-    p->nResColumn = 8 - 5*(p->explain-1);
-    p->rc = SQLITE_OK;
-    rc = SQLITE_ROW;
-  }
-  return rc;
-}
-#endif /* SQLITE_OMIT_EXPLAIN */
-
-#ifdef SQLITE_DEBUG
-/*
-** Print the SQL that was used to generate a VDBE program.
-*/
-void sqlite3VdbePrintSql(Vdbe *p){
-  int nOp = p->nOp;
-  VdbeOp *pOp;
-  if( nOp<1 ) return;
-  pOp = &p->aOp[0];
-  if( pOp->opcode==OP_Trace && pOp->p4.z!=0 ){
-    const char *z = pOp->p4.z;
-    while( sqlite3Isspace(*z) ) z++;
-    printf("SQL: [%s]\n", z);
-  }
-}
-#endif
-
-#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
-/*
-** Print an IOTRACE message showing SQL content.
-*/
-void sqlite3VdbeIOTraceSql(Vdbe *p){
-  int nOp = p->nOp;
-  VdbeOp *pOp;
-  if( sqlite3IoTrace==0 ) return;
-  if( nOp<1 ) return;
-  pOp = &p->aOp[0];
-  if( pOp->opcode==OP_Trace && pOp->p4.z!=0 ){
-    int i, j;
-    char z[1000];
-    sqlite3_snprintf(sizeof(z), z, "%s", pOp->p4.z);
-    for(i=0; sqlite3Isspace(z[i]); i++){}
-    for(j=0; z[i]; i++){
-      if( sqlite3Isspace(z[i]) ){
-        if( z[i-1]!=' ' ){
-          z[j++] = ' ';
-        }
-      }else{
-        z[j++] = z[i];
-      }
-    }
-    z[j] = 0;
-    sqlite3IoTrace("SQL %s\n", z);
-  }
-}
-#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */
-
-/*
-** Allocate space from a fixed size buffer.  Make *pp point to the
-** allocated space.  (Note:  pp is a char* rather than a void** to
-** work around the pointer aliasing rules of C.)  *pp should initially
-** be zero.  If *pp is not zero, that means that the space has already
-** been allocated and this routine is a noop.
-**
-** nByte is the number of bytes of space needed.
-**
-** *ppFrom point to available space and pEnd points to the end of the
-** available space.
-**
-** *pnByte is a counter of the number of bytes of space that have failed
-** to allocate.  If there is insufficient space in *ppFrom to satisfy the
-** request, then increment *pnByte by the amount of the request.
-*/
-static void allocSpace(
-  char *pp,            /* IN/OUT: Set *pp to point to allocated buffer */
-  int nByte,           /* Number of bytes to allocate */
-  u8 **ppFrom,         /* IN/OUT: Allocate from *ppFrom */
-  u8 *pEnd,            /* Pointer to 1 byte past the end of *ppFrom buffer */
-  int *pnByte          /* If allocation cannot be made, increment *pnByte */
-){
-  assert( EIGHT_BYTE_ALIGNMENT(*ppFrom) );
-  if( (*(void**)pp)==0 ){
-    nByte = ROUND8(nByte);
-    if( &(*ppFrom)[nByte] <= pEnd ){
-      *(void**)pp = (void *)*ppFrom;
-      *ppFrom += nByte;
-    }else{
-      *pnByte += nByte;
-    }
-  }
-}
-
-/*
-** Prepare a virtual machine for execution.  This involves things such
-** as allocating stack space and initializing the program counter.
-** After the VDBE has be prepped, it can be executed by one or more
-** calls to sqlite3VdbeExec().  
-**
-** This is the only way to move a VDBE from VDBE_MAGIC_INIT to
-** VDBE_MAGIC_RUN.
-**
-** This function may be called more than once on a single virtual machine.
-** The first call is made while compiling the SQL statement. Subsequent
-** calls are made as part of the process of resetting a statement to be
-** re-executed (from a call to sqlite3_reset()). The nVar, nMem, nCursor 
-** and isExplain parameters are only passed correct values the first time
-** the function is called. On subsequent calls, from sqlite3_reset(), nVar
-** is passed -1 and nMem, nCursor and isExplain are all passed zero.
-*/
-void sqlite3VdbeMakeReady(
-  Vdbe *p,                       /* The VDBE */
-  int nVar,                      /* Number of '?' see in the SQL statement */
-  int nMem,                      /* Number of memory cells to allocate */
-  int nCursor,                   /* Number of cursors to allocate */
-  int nArg,                      /* Maximum number of args in SubPrograms */
-  int isExplain,                 /* True if the EXPLAIN keywords is present */
-  int usesStmtJournal            /* True to set Vdbe.usesStmtJournal */
-){
-  int n;
-  sqlite3 *db = p->db;
-
-  assert( p!=0 );
-  assert( p->magic==VDBE_MAGIC_INIT );
-
-  /* There should be at least one opcode.
-  */
-  assert( p->nOp>0 );
-
-  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
-  p->magic = VDBE_MAGIC_RUN;
-
-  /* For each cursor required, also allocate a memory cell. Memory
-  ** cells (nMem+1-nCursor)..nMem, inclusive, will never be used by
-  ** the vdbe program. Instead they are used to allocate space for
-  ** VdbeCursor/BtCursor structures. The blob of memory associated with 
-  ** cursor 0 is stored in memory cell nMem. Memory cell (nMem-1)
-  ** stores the blob of memory associated with cursor 1, etc.
-  **
-  ** See also: allocateCursor().
-  */
-  nMem += nCursor;
-
-  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
-  ** an array to marshal SQL function arguments in. This is only done the
-  ** first time this function is called for a given VDBE, not when it is
-  ** being called from sqlite3_reset() to reset the virtual machine.
-  */
-  if( nVar>=0 && ALWAYS(db->mallocFailed==0) ){
-    u8 *zCsr = (u8 *)&p->aOp[p->nOp];
-    u8 *zEnd = (u8 *)&p->aOp[p->nOpAlloc];
-    int nByte;
-    resolveP2Values(p, &nArg);
-    p->usesStmtJournal = (u8)usesStmtJournal;
-    if( isExplain && nMem<10 ){
-      nMem = 10;
-    }
-    memset(zCsr, 0, zEnd-zCsr);
-    zCsr += (zCsr - (u8*)0)&7;
-    assert( EIGHT_BYTE_ALIGNMENT(zCsr) );
-
-    do {
-      nByte = 0;
-      allocSpace((char*)&p->aMem, nMem*sizeof(Mem), &zCsr, zEnd, &nByte);
-      allocSpace((char*)&p->aVar, nVar*sizeof(Mem), &zCsr, zEnd, &nByte);
-      allocSpace((char*)&p->apArg, nArg*sizeof(Mem*), &zCsr, zEnd, &nByte);
-      allocSpace((char*)&p->azVar, nVar*sizeof(char*), &zCsr, zEnd, &nByte);
-      allocSpace((char*)&p->apCsr, 
-                 nCursor*sizeof(VdbeCursor*), &zCsr, zEnd, &nByte
-      );
-      if( nByte ){
-        p->pFree = sqlite3DbMallocZero(db, nByte);
-      }
-      zCsr = p->pFree;
-      zEnd = &zCsr[nByte];
-    }while( nByte && !db->mallocFailed );
-
-    p->nCursor = (u16)nCursor;
-    if( p->aVar ){
-      p->nVar = (u16)nVar;
-      for(n=0; n<nVar; n++){
-        p->aVar[n].flags = MEM_Null;
-        p->aVar[n].db = db;
-      }
-    }
-    if( p->aMem ){
-      p->aMem--;                      /* aMem[] goes from 1..nMem */
-      p->nMem = nMem;                 /*       not from 0..nMem-1 */
-      for(n=1; n<=nMem; n++){
-        p->aMem[n].flags = MEM_Null;
-        p->aMem[n].db = db;
-      }
-    }
-  }
-#ifdef SQLITE_DEBUG
-  for(n=1; n<p->nMem; n++){
-    assert( p->aMem[n].db==db );
-  }
-#endif
-
-  p->pc = -1;
-  p->rc = SQLITE_OK;
-  p->errorAction = OE_Abort;
-  p->explain |= isExplain;
-  p->magic = VDBE_MAGIC_RUN;
-  p->nChange = 0;
-  p->cacheCtr = 1;
-  p->minWriteFileFormat = 255;
-  p->iStatement = 0;
-#ifdef VDBE_PROFILE
-  {
-    int i;
-    for(i=0; i<p->nOp; i++){
-      p->aOp[i].cnt = 0;
-      p->aOp[i].cycles = 0;
-    }
-  }
-#endif
-}
-
-/*
-** Close a VDBE cursor and release all the resources that cursor 
-** happens to hold.
