Index: third_party/sqlite/src/tool/logest.c |
diff --git a/third_party/sqlite/src/tool/logest.c b/third_party/sqlite/src/tool/logest.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..347fa68a4f4ee5a4cb72a8748fa7f1a60cbcb022 |
--- /dev/null |
+++ b/third_party/sqlite/src/tool/logest.c |
@@ -0,0 +1,170 @@ |
+/* |
+** 2013-06-10 |
+** |
+** 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 a simple command-line utility for converting from |
+** integers and LogEst values and back again and for doing simple |
+** arithmetic operations (multiple and add) on LogEst values. |
+** |
+** Usage: |
+** |
+** ./LogEst ARGS |
+** |
+** See the showHelp() routine for a description of valid arguments. |
+** Examples: |
+** |
+** To convert 123 from LogEst to integer: |
+** |
+** ./LogEst ^123 |
+** |
+** To convert 123456 from integer to LogEst: |
+** |
+** ./LogEst 123456 |
+** |
+*/ |
+#include <stdio.h> |
+#include <stdlib.h> |
+#include <ctype.h> |
+#include <assert.h> |
+#include <string.h> |
+#include "sqlite3.h" |
+ |
+typedef short int LogEst; /* 10 times log2() */ |
+ |
+LogEst logEstMultiply(LogEst a, LogEst b){ return a+b; } |
+LogEst logEstAdd(LogEst a, LogEst b){ |
+ static const unsigned char x[] = { |
+ 10, 10, /* 0,1 */ |
+ 9, 9, /* 2,3 */ |
+ 8, 8, /* 4,5 */ |
+ 7, 7, 7, /* 6,7,8 */ |
+ 6, 6, 6, /* 9,10,11 */ |
+ 5, 5, 5, /* 12-14 */ |
+ 4, 4, 4, 4, /* 15-18 */ |
+ 3, 3, 3, 3, 3, 3, /* 19-24 */ |
+ 2, 2, 2, 2, 2, 2, 2, /* 25-31 */ |
+ }; |
+ if( a<b ){ LogEst t = a; a = b; b = t; } |
+ if( a>b+49 ) return a; |
+ if( a>b+31 ) return a+1; |
+ return a+x[a-b]; |
+} |
+LogEst logEstFromInteger(sqlite3_uint64 x){ |
+ static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 }; |
+ LogEst y = 40; |
+ if( x<8 ){ |
+ if( x<2 ) return 0; |
+ while( x<8 ){ y -= 10; x <<= 1; } |
+ }else{ |
+ while( x>255 ){ y += 40; x >>= 4; } |
+ while( x>15 ){ y += 10; x >>= 1; } |
+ } |
+ return a[x&7] + y - 10; |
+} |
+static sqlite3_uint64 logEstToInt(LogEst x){ |
+ sqlite3_uint64 n; |
+ if( x<10 ) return 1; |
+ n = x%10; |
+ x /= 10; |
+ if( n>=5 ) n -= 2; |
+ else if( n>=1 ) n -= 1; |
+ if( x>=3 ) return (n+8)<<(x-3); |
+ return (n+8)>>(3-x); |
+} |
+static LogEst logEstFromDouble(double x){ |
+ sqlite3_uint64 a; |
+ LogEst e; |
+ assert( sizeof(x)==8 && sizeof(a)==8 ); |
+ if( x<=0.0 ) return -32768; |
+ if( x<0.01 ) return -logEstFromDouble(1.0/x); |
+ if( x<1.0 ) return logEstFromDouble(100.0*x) - 66; |
+ if( x<1024.0 ) return logEstFromInteger((sqlite3_uint64)(1024.0*x)) - 100; |
+ if( x<=2000000000.0 ) return logEstFromInteger((sqlite3_uint64)x); |
+ memcpy(&a, &x, 8); |
+ e = (a>>52) - 1022; |
+ return e*10; |
+} |
+ |
+int isInteger(const char *z){ |
+ while( z[0]>='0' && z[0]<='9' ) z++; |
+ return z[0]==0; |
+} |
+ |
+int isFloat(const char *z){ |
+ char c; |
+ while( ((c=z[0])>='0' && c<='9') || c=='.' || c=='E' || c=='e' |
+ || c=='+' || c=='-' ) z++; |
+ return z[0]==0; |
+} |
+ |
+static void showHelp(const char *zArgv0){ |
+ printf("Usage: %s ARGS...\n", zArgv0); |
+ printf("Arguments:\n" |
+ " NUM Convert NUM from integer to LogEst and push onto the stack\n" |
+ " ^NUM Interpret NUM as a LogEst and push onto stack\n" |
+ " x Multiple the top two elements of the stack\n" |
+ " + Add the top two elements of the stack\n" |
+ " dup Dupliate the top element on the stack\n" |
+ " inv Take the reciprocal of the top of stack. N = 1/N.\n" |
+ " log Find the LogEst of the number on top of stack\n" |
+ " nlogn Compute NlogN where N is the top of stack\n" |
+ ); |
+ exit(1); |
+} |
+ |
+int main(int argc, char **argv){ |
+ int i; |
+ int n = 0; |
+ LogEst a[100]; |
+ for(i=1; i<argc; i++){ |
+ const char *z = argv[i]; |
+ if( strcmp(z,"+")==0 ){ |
+ if( n>=2 ){ |
+ a[n-2] = logEstAdd(a[n-2],a[n-1]); |
+ n--; |
+ } |
+ }else if( strcmp(z,"x")==0 ){ |
+ if( n>=2 ){ |
+ a[n-2] = logEstMultiply(a[n-2],a[n-1]); |
+ n--; |
+ } |
+ }else if( strcmp(z,"dup")==0 ){ |
+ if( n>0 ){ |
+ a[n] = a[n-1]; |
+ n++; |
+ } |
+ }else if( strcmp(z,"log")==0 ){ |
+ if( n>0 ) a[n-1] = logEstFromInteger(a[n-1]) - 33; |
+ }else if( strcmp(z,"nlogn")==0 ){ |
+ if( n>0 ) a[n-1] += logEstFromInteger(a[n-1]) - 33; |
+ }else if( strcmp(z,"inv")==0 ){ |
+ if( n>0 ) a[n-1] = -a[n-1]; |
+ }else if( z[0]=='^' ){ |
+ a[n++] = atoi(z+1); |
+ }else if( isInteger(z) ){ |
+ a[n++] = logEstFromInteger(atoi(z)); |
+ }else if( isFloat(z) && z[0]!='-' ){ |
+ a[n++] = logEstFromDouble(atof(z)); |
+ }else{ |
+ showHelp(argv[0]); |
+ } |
+ } |
+ for(i=n-1; i>=0; i--){ |
+ if( a[i]<-40 ){ |
+ printf("%5d (%f)\n", a[i], 1.0/(double)logEstToInt(-a[i])); |
+ }else if( a[i]<10 ){ |
+ printf("%5d (%f)\n", a[i], logEstToInt(a[i]+100)/1024.0); |
+ }else{ |
+ sqlite3_uint64 x = logEstToInt(a[i]+100)*100/1024; |
+ printf("%5d (%lld.%02lld)\n", a[i], x/100, x%100); |
+ } |
+ } |
+ return 0; |
+} |