third_party/sqlite/sqlite-src-3080704/ext/misc/ieee754.c - Issue 2363173002: [sqlite] Remove obsolete reference version 3.8.7.4.

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Issue 2363173002: [sqlite] Remove obsolete reference version 3.8.7.4. (Closed)

Patch Set: Created 4 years, 3 months ago

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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>>32)&0xfff00000)==0 ){

98 m <<= 1;

99 e--;

100 }

101 e += 1075;

102 if( e<0 ) e = m = 0;

103 if( e>0x7ff ) m = 0;

104 a = m & ((((sqlite3_int64)1)<<52)-1);

105 a \|= e<<52;

106 if( isNeg ) a \|= ((sqlite3_int64)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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