-*/
-void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
-  if( pCx==0 ){
-    return;
-  }
-  if( pCx->pBt ){
-    sqlite3BtreeClose(pCx->pBt);
-    /* The pCx->pCursor will be close automatically, if it exists, by
-    ** the call above. */
-  }else if( pCx->pCursor ){
-    sqlite3BtreeCloseCursor(pCx->pCursor);
-  }
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-  if( pCx->pVtabCursor ){
-    sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
-    const sqlite3_module *pModule = pCx->pModule;
-    p->inVtabMethod = 1;
-    (void)sqlite3SafetyOff(p->db);
-    pModule->xClose(pVtabCursor);
-    (void)sqlite3SafetyOn(p->db);
-    p->inVtabMethod = 0;
-  }
-#endif
-}
-
-/*
-** Copy the values stored in the VdbeFrame structure to its Vdbe. This
-** is used, for example, when a trigger sub-program is halted to restore
-** control to the main program.
-*/
-int sqlite3VdbeFrameRestore(VdbeFrame *pFrame){
-  Vdbe *v = pFrame->v;
-  v->aOp = pFrame->aOp;
-  v->nOp = pFrame->nOp;
-  v->aMem = pFrame->aMem;
-  v->nMem = pFrame->nMem;
-  v->apCsr = pFrame->apCsr;
-  v->nCursor = pFrame->nCursor;
-  v->db->lastRowid = pFrame->lastRowid;
-  v->nChange = pFrame->nChange;
-  return pFrame->pc;
-}
-
-/*
-** Close all cursors.
-**
-** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
-** cell array. This is necessary as the memory cell array may contain
-** pointers to VdbeFrame objects, which may in turn contain pointers to
-** open cursors.
-*/
-static void closeAllCursors(Vdbe *p){
-  if( p->pFrame ){
-    VdbeFrame *pFrame = p->pFrame;
-    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
-    sqlite3VdbeFrameRestore(pFrame);
-  }
-  p->pFrame = 0;
-  p->nFrame = 0;
-
-  if( p->apCsr ){
-    int i;
-    for(i=0; i<p->nCursor; i++){
-      VdbeCursor *pC = p->apCsr[i];
-      if( pC ){
-        sqlite3VdbeFreeCursor(p, pC);
-        p->apCsr[i] = 0;
-      }
-    }
-  }
-  if( p->aMem ){
-    releaseMemArray(&p->aMem[1], p->nMem);
-  }
-}
-
-/*
-** Clean up the VM after execution.
-**
-** This routine will automatically close any cursors, lists, and/or
-** sorters that were left open.  It also deletes the values of
-** variables in the aVar[] array.
-*/
-static void Cleanup(Vdbe *p){
-  sqlite3 *db = p->db;
-
-#ifdef SQLITE_DEBUG
-  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
-  ** Vdbe.aMem[] arrays have already been cleaned up.  */
-  int i;
-  for(i=0; i<p->nCursor; i++) assert( p->apCsr==0 || p->apCsr[i]==0 );
-  for(i=1; i<=p->nMem; i++) assert( p->aMem==0 || p->aMem[i].flags==MEM_Null );
-#endif
-
-  sqlite3DbFree(db, p->zErrMsg);
-  p->zErrMsg = 0;
-  p->pResultSet = 0;
-}
-
-/*
-** Set the number of result columns that will be returned by this SQL
-** statement. This is now set at compile time, rather than during
-** execution of the vdbe program so that sqlite3_column_count() can
-** be called on an SQL statement before sqlite3_step().
-*/
-void sqlite3VdbeSetNumCols(Vdbe *p, int nResColumn){
-  Mem *pColName;
-  int n;
-  sqlite3 *db = p->db;
-
-  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
-  sqlite3DbFree(db, p->aColName);
-  n = nResColumn*COLNAME_N;
-  p->nResColumn = (u16)nResColumn;
-  p->aColName = pColName = (Mem*)sqlite3DbMallocZero(db, sizeof(Mem)*n );
-  if( p->aColName==0 ) return;
-  while( n-- > 0 ){
-    pColName->flags = MEM_Null;
-    pColName->db = p->db;
-    pColName++;
-  }
-}
-
-/*
-** Set the name of the idx'th column to be returned by the SQL statement.
-** zName must be a pointer to a nul terminated string.
-**
-** This call must be made after a call to sqlite3VdbeSetNumCols().
-**
-** The final parameter, xDel, must be one of SQLITE_DYNAMIC, SQLITE_STATIC
-** or SQLITE_TRANSIENT. If it is SQLITE_DYNAMIC, then the buffer pointed
-** to by zName will be freed by sqlite3DbFree() when the vdbe is destroyed.
-*/
-int sqlite3VdbeSetColName(
-  Vdbe *p,                         /* Vdbe being configured */
-  int idx,                         /* Index of column zName applies to */
-  int var,                         /* One of the COLNAME_* constants */
-  const char *zName,               /* Pointer to buffer containing name */
-  void (*xDel)(void*)              /* Memory management strategy for zName */
-){
-  int rc;
-  Mem *pColName;
-  assert( idx<p->nResColumn );
-  assert( var<COLNAME_N );
-  if( p->db->mallocFailed ){
-    assert( !zName || xDel!=SQLITE_DYNAMIC );
-    return SQLITE_NOMEM;
-  }
-  assert( p->aColName!=0 );
-  pColName = &(p->aColName[idx+var*p->nResColumn]);
-  rc = sqlite3VdbeMemSetStr(pColName, zName, -1, SQLITE_UTF8, xDel);
-  assert( rc!=0 || !zName || (pColName->flags&MEM_Term)!=0 );
-  return rc;
-}
-
-/*
-** A read or write transaction may or may not be active on database handle
-** db. If a transaction is active, commit it. If there is a
-** write-transaction spanning more than one database file, this routine
-** takes care of the master journal trickery.
-*/
-static int vdbeCommit(sqlite3 *db, Vdbe *p){
-  int i;
-  int nTrans = 0;  /* Number of databases with an active write-transaction */
-  int rc = SQLITE_OK;
-  int needXcommit = 0;
-
-#ifdef SQLITE_OMIT_VIRTUALTABLE
-  /* With this option, sqlite3VtabSync() is defined to be simply 
-  ** SQLITE_OK so p is not used. 
-  */
-  UNUSED_PARAMETER(p);
-#endif
-
-  /* Before doing anything else, call the xSync() callback for any
-  ** virtual module tables written in this transaction. This has to
-  ** be done before determining whether a master journal file is 
-  ** required, as an xSync() callback may add an attached database
-  ** to the transaction.
-  */
-  rc = sqlite3VtabSync(db, &p->zErrMsg);
-  if( rc!=SQLITE_OK ){
-    return rc;
-  }
-
-  /* This loop determines (a) if the commit hook should be invoked and
-  ** (b) how many database files have open write transactions, not 
-  ** including the temp database. (b) is important because if more than 
-  ** one database file has an open write transaction, a master journal
-  ** file is required for an atomic commit.
-  */ 
-  for(i=0; i<db->nDb; i++){ 
-    Btree *pBt = db->aDb[i].pBt;
-    if( sqlite3BtreeIsInTrans(pBt) ){
-      needXcommit = 1;
-      if( i!=1 ) nTrans++;
-    }
-  }
-
-  /* If there are any write-transactions at all, invoke the commit hook */
-  if( needXcommit && db->xCommitCallback ){
-    (void)sqlite3SafetyOff(db);
-    rc = db->xCommitCallback(db->pCommitArg);
-    (void)sqlite3SafetyOn(db);
-    if( rc ){
-      return SQLITE_CONSTRAINT;
-    }
-  }
-
-  /* The simple case - no more than one database file (not counting the
-  ** TEMP database) has a transaction active.   There is no need for the
-  ** master-journal.
-  **
-  ** If the return value of sqlite3BtreeGetFilename() is a zero length
-  ** string, it means the main database is :memory: or a temp file.  In 
-  ** that case we do not support atomic multi-file commits, so use the 
-  ** simple case then too.
