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| 1 /* | |
| 2 ** 2013-04-17 | |
| 3 ** | |
| 4 ** The author disclaims copyright to this source code. In place of | |
| 5 ** a legal notice, here is a blessing: | |
| 6 ** | |
| 7 ** May you do good and not evil. | |
| 8 ** May you find forgiveness for yourself and forgive others. | |
| 9 ** May you share freely, never taking more than you give. | |
| 10 ** | |
| 11 ****************************************************************************** | |
| 12 ** | |
| 13 ** This SQLite extension implements functions for the exact display | |
| 14 ** and input of IEEE754 Binary64 floating-point numbers. | |
| 15 ** | |
| 16 ** ieee754(X) | |
| 17 ** ieee754(Y,Z) | |
| 18 ** | |
| 19 ** In the first form, the value X should be a floating-point number. | |
| 20 ** The function will return a string of the form 'ieee754(Y,Z)' where | |
| 21 ** Y and Z are integers such that X==Y*pow(2,Z). | |
| 22 ** | |
| 23 ** In the second form, Y and Z are integers which are the mantissa and | |
| 24 ** base-2 exponent of a new floating point number. The function returns | |
| 25 ** a floating-point value equal to Y*pow(2,Z). | |
| 26 ** | |
| 27 ** Examples: | |
| 28 ** | |
| 29 ** ieee754(2.0) -> 'ieee754(2,0)' | |
| 30 ** ieee754(45.25) -> 'ieee754(181,-2)' | |
| 31 ** ieee754(2, 0) -> 2.0 | |
| 32 ** ieee754(181, -2) -> 45.25 | |
| 33 */ | |
| 34 #include "sqlite3ext.h" | |
| 35 SQLITE_EXTENSION_INIT1 | |
| 36 #include <assert.h> | |
| 37 #include <string.h> | |
| 38 | |
| 39 /* | |
| 40 ** Implementation of the ieee754() function | |
| 41 */ | |
| 42 static void ieee754func( | |
| 43 sqlite3_context *context, | |
| 44 int argc, | |
| 45 sqlite3_value **argv | |
| 46 ){ | |
| 47 if( argc==1 ){ | |
| 48 sqlite3_int64 m, a; | |
| 49 double r; | |
| 50 int e; | |
| 51 int isNeg; | |
| 52 char zResult[100]; | |
| 53 assert( sizeof(m)==sizeof(r) ); | |
| 54 if( sqlite3_value_type(argv[0])!=SQLITE_FLOAT ) return; | |
| 55 r = sqlite3_value_double(argv[0]); | |
| 56 if( r<0.0 ){ | |
| 57 isNeg = 1; | |
| 58 r = -r; | |
| 59 }else{ | |
| 60 isNeg = 0; | |
| 61 } | |
| 62 memcpy(&a,&r,sizeof(a)); | |
| 63 if( a==0 ){ | |
| 64 e = 0; | |
| 65 m = 0; | |
| 66 }else{ | |
| 67 e = a>>52; | |
| 68 m = a & ((((sqlite3_int64)1)<<52)-1); | |
| 69 m |= ((sqlite3_int64)1)<<52; | |
| 70 while( e<1075 && m>0 && (m&1)==0 ){ | |
| 71 m >>= 1; | |
| 72 e++; | |
| 73 } | |
| 74 if( isNeg ) m = -m; | |
| 75 } | |
| 76 sqlite3_snprintf(sizeof(zResult), zResult, "ieee754(%lld,%d)", | |
| 77 m, e-1075); | |
| 78 sqlite3_result_text(context, zResult, -1, SQLITE_TRANSIENT); | |
| 79 }else if( argc==2 ){ | |
| 80 sqlite3_int64 m, e, a; | |
| 81 double r; | |
| 82 int isNeg = 0; | |
| 83 m = sqlite3_value_int64(argv[0]); | |
| 84 e = sqlite3_value_int64(argv[1]); | |
| 85 if( m<0 ){ | |
| 86 isNeg = 1; | |
| 87 m = -m; | |
| 88 if( m<0 ) return; | |
| 89 }else if( m==0 && e>1000 && e<1000 ){ | |
| 90 sqlite3_result_double(context, 0.0); | |
| 91 return; | |
| 92 } | |
| 93 while( (m>>32)&0xffe00000 ){ | |
| 94 m >>= 1; | |
| 95 e++; | |
| 96 } | |
| 97 while( m!=0 && ((m>>32)&0xfff00000)==0 ){ | |
| 98 m <<= 1; | |
| 99 e--; | |
| 100 } | |
| 101 e += 1075; | |
| 102 if( e<0 ) e = m = 0; | |
| 103 if( e>0x7ff ) e = 0x7ff; | |
| 104 a = m & ((((sqlite3_int64)1)<<52)-1); | |
| 105 a |= e<<52; | |
| 106 if( isNeg ) a |= ((sqlite3_uint64)1)<<63; | |
| 107 memcpy(&r, &a, sizeof(r)); | |
| 108 sqlite3_result_double(context, r); | |
| 109 } | |
| 110 } | |
| 111 | |
| 112 | |
| 113 #ifdef _WIN32 | |
| 114 __declspec(dllexport) | |
| 115 #endif | |
| 116 int sqlite3_ieee_init( | |
| 117 sqlite3 *db, | |
| 118 char **pzErrMsg, | |
| 119 const sqlite3_api_routines *pApi | |
| 120 ){ | |
| 121 int rc = SQLITE_OK; | |
| 122 SQLITE_EXTENSION_INIT2(pApi); | |
| 123 (void)pzErrMsg; /* Unused parameter */ | |
| 124 rc = sqlite3_create_function(db, "ieee754", 1, SQLITE_UTF8, 0, | |
| 125 ieee754func, 0, 0); | |
| 126 if( rc==SQLITE_OK ){ | |
| 127 rc = sqlite3_create_function(db, "ieee754", 2, SQLITE_UTF8, 0, | |
| 128 ieee754func, 0, 0); | |
| 129 } | |
| 130 return rc; | |
| 131 } | |
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Chromium Code Reviews
Issue 2846743003:
[sql] Remove SQLite 3.10.2 reference directory. (Closed)