-  */
-  if( 0==sqlite3Strlen30(sqlite3BtreeGetFilename(db->aDb[0].pBt))
-   || nTrans<=1
-  ){
-    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        rc = sqlite3BtreeCommitPhaseOne(pBt, 0);
-      }
-    }
-
-    /* Do the commit only if all databases successfully complete phase 1. 
-    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
-    ** IO error while deleting or truncating a journal file. It is unlikely,
-    ** but could happen. In this case abandon processing and return the error.
-    */
-    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        rc = sqlite3BtreeCommitPhaseTwo(pBt);
-      }
-    }
-    if( rc==SQLITE_OK ){
-      sqlite3VtabCommit(db);
-    }
-  }
-
-  /* The complex case - There is a multi-file write-transaction active.
-  ** This requires a master journal file to ensure the transaction is
-  ** committed atomicly.
-  */
-#ifndef SQLITE_OMIT_DISKIO
-  else{
-    sqlite3_vfs *pVfs = db->pVfs;
-    int needSync = 0;
-    char *zMaster = 0;   /* File-name for the master journal */
-    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
-    sqlite3_file *pMaster = 0;
-    i64 offset = 0;
-    int res;
-
-    /* Select a master journal file name */
-    do {
-      u32 iRandom;
-      sqlite3DbFree(db, zMaster);
-      sqlite3_randomness(sizeof(iRandom), &iRandom);
-      zMaster = sqlite3MPrintf(db, "%s-mj%08X", zMainFile, iRandom&0x7fffffff);
-      if( !zMaster ){
-        return SQLITE_NOMEM;
-      }
-      rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
-    }while( rc==SQLITE_OK && res );
-    if( rc==SQLITE_OK ){
-      /* Open the master journal. */
-      rc = sqlite3OsOpenMalloc(pVfs, zMaster, &pMaster, 
-          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
-          SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_MASTER_JOURNAL, 0
-      );
-    }
-    if( rc!=SQLITE_OK ){
-      sqlite3DbFree(db, zMaster);
-      return rc;
-    }
- 
-    /* Write the name of each database file in the transaction into the new
-    ** master journal file. If an error occurs at this point close
-    ** and delete the master journal file. All the individual journal files
-    ** still have 'null' as the master journal pointer, so they will roll
-    ** back independently if a failure occurs.
-    */
-    for(i=0; i<db->nDb; i++){
-      Btree *pBt = db->aDb[i].pBt;
-      if( i==1 ) continue;   /* Ignore the TEMP database */
-      if( sqlite3BtreeIsInTrans(pBt) ){
-        char const *zFile = sqlite3BtreeGetJournalname(pBt);
-        if( zFile[0]==0 ) continue;  /* Ignore :memory: databases */
-        if( !needSync && !sqlite3BtreeSyncDisabled(pBt) ){
-          needSync = 1;
-        }
-        rc = sqlite3OsWrite(pMaster, zFile, sqlite3Strlen30(zFile)+1, offset);
-        offset += sqlite3Strlen30(zFile)+1;
-        if( rc!=SQLITE_OK ){
-          sqlite3OsCloseFree(pMaster);
-          sqlite3OsDelete(pVfs, zMaster, 0);
-          sqlite3DbFree(db, zMaster);
-          return rc;
-        }
-      }
-    }
-
-    /* Sync the master journal file. If the IOCAP_SEQUENTIAL device
-    ** flag is set this is not required.
-    */
-    if( needSync 
-     && 0==(sqlite3OsDeviceCharacteristics(pMaster)&SQLITE_IOCAP_SEQUENTIAL)
-     && SQLITE_OK!=(rc = sqlite3OsSync(pMaster, SQLITE_SYNC_NORMAL))
-    ){
-      sqlite3OsCloseFree(pMaster);
-      sqlite3OsDelete(pVfs, zMaster, 0);
-      sqlite3DbFree(db, zMaster);
-      return rc;
-    }
-
-    /* Sync all the db files involved in the transaction. The same call
-    ** sets the master journal pointer in each individual journal. If
-    ** an error occurs here, do not delete the master journal file.
-    **
-    ** If the error occurs during the first call to
-    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the
-    ** master journal file will be orphaned. But we cannot delete it,
-    ** in case the master journal file name was written into the journal
-    ** file before the failure occurred.
-    */
-    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
-      }
-    }
-    sqlite3OsCloseFree(pMaster);
-    if( rc!=SQLITE_OK ){
-      sqlite3DbFree(db, zMaster);
-      return rc;
-    }
-
-    /* Delete the master journal file. This commits the transaction. After
-    ** doing this the directory is synced again before any individual
-    ** transaction files are deleted.
-    */
-    rc = sqlite3OsDelete(pVfs, zMaster, 1);
-    sqlite3DbFree(db, zMaster);
-    zMaster = 0;
-    if( rc ){
-      return rc;
-    }
-
-    /* All files and directories have already been synced, so the following
-    ** calls to sqlite3BtreeCommitPhaseTwo() are only closing files and
-    ** deleting or truncating journals. If something goes wrong while
-    ** this is happening we don't really care. The integrity of the
-    ** transaction is already guaranteed, but some stray 'cold' journals
-    ** may be lying around. Returning an error code won't help matters.
-    */
-    disable_simulated_io_errors();
-    sqlite3BeginBenignMalloc();
-    for(i=0; i<db->nDb; i++){ 
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        sqlite3BtreeCommitPhaseTwo(pBt);
-      }
-    }
-    sqlite3EndBenignMalloc();
-    enable_simulated_io_errors();
-
-    sqlite3VtabCommit(db);
-  }
-#endif
-
-  return rc;
-}
-
-/* 
-** This routine checks that the sqlite3.activeVdbeCnt count variable
-** matches the number of vdbe's in the list sqlite3.pVdbe that are
-** currently active. An assertion fails if the two counts do not match.
-** This is an internal self-check only - it is not an essential processing
-** step.
-**
-** This is a no-op if NDEBUG is defined.
-*/
-#ifndef NDEBUG
-static void checkActiveVdbeCnt(sqlite3 *db){
-  Vdbe *p;
-  int cnt = 0;
-  int nWrite = 0;
-  p = db->pVdbe;
-  while( p ){
-    if( p->magic==VDBE_MAGIC_RUN && p->pc>=0 ){
-      cnt++;
-      if( p->readOnly==0 ) nWrite++;
-    }
-    p = p->pNext;
-  }
-  assert( cnt==db->activeVdbeCnt );
-  assert( nWrite==db->writeVdbeCnt );
-}
-#else
-#define checkActiveVdbeCnt(x)
-#endif
-
-/*
-** For every Btree that in database connection db which 
-** has been modified, "trip" or invalidate each cursor in
-** that Btree might have been modified so that the cursor
-** can never be used again.  This happens when a rollback
-*** occurs.  We have to trip all the other cursors, even
-** cursor from other VMs in different database connections,
-** so that none of them try to use the data at which they
-** were pointing and which now may have been changed due
-** to the rollback.
-**
-** Remember that a rollback can delete tables complete and
-** reorder rootpages.  So it is not sufficient just to save
-** the state of the cursor.  We have to invalidate the cursor
-** so that it is never used again.
-*/
-static void invalidateCursorsOnModifiedBtrees(sqlite3 *db){
-  int i;
-  for(i=0; i<db->nDb; i++){
-    Btree *p = db->aDb[i].pBt;
-    if( p && sqlite3BtreeIsInTrans(p) ){
-      sqlite3BtreeTripAllCursors(p, SQLITE_ABORT);
-    }
-  }
-}
-
-/*
-** If the Vdbe passed as the first argument opened a statement-transaction,
-** close it now. Argument eOp must be either SAVEPOINT_ROLLBACK or
-** SAVEPOINT_RELEASE. If it is SAVEPOINT_ROLLBACK, then the statement
-** transaction is rolled back. If eOp is SAVEPOINT_RELEASE, then the 
-** statement transaction is commtted.
-**
-** If an IO error occurs, an SQLITE_IOERR_XXX error code is returned. 
-** Otherwise SQLITE_OK.
-*/
-int sqlite3VdbeCloseStatement(Vdbe *p, int eOp){
-  sqlite3 *const db = p->db;
-  int rc = SQLITE_OK;
-
-  /* If p->iStatement is greater than zero, then this Vdbe opened a 
-  ** statement transaction that should be closed here. The only exception
-  ** is that an IO error may have occured, causing an emergency rollback.
-  ** In this case (db->nStatement==0), and there is nothing to do.
-  */
-  if( db->nStatement && p->iStatement ){
-    int i;
-    const int iSavepoint = p->iStatement-1;
-
-    assert( eOp==SAVEPOINT_ROLLBACK || eOp==SAVEPOINT_RELEASE);
-    assert( db->nStatement>0 );
-    assert( p->iStatement==(db->nStatement+db->nSavepoint) );
-
-    for(i=0; i<db->nDb; i++){ 
-      int rc2 = SQLITE_OK;
-      Btree *pBt = db->aDb[i].pBt;
-      if( pBt ){
-        if( eOp==SAVEPOINT_ROLLBACK ){
-          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_ROLLBACK, iSavepoint);
-        }
-        if( rc2==SQLITE_OK ){
-          rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_RELEASE, iSavepoint);
-        }
-        if( rc==SQLITE_OK ){
-          rc = rc2;
-        }
-      }
-    }
-    db->nStatement--;
-    p->iStatement = 0;
-  }
-  return rc;
-}
-
-/*
-** If SQLite is compiled to support shared-cache mode and to be threadsafe,
-** this routine obtains the mutex associated with each BtShared structure
-** that may be accessed by the VM passed as an argument. In doing so it
-** sets the BtShared.db member of each of the BtShared structures, ensuring
-** that the correct busy-handler callback is invoked if required.
-**
-** If SQLite is not threadsafe but does support shared-cache mode, then
-** sqlite3BtreeEnterAll() is invoked to set the BtShared.db variables
-** of all of BtShared structures accessible via the database handle 
-** associated with the VM. Of course only a subset of these structures
-** will be accessed by the VM, and we could use Vdbe.btreeMask to figure
-** that subset out, but there is no advantage to doing so.
-**
-** If SQLite is not threadsafe and does not support shared-cache mode, this
-** function is a no-op.
-*/
-#ifndef SQLITE_OMIT_SHARED_CACHE
-void sqlite3VdbeMutexArrayEnter(Vdbe *p){
-#if SQLITE_THREADSAFE
-  sqlite3BtreeMutexArrayEnter(&p->aMutex);
-#else
-  sqlite3BtreeEnterAll(p->db);
-#endif
-}
-#endif
-
-/*
-** This routine is called the when a VDBE tries to halt.  If the VDBE
-** has made changes and is in autocommit mode, then commit those
-** changes.  If a rollback is needed, then do the rollback.
-**
-** This routine is the only way to move the state of a VM from
-** SQLITE_MAGIC_RUN to SQLITE_MAGIC_HALT.  It is harmless to
-** call this on a VM that is in the SQLITE_MAGIC_HALT state.
-**
-** Return an error code.  If the commit could not complete because of
-** lock contention, return SQLITE_BUSY.  If SQLITE_BUSY is returned, it
-** means the close did not happen and needs to be repeated.
-*/
-int sqlite3VdbeHalt(Vdbe *p){
-  int rc;                         /* Used to store transient return codes */
-  sqlite3 *db = p->db;
-
-  /* This function contains the logic that determines if a statement or
-  ** transaction will be committed or rolled back as a result of the
-  ** execution of this virtual machine. 
-  **
-  ** If any of the following errors occur:
-  **
-  **     SQLITE_NOMEM
-  **     SQLITE_IOERR
-  **     SQLITE_FULL
-  **     SQLITE_INTERRUPT
-  **
-  ** Then the internal cache might have been left in an inconsistent
-  ** state.  We need to rollback the statement transaction, if there is
-  ** one, or the complete transaction if there is no statement transaction.
-  */
-
-  if( p->db->mallocFailed ){
-    p->rc = SQLITE_NOMEM;
-  }
-  closeAllCursors(p);
-  if( p->magic!=VDBE_MAGIC_RUN ){
-    return SQLITE_OK;
-  }
-  checkActiveVdbeCnt(db);
-
-  /* No commit or rollback needed if the program never started */
-  if( p->pc>=0 ){
-    int mrc;   /* Primary error code from p->rc */
-    int eStatementOp = 0;
-    int isSpecialError;            /* Set to true if a 'special' error */
-
-    /* Lock all btrees used by the statement */
-    sqlite3VdbeMutexArrayEnter(p);
-
-    /* Check for one of the special errors */
-    mrc = p->rc & 0xff;
-    assert( p->rc!=SQLITE_IOERR_BLOCKED );  /* This error no longer exists */
-    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
-                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
-    if( isSpecialError ){
-      /* If the query was read-only, we need do no rollback at all. Otherwise,
-      ** proceed with the special handling.
-      */
-      if( !p->readOnly || mrc!=SQLITE_INTERRUPT ){
-        if( (mrc==SQLITE_NOMEM || mrc==SQLITE_FULL) && p->usesStmtJournal ){
-          eStatementOp = SAVEPOINT_ROLLBACK;
-        }else{
-          /* We are forced to roll back the active transaction. Before doing
-          ** so, abort any other statements this handle currently has active.
-          */
-          invalidateCursorsOnModifiedBtrees(db);
-          sqlite3RollbackAll(db);
-          sqlite3CloseSavepoints(db);
-          db->autoCommit = 1;
-        }
-      }
-    }
-  
-    /* If the auto-commit flag is set and this is the only active writer 
-    ** VM, then we do either a commit or rollback of the current transaction. 
-    **
-    ** Note: This block also runs if one of the special errors handled 
-    ** above has occurred. 
-    */
-    if( !sqlite3VtabInSync(db) 
-     && db->autoCommit 
-     && db->writeVdbeCnt==(p->readOnly==0) 
-    ){
-      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
-        /* The auto-commit flag is true, and the vdbe program was 
-        ** successful or hit an 'OR FAIL' constraint. This means a commit 
-        ** is required.
-        */
-        rc = vdbeCommit(db, p);
-        if( rc==SQLITE_BUSY ){
-          sqlite3BtreeMutexArrayLeave(&p->aMutex);
-          return SQLITE_BUSY;
-        }else if( rc!=SQLITE_OK ){
-          p->rc = rc;
-          sqlite3RollbackAll(db);
-        }else{
-          sqlite3CommitInternalChanges(db);
-        }
-      }else{
-        sqlite3RollbackAll(db);
-      }
-      db->nStatement = 0;
-    }else if( eStatementOp==0 ){
-      if( p->rc==SQLITE_OK || p->errorAction==OE_Fail ){
-        eStatementOp = SAVEPOINT_RELEASE;
-      }else if( p->errorAction==OE_Abort ){
-        eStatementOp = SAVEPOINT_ROLLBACK;
-      }else{
-        invalidateCursorsOnModifiedBtrees(db);
-        sqlite3RollbackAll(db);
-        sqlite3CloseSavepoints(db);
-        db->autoCommit = 1;
-      }
-    }
-  
-    /* If eStatementOp is non-zero, then a statement transaction needs to
-    ** be committed or rolled back. Call sqlite3VdbeCloseStatement() to
-    ** do so. If this operation returns an error, and the current statement
-    ** error code is SQLITE_OK or SQLITE_CONSTRAINT, then set the error
-    ** code to the new value.
-    */
-    if( eStatementOp ){
-      rc = sqlite3VdbeCloseStatement(p, eStatementOp);
-      if( rc && (p->rc==SQLITE_OK || p->rc==SQLITE_CONSTRAINT) ){
-        p->rc = rc;
-        sqlite3DbFree(db, p->zErrMsg);
-        p->zErrMsg = 0;
-      }
-    }
-  
-    /* If this was an INSERT, UPDATE or DELETE and no statement transaction
-    ** has been rolled back, update the database connection change-counter. 
-    */
-    if( p->changeCntOn ){
-      if( eStatementOp!=SAVEPOINT_ROLLBACK ){
-        sqlite3VdbeSetChanges(db, p->nChange);
-      }else{
-        sqlite3VdbeSetChanges(db, 0);
-      }
-      p->nChange = 0;
-    }
-  
-    /* Rollback or commit any schema changes that occurred. */
-    if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
-      sqlite3ResetInternalSchema(db, 0);
-      db->flags = (db->flags | SQLITE_InternChanges);
-    }
-
-    /* Release the locks */
-    sqlite3BtreeMutexArrayLeave(&p->aMutex);
-  }
-
-  /* We have successfully halted and closed the VM.  Record this fact. */
-  if( p->pc>=0 ){
-    db->activeVdbeCnt--;
-    if( !p->readOnly ){
-      db->writeVdbeCnt--;
-    }
-    assert( db->activeVdbeCnt>=db->writeVdbeCnt );
-  }
-  p->magic = VDBE_MAGIC_HALT;
-  checkActiveVdbeCnt(db);
-  if( p->db->mallocFailed ){
-    p->rc = SQLITE_NOMEM;
-  }
-
-  /* If the auto-commit flag is set to true, then any locks that were held
-  ** by connection db have now been released. Call sqlite3ConnectionUnlocked() 
-  ** to invoke any required unlock-notify callbacks.
-  */
-  if( db->autoCommit ){
-    sqlite3ConnectionUnlocked(db);
-  }
-
-  assert( db->activeVdbeCnt>0 || db->autoCommit==0 || db->nStatement==0 );
-  return SQLITE_OK;
-}
-
-
-/*
-** Each VDBE holds the result of the most recent sqlite3_step() call
-** in p->rc.  This routine sets that result back to SQLITE_OK.
-*/
-void sqlite3VdbeResetStepResult(Vdbe *p){
-  p->rc = SQLITE_OK;
-}
-
-/*
-** Clean up a VDBE after execution but do not delete the VDBE just yet.
-** Write any error messages into *pzErrMsg.  Return the result code.
-**
-** After this routine is run, the VDBE should be ready to be executed
-** again.
-**
-** To look at it another way, this routine resets the state of the
-** virtual machine from VDBE_MAGIC_RUN or VDBE_MAGIC_HALT back to
-** VDBE_MAGIC_INIT.
-*/
-int sqlite3VdbeReset(Vdbe *p){
-  sqlite3 *db;
-  db = p->db;
-
-  /* If the VM did not run to completion or if it encountered an
-  ** error, then it might not have been halted properly.  So halt
-  ** it now.
-  */
-  (void)sqlite3SafetyOn(db);
-  sqlite3VdbeHalt(p);
-  (void)sqlite3SafetyOff(db);
-
-  /* If the VDBE has be run even partially, then transfer the error code
-  ** and error message from the VDBE into the main database structure.  But
-  ** if the VDBE has just been set to run but has not actually executed any
-  ** instructions yet, leave the main database error information unchanged.
-  */
-  if( p->pc>=0 ){
-    if( p->zErrMsg ){
-      sqlite3BeginBenignMalloc();
-      sqlite3ValueSetStr(db->pErr,-1,p->zErrMsg,SQLITE_UTF8,SQLITE_TRANSIENT);
-      sqlite3EndBenignMalloc();
-      db->errCode = p->rc;
-      sqlite3DbFree(db, p->zErrMsg);
-      p->zErrMsg = 0;
-    }else if( p->rc ){
-      sqlite3Error(db, p->rc, 0);
-    }else{
-      sqlite3Error(db, SQLITE_OK, 0);
-    }
-  }else if( p->rc && p->expired ){
-    /* The expired flag was set on the VDBE before the first call
-    ** to sqlite3_step(). For consistency (since sqlite3_step() was
-    ** called), set the database error in this case as well.
-    */
-    sqlite3Error(db, p->rc, 0);
-    sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
-    sqlite3DbFree(db, p->zErrMsg);
-    p->zErrMsg = 0;
-  }
-
-  /* Reclaim all memory used by the VDBE
-  */
-  Cleanup(p);
-
-  /* Save profiling information from this VDBE run.
-  */
-#ifdef VDBE_PROFILE
-  {
-    FILE *out = fopen("vdbe_profile.out", "a");
-    if( out ){
-      int i;
-      fprintf(out, "---- ");
-      for(i=0; i<p->nOp; i++){
-        fprintf(out, "%02x", p->aOp[i].opcode);
-      }
-      fprintf(out, "\n");
-      for(i=0; i<p->nOp; i++){
-        fprintf(out, "%6d %10lld %8lld ",
-           p->aOp[i].cnt,
-           p->aOp[i].cycles,
-           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
-        );
-        sqlite3VdbePrintOp(out, i, &p->aOp[i]);
-      }
-      fclose(out);
-    }
-  }
-#endif
-  p->magic = VDBE_MAGIC_INIT;
-  return p->rc & db->errMask;
-}
- 
-/*
-** Clean up and delete a VDBE after execution.  Return an integer which is
-** the result code.  Write any error message text into *pzErrMsg.
-*/
-int sqlite3VdbeFinalize(Vdbe *p){
-  int rc = SQLITE_OK;
-  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
-    rc = sqlite3VdbeReset(p);
-    assert( (rc & p->db->errMask)==rc );
-  }
-  sqlite3VdbeDelete(p);
-  return rc;
-}
-
-/*
-** Call the destructor for each auxdata entry in pVdbeFunc for which
-** the corresponding bit in mask is clear.  Auxdata entries beyond 31
-** are always destroyed.  To destroy all auxdata entries, call this
-** routine with mask==0.
-*/
-void sqlite3VdbeDeleteAuxData(VdbeFunc *pVdbeFunc, int mask){
-  int i;
-  for(i=0; i<pVdbeFunc->nAux; i++){
-    struct AuxData *pAux = &pVdbeFunc->apAux[i];
-    if( (i>31 || !(mask&(((u32)1)<<i))) && pAux->pAux ){
-      if( pAux->xDelete ){
-        pAux->xDelete(pAux->pAux);
-      }
-      pAux->pAux = 0;
-    }
-  }
-}
-
-/*
-** Delete an entire VDBE.
-*/
-void sqlite3VdbeDelete(Vdbe *p){
-  sqlite3 *db;
-
-  if( NEVER(p==0) ) return;
-  db = p->db;
-  if( p->pPrev ){
-    p->pPrev->pNext = p->pNext;
-  }else{
-    assert( db->pVdbe==p );
-    db->pVdbe = p->pNext;
-  }
-  if( p->pNext ){
-    p->pNext->pPrev = p->pPrev;
-  }
-  releaseMemArray(p->aVar, p->nVar);
-  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
-  vdbeFreeOpArray(db, p->aOp, p->nOp);
-  sqlite3DbFree(db, p->aLabel);
-  sqlite3DbFree(db, p->aColName);
-  sqlite3DbFree(db, p->zSql);
-  p->magic = VDBE_MAGIC_DEAD;
-  sqlite3DbFree(db, p->pFree);
-  sqlite3DbFree(db, p);
-}
-
-/*
-** Make sure the cursor p is ready to read or write the row to which it
-** was last positioned.  Return an error code if an OOM fault or I/O error
-** prevents us from positioning the cursor to its correct position.
-**
-** If a MoveTo operation is pending on the given cursor, then do that
-** MoveTo now.  If no move is pending, check to see if the row has been
-** deleted out from under the cursor and if it has, mark the row as
-** a NULL row.
-**
-** If the cursor is already pointing to the correct row and that row has
-** not been deleted out from under the cursor, then this routine is a no-op.
-*/
-int sqlite3VdbeCursorMoveto(VdbeCursor *p){
-  if( p->deferredMoveto ){
-    int res, rc;
-#ifdef SQLITE_TEST
-    extern int sqlite3_search_count;
-#endif
-    assert( p->isTable );
-    rc = sqlite3BtreeMovetoUnpacked(p->pCursor, 0, p->movetoTarget, 0, &res);
-    if( rc ) return rc;
-    p->lastRowid = p->movetoTarget;
-    p->rowidIsValid = ALWAYS(res==0) ?1:0;
-    if( NEVER(res<0) ){
-      rc = sqlite3BtreeNext(p->pCursor, &res);
-      if( rc ) return rc;
-    }
-#ifdef SQLITE_TEST
-    sqlite3_search_count++;
-#endif
-    p->deferredMoveto = 0;
-    p->cacheStatus = CACHE_STALE;
-  }else if( ALWAYS(p->pCursor) ){
-    int hasMoved;
-    int rc = sqlite3BtreeCursorHasMoved(p->pCursor, &hasMoved);
-    if( rc ) return rc;
-    if( hasMoved ){
-      p->cacheStatus = CACHE_STALE;
-      p->nullRow = 1;
-    }
-  }
-  return SQLITE_OK;
-}
-
-/*
-** The following functions:
-**
-** sqlite3VdbeSerialType()
-** sqlite3VdbeSerialTypeLen()
-** sqlite3VdbeSerialLen()
-** sqlite3VdbeSerialPut()
-** sqlite3VdbeSerialGet()
-**
-** encapsulate the code that serializes values for storage in SQLite
-** data and index records. Each serialized value consists of a
-** 'serial-type' and a blob of data. The serial type is an 8-byte unsigned
-** integer, stored as a varint.
-**
-** In an SQLite index record, the serial type is stored directly before
-** the blob of data that it corresponds to. In a table record, all serial
-** types are stored at the start of the record, and the blobs of data at
-** the end. Hence these functions allow the caller to handle the
-** serial-type and data blob seperately.
-**
-** The following table describes the various storage classes for data:
-**
-**   serial type        bytes of data      type
-**   --------------     ---------------    ---------------
-**      0                     0            NULL
-**      1                     1            signed integer
-**      2                     2            signed integer
-**      3                     3            signed integer
-**      4                     4            signed integer
-**      5                     6            signed integer
-**      6                     8            signed integer
-**      7                     8            IEEE float
-**      8                     0            Integer constant 0
-**      9                     0            Integer constant 1
-**     10,11                               reserved for expansion
-**    N>=12 and even       (N-12)/2        BLOB
-**    N>=13 and odd        (N-13)/2        text
-**
-** The 8 and 9 types were added in 3.3.0, file format 4.  Prior versions
-** of SQLite will not understand those serial types.
-*/
-
-/*
-** Return the serial-type for the value stored in pMem.
-*/
-u32 sqlite3VdbeSerialType(Mem *pMem, int file_format){
-  int flags = pMem->flags;
-  int n;
-
-  if( flags&MEM_Null ){
-    return 0;
-  }
-  if( flags&MEM_Int ){
-    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
-#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
-    i64 i = pMem->u.i;
-    u64 u;
-    if( file_format>=4 && (i&1)==i ){
-      return 8+(u32)i;
-    }
-    u = i<0 ? -i : i;
-    if( u<=127 ) return 1;
-    if( u<=32767 ) return 2;
-    if( u<=8388607 ) return 3;
-    if( u<=2147483647 ) return 4;
-    if( u<=MAX_6BYTE ) return 5;
-    return 6;
-  }
-  if( flags&MEM_Real ){
-    return 7;
-  }
-  assert( pMem->db->mallocFailed || flags&(MEM_Str|MEM_Blob) );
-  n = pMem->n;
-  if( flags & MEM_Zero ){
-    n += pMem->u.nZero;
-  }
-  assert( n>=0 );
-  return ((n*2) + 12 + ((flags&MEM_Str)!=0));
-}
-
-/*
-** Return the length of the data corresponding to the supplied serial-type.
-*/
-u32 sqlite3VdbeSerialTypeLen(u32 serial_type){
-  if( serial_type>=12 ){
-    return (serial_type-12)/2;
-  }else{
-    static const u8 aSize[] = { 0, 1, 2, 3, 4, 6, 8, 8, 0, 0, 0, 0 };
-    return aSize[serial_type];
-  }
-}
-
-/*
-** If we are on an architecture with mixed-endian floating 
-** points (ex: ARM7) then swap the lower 4 bytes with the 
-** upper 4 bytes.  Return the result.
-**
-** For most architectures, this is a no-op.
-**
-** (later):  It is reported to me that the mixed-endian problem
-** on ARM7 is an issue with GCC, not with the ARM7 chip.  It seems
-** that early versions of GCC stored the two words of a 64-bit
-** float in the wrong order.  And that error has been propagated
-** ever since.  The blame is not necessarily with GCC, though.
-** GCC might have just copying the problem from a prior compiler.
-** I am also told that newer versions of GCC that follow a different
-** ABI get the byte order right.
-**
-** Developers using SQLite on an ARM7 should compile and run their
-** application using -DSQLITE_DEBUG=1 at least once.  With DEBUG
-** enabled, some asserts below will ensure that the byte order of
-** floating point values is correct.
-**
-** (2007-08-30)  Frank van Vugt has studied this problem closely
-** and has send his findings to the SQLite developers.  Frank
-** writes that some Linux kernels offer floating point hardware
-** emulation that uses only 32-bit mantissas instead of a full 
-** 48-bits as required by the IEEE standard.  (This is the
-** CONFIG_FPE_FASTFPE option.)  On such systems, floating point
-** byte swapping becomes very complicated.  To avoid problems,
-** the necessary byte swapping is carried out using a 64-bit integer
-** rather than a 64-bit float.  Frank assures us that the code here
-** works for him.  We, the developers, have no way to independently
-** verify this, but Frank seems to know what he is talking about
-** so we trust him.
-*/
-#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
-static u64 floatSwap(u64 in){
-  union {
-    u64 r;
-    u32 i[2];
-  } u;
-  u32 t;
-
-  u.r = in;
-  t = u.i[0];
-  u.i[0] = u.i[1];
-  u.i[1] = t;
-  return u.r;
-}
-# define swapMixedEndianFloat(X)  X = floatSwap(X)
-#else
-# define swapMixedEndianFloat(X)
-#endif
-
-/*
-** Write the serialized data blob for the value stored in pMem into 
-** buf. It is assumed that the caller has allocated sufficient space.
-** Return the number of bytes written.
-**
-** nBuf is the amount of space left in buf[].  nBuf must always be
-** large enough to hold the entire field.  Except, if the field is
-** a blob with a zero-filled tail, then buf[] might be just the right
-** size to hold everything except for the zero-filled tail.  If buf[]
-** is only big enough to hold the non-zero prefix, then only write that
-** prefix into buf[].  But if buf[] is large enough to hold both the
-** prefix and the tail then write the prefix and set the tail to all
-** zeros.
-**
-** Return the number of bytes actually written into buf[].  The number
-** of bytes in the zero-filled tail is included in the return value only
-** if those bytes were zeroed in buf[].
-*/ 
-u32 sqlite3VdbeSerialPut(u8 *buf, int nBuf, Mem *pMem, int file_format){
-  u32 serial_type = sqlite3VdbeSerialType(pMem, file_format);
-  u32 len;
-
-  /* Integer and Real */
-  if( serial_type<=7 && serial_type>0 ){
-    u64 v;
-    u32 i;
-    if( serial_type==7 ){
-      assert( sizeof(v)==sizeof(pMem->r) );
-      memcpy(&v, &pMem->r, sizeof(v));
-      swapMixedEndianFloat(v);
-    }else{
-      v = pMem->u.i;
-    }
-    len = i = sqlite3VdbeSerialTypeLen(serial_type);
-    assert( len<=(u32)nBuf );
-    while( i-- ){
-      buf[i] = (u8)(v&0xFF);
-      v >>= 8;
-    }
-    return len;
-  }
-
-  /* String or blob */
-  if( serial_type>=12 ){
-    assert( pMem->n + ((pMem->flags & MEM_Zero)?pMem->u.nZero:0)
-             == (int)sqlite3VdbeSerialTypeLen(serial_type) );
-    assert( pMem->n<=nBuf );
-    len = pMem->n;
-    memcpy(buf, pMem->z, len);
-    if( pMem->flags & MEM_Zero ){
-      len += pMem->u.nZero;
-      assert( nBuf>=0 );
-      if( len > (u32)nBuf ){
-        len = (u32)nBuf;
-      }
-      memset(&buf[pMem->n], 0, len-pMem->n);
-    }
-    return len;
-  }
-
-  /* NULL or constants 0 or 1 */
-  return 0;
-}
-
-/*
-** Deserialize the data blob pointed to by buf as serial type serial_type
-** and store the result in pMem.  Return the number of bytes read.
-*/ 
-u32 sqlite3VdbeSerialGet(
-  const unsigned char *buf,     /* Buffer to deserialize from */
-  u32 serial_type,              /* Serial type to deserialize */
-  Mem *pMem                     /* Memory cell to write value into */
-){
-  switch( serial_type ){
-    case 10:   /* Reserved for future use */
-    case 11:   /* Reserved for future use */
-    case 0: {  /* NULL */
-      pMem->flags = MEM_Null;
-      break;
-    }
-    case 1: { /* 1-byte signed integer */
-      pMem->u.i = (signed char)buf[0];
-      pMem->flags = MEM_Int;
-      return 1;
-    }
-    case 2: { /* 2-byte signed integer */
-      pMem->u.i = (((signed char)buf[0])<<8) | buf[1];
-      pMem->flags = MEM_Int;
-      return 2;
-    }
-    case 3: { /* 3-byte signed integer */
-      pMem->u.i = (((signed char)buf[0])<<16) | (buf[1]<<8) | buf[2];
-      pMem->flags = MEM_Int;
-      return 3;
-    }
-    case 4: { /* 4-byte signed integer */
-      pMem->u.i = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
-      pMem->flags = MEM_Int;
-      return 4;
-    }
-    case 5: { /* 6-byte signed integer */
-      u64 x = (((signed char)buf[0])<<8) | buf[1];
-      u32 y = (buf[2]<<24) | (buf[3]<<16) | (buf[4]<<8) | buf[5];
-      x = (x<<32) | y;
-      pMem->u.i = *(i64*)&x;
-      pMem->flags = MEM_Int;
-      return 6;
-    }
-    case 6:   /* 8-byte signed integer */
-    case 7: { /* IEEE floating point */
-      u64 x;
-      u32 y;
-#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
-      /* Verify that integers and floating point values use the same
-      ** byte order.  Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
-      ** defined that 64-bit floating point values really are mixed
-      ** endian.
-      */
-      static const u64 t1 = ((u64)0x3ff00000)<<32;
-      static const double r1 = 1.0;
-      u64 t2 = t1;
-      swapMixedEndianFloat(t2);
-      assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
-#endif
-
-      x = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
-      y = (buf[4]<<24) | (buf[5]<<16) | (buf[6]<<8) | buf[7];
-      x = (x<<32) | y;
-      if( serial_type==6 ){
-        pMem->u.i = *(i64*)&x;
-        pMem->flags = MEM_Int;
-      }else{
-        assert( sizeof(x)==8 && sizeof(pMem->r)==8 );
-        swapMixedEndianFloat(x);
-        memcpy(&pMem->r, &x, sizeof(x));
-        pMem->flags = sqlite3IsNaN(pMem->r) ? MEM_Null : MEM_Real;
-      }
-      return 8;
-    }
-    case 8:    /* Integer 0 */
-    case 9: {  /* Integer 1 */
-      pMem->u.i = serial_type-8;
-      pMem->flags = MEM_Int;
-      return 0;
-    }
-    default: {
-      u32 len = (serial_type-12)/2;
-      pMem->z = (char *)buf;
-      pMem->n = len;
-      pMem->xDel = 0;
-      if( serial_type&0x01 ){
-        pMem->flags = MEM_Str | MEM_Ephem;
-      }else{
-        pMem->flags = MEM_Blob | MEM_Ephem;
-      }
-      return len;
-    }
-  }
-  return 0;
-}
-
-
-/*
-** Given the nKey-byte encoding of a record in pKey[], parse the
-** record into a UnpackedRecord structure.  Return a pointer to
-** that structure.
-**
-** The calling function might provide szSpace bytes of memory
-** space at pSpace.  This space can be used to hold the returned
-** VDbeParsedRecord structure if it is large enough.  If it is
-** not big enough, space is obtained from sqlite3_malloc().
-**
-** The returned structure should be closed by a call to
-** sqlite3VdbeDeleteUnpackedRecord().
-*/ 
-UnpackedRecord *sqlite3VdbeRecordUnpack(
-  KeyInfo *pKeyInfo,     /* Information about the record format */
-  int nKey,              /* Size of the binary record */
-  const void *pKey,      /* The binary record */
-  char *pSpace,          /* Unaligned space available to hold the object */
-  int szSpace            /* Size of pSpace[] in bytes */
-){
-  const unsigned char *aKey = (const unsigned char *)pKey;
-  UnpackedRecord *p;  /* The unpacked record that we will return */
-  int nByte;          /* Memory space needed to hold p, in bytes */
-  int d;
-  u32 idx;
-  u16 u;              /* Unsigned loop counter */
-  u32 szHdr;
-  Mem *pMem;
-  int nOff;           /* Increase pSpace by this much to 8-byte align it */
-  
-  /*
-  ** We want to shift the pointer pSpace up such that it is 8-byte aligned.
-  ** Thus, we need to calculate a value, nOff, between 0 and 7, to shift 
-  ** it by.  If pSpace is already 8-byte aligned, nOff should be zero.
-  */
-  nOff = (8 - (SQLITE_PTR_TO_INT(pSpace) & 7)) & 7;
-  pSpace += nOff;
-  szSpace -= nOff;
-  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nField+1);
-  if( nByte>szSpace ){
-    p = sqlite3DbMallocRaw(pKeyInfo->db, nByte);
-    if( p==0 ) return 0;
-    p->flags = UNPACKED_NEED_FREE | UNPACKED_NEED_DESTROY;
-  }else{
-    p = (UnpackedRecord*)pSpace;
-    p->flags = UNPACKED_NEED_DESTROY;
-  }
-  p->pKeyInfo = pKeyInfo;
-  p->nField = pKeyInfo->nField + 1;
-  p->aMem = pMem = (Mem*)&((char*)p)[ROUND8(sizeof(UnpackedRecord))];
-  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
-  idx = getVarint32(aKey, szHdr);
-  d = szHdr;
-  u = 0;
-  while( idx<szHdr && u<p->nField && d<=nKey ){
-    u32 serial_type;
-
-    idx += getVarint32(&aKey[idx], serial_type);
-    pMem->enc = pKeyInfo->enc;
-    pMem->db = pKeyInfo->db;
-    pMem->flags = 0;
-    pMem->zMalloc = 0;
-    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
-    pMem++;
-    u++;
-  }
-  assert( u<=pKeyInfo->nField + 1 );
-  p->nField = u;
-  return (void*)p;
-}
-
-/*
-** This routine destroys a UnpackedRecord object.
-*/
-void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord *p){
-  int i;
-  Mem *pMem;
-
-  assert( p!=0 );
-  assert( p->flags & UNPACKED_NEED_DESTROY );
-  for(i=0, pMem=p->aMem; i<p->nField; i++, pMem++){
-    /* The unpacked record is always constructed by the
-    ** sqlite3VdbeUnpackRecord() function above, which makes all
-    ** strings and blobs static.  And none of the elements are
-    ** ever transformed, so there is never anything to delete.
-    */
-    if( NEVER(pMem->zMalloc) ) sqlite3VdbeMemRelease(pMem);
-  }
-  if( p->flags & UNPACKED_NEED_FREE ){
-    sqlite3DbFree(p->pKeyInfo->db, p);
-  }
-}
-
-/*
-** This function compares the two table rows or index records
-** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
-** or positive integer if key1 is less than, equal to or 
-** greater than key2.  The {nKey1, pKey1} key must be a blob
-** created by th OP_MakeRecord opcode of the VDBE.  The pPKey2
-** key must be a parsed key such as obtained from
-** sqlite3VdbeParseRecord.
-**
-** Key1 and Key2 do not have to contain the same number of fields.
-** The key with fewer fields is usually compares less than the 
-** longer key.  However if the UNPACKED_INCRKEY flags in pPKey2 is set
-** and the common prefixes are equal, then key1 is less than key2.
-** Or if the UNPACKED_MATCH_PREFIX flag is set and the prefixes are
-** equal, then the keys are considered to be equal and
-** the parts beyond the common prefix are ignored.
-**
-** If the UNPACKED_IGNORE_ROWID flag is set, then the last byte of
-** the header of pKey1 is ignored.  It is assumed that pKey1 is
-** an index key, and thus ends with a rowid value.  The last byte
-** of the header will therefore be the serial type of the rowid:
-** one of 1, 2, 3, 4, 5, 6, 8, or 9 - the integer serial types.
-** The serial type of the final rowid will always be a single byte.
-** By ignoring this last byte of the header, we force the comparison
-** to ignore the rowid at the end of key1.
-*/
-int sqlite3VdbeRecordCompare(
-  int nKey1, const void *pKey1, /* Left key */
-  UnpackedRecord *pPKey2        /* Right key */
-){
-  int d1;            /* Offset into aKey[] of next data element */
-  u32 idx1;          /* Offset into aKey[] of next header element */
-  u32 szHdr1;        /* Number of bytes in header */
-  int i = 0;
-  int nField;
-  int rc = 0;
-  const unsigned char *aKey1 = (const unsigned char *)pKey1;
-  KeyInfo *pKeyInfo;
-  Mem mem1;
-
-  pKeyInfo = pPKey2->pKeyInfo;
-  mem1.enc = pKeyInfo->enc;
-  mem1.db = pKeyInfo->db;
-  mem1.flags = 0;
-  mem1.u.i = 0;  /* not needed, here to silence compiler warning */
-  mem1.zMalloc = 0;
-  
-  idx1 = getVarint32(aKey1, szHdr1);
-  d1 = szHdr1;
-  if( pPKey2->flags & UNPACKED_IGNORE_ROWID ){
-    szHdr1--;
-  }
-  nField = pKeyInfo->nField;
-  while( idx1<szHdr1 && i<pPKey2->nField ){
-    u32 serial_type1;
-
-    /* Read the serial types for the next element in each key. */
-    idx1 += getVarint32( aKey1+idx1, serial_type1 );
-    if( d1>=nKey1 && sqlite3VdbeSerialTypeLen(serial_type1)>0 ) break;
-
-    /* Extract the values to be compared.
-    */
-    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
-
-    /* Do the comparison
-    */
-    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i],
-                           i<nField ? pKeyInfo->aColl[i] : 0);
-    if( rc!=0 ){
-      break;
-    }
-    i++;
-  }
-
-  /* No memory allocation is ever used on mem1. */
-  if( NEVER(mem1.zMalloc) ) sqlite3VdbeMemRelease(&mem1);
-
-  /* If the PREFIX_SEARCH flag is set and all fields except the final
-  ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
-  ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
-  ** This is used by the OP_IsUnique opcode.
-  */
-  if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
-    assert( idx1==szHdr1 && rc );
-    assert( mem1.flags & MEM_Int );
-    pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
-    pPKey2->rowid = mem1.u.i;
-  }
-
-  if( rc==0 ){
-    /* rc==0 here means that one of the keys ran out of fields and
-    ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
-    ** flag is set, then break the tie by treating key2 as larger.
-    ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
-    ** are considered to be equal.  Otherwise, the longer key is the 
-    ** larger.  As it happens, the pPKey2 will always be the longer
-    ** if there is a difference.
-    */
-    if( pPKey2->flags & UNPACKED_INCRKEY ){
-      rc = -1;
-    }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
-      /* Leave rc==0 */
-    }else if( idx1<szHdr1 ){
-      rc = 1;
-    }
-  }else if( pKeyInfo->aSortOrder && i<pKeyInfo->nField
-               && pKeyInfo->aSortOrder[i] ){
-    rc = -rc;
-  }
-
-  return rc;
-}
- 
-
-/*
-** pCur points at an index entry created using the OP_MakeRecord opcode.
-** Read the rowid (the last field in the record) and store it in *rowid.
-** Return SQLITE_OK if everything works, or an error code otherwise.
-**
-** pCur might be pointing to text obtained from a corrupt database file.
-** So the content cannot be trusted.  Do appropriate checks on the content.
-*/
-int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
-  i64 nCellKey = 0;
-  int rc;
-  u32 szHdr;        /* Size of the header */
-  u32 typeRowid;    /* Serial type of the rowid */
-  u32 lenRowid;     /* Size of the rowid */
-  Mem m, v;
-
-  UNUSED_PARAMETER(db);
-
-  /* Get the size of the index entry.  Only indices entries of less
-  ** than 2GiB are support - anything large must be database corruption.
-  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
-  ** this code can safely assume that nCellKey is 32-bits  
-  */
-  assert( sqlite3BtreeCursorIsValid(pCur) );
-  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
-  assert( rc==SQLITE_OK );     /* pCur is always valid so KeySize cannot fail */
-  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
-
-  /* Read in the complete content of the index entry */
-  memset(&m, 0, sizeof(m));
-  rc = sqlite3VdbeMemFromBtree(pCur, 0, (int)nCellKey, 1, &m);
-  if( rc ){
-    return rc;
-  }
-
-  /* The index entry must begin with a header size */
-  (void)getVarint32((u8*)m.z, szHdr);
-  testcase( szHdr==3 );
-  testcase( szHdr==m.n );
-  if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
-    goto idx_rowid_corruption;
-  }
-
-  /* The last field of the index should be an integer - the ROWID.
-  ** Verify that the last entry really is an integer. */
-  (void)getVarint32((u8*)&m.z[szHdr-1], typeRowid);
-  testcase( typeRowid==1 );
-  testcase( typeRowid==2 );
-  testcase( typeRowid==3 );
-  testcase( typeRowid==4 );
-  testcase( typeRowid==5 );
-  testcase( typeRowid==6 );
-  testcase( typeRowid==8 );
-  testcase( typeRowid==9 );
-  if( unlikely(typeRowid<1 || typeRowid>9 || typeRowid==7) ){
-    goto idx_rowid_corruption;
-  }
-  lenRowid = sqlite3VdbeSerialTypeLen(typeRowid);
-  testcase( (u32)m.n==szHdr+lenRowid );
-  if( unlikely((u32)m.n<szHdr+lenRowid) ){
-    goto idx_rowid_corruption;
-  }
-
-  /* Fetch the integer off the end of the index record */
-  sqlite3VdbeSerialGet((u8*)&m.z[m.n-lenRowid], typeRowid, &v);
-  *rowid = v.u.i;
-  sqlite3VdbeMemRelease(&m);
-  return SQLITE_OK;
-
-  /* Jump here if database corruption is detected after m has been
-  ** allocated.  Free the m object and return SQLITE_CORRUPT. */
-idx_rowid_corruption:
-  testcase( m.zMalloc!=0 );
-  sqlite3VdbeMemRelease(&m);
-  return SQLITE_CORRUPT_BKPT;
-}
-
-/*
-** Compare the key of the index entry that cursor pC is pointing to against
-** the key string in pUnpacked.  Write into *pRes a number
-** that is negative, zero, or positive if pC is less than, equal to,
-** or greater than pUnpacked.  Return SQLITE_OK on success.
-**
-** pUnpacked is either created without a rowid or is truncated so that it
-** omits the rowid at the end.  The rowid at the end of the index entry
-** is ignored as well.  Hence, this routine only compares the prefixes 
-** of the keys prior to the final rowid, not the entire key.
-*/
-int sqlite3VdbeIdxKeyCompare(
-  VdbeCursor *pC,             /* The cursor to compare against */
-  UnpackedRecord *pUnpacked,  /* Unpacked version of key to compare against */
-  int *res                    /* Write the comparison result here */
-){
-  i64 nCellKey = 0;
-  int rc;
-  BtCursor *pCur = pC->pCursor;
-  Mem m;
-
-  assert( sqlite3BtreeCursorIsValid(pCur) );
-  rc = sqlite3BtreeKeySize(pCur, &nCellKey);
-  assert( rc==SQLITE_OK );    /* pCur is always valid so KeySize cannot fail */
-  /* nCellKey will always be between 0 and 0xffffffff because of the say
-  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
-  if( nCellKey<=0 || nCellKey>0x7fffffff ){
-    *res = 0;
-    return SQLITE_CORRUPT;
-  }
-  memset(&m, 0, sizeof(m));
-  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, (int)nCellKey, 1, &m);
-  if( rc ){
-    return rc;
-  }
-  assert( pUnpacked->flags & UNPACKED_IGNORE_ROWID );
-  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
-  sqlite3VdbeMemRelease(&m);
-  return SQLITE_OK;
-}
-
-/*
-** This routine sets the value to be returned by subsequent calls to
-** sqlite3_changes() on the database handle 'db'. 
-*/
-void sqlite3VdbeSetChanges(sqlite3 *db, int nChange){
-  assert( sqlite3_mutex_held(db->mutex) );
-  db->nChange = nChange;
-  db->nTotalChange += nChange;
-}
-
-/*
-** Set a flag in the vdbe to update the change counter when it is finalised
-** or reset.
-*/
-void sqlite3VdbeCountChanges(Vdbe *v){
-  v->changeCntOn = 1;
-}
-
-/*
-** Mark every prepared statement associated with a database connection
-** as expired.
-**
-** An expired statement means that recompilation of the statement is
-** recommend.  Statements expire when things happen that make their
-** programs obsolete.  Removing user-defined functions or collating
-** sequences, or changing an authorization function are the types of
-** things that make prepared statements obsolete.
-*/
-void sqlite3ExpirePreparedStatements(sqlite3 *db){
-  Vdbe *p;
-  for(p = db->pVdbe; p; p=p->pNext){
-    p->expired = 1;
-  }
-}
-
-/*
-** Return the database associated with the Vdbe.
-*/
-sqlite3 *sqlite3VdbeDb(Vdbe *v){
-  return v->db;
-}