third_party/sqlite/sqlite-src-3080704/ext/misc/compress.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, 2 months ago

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1 /*

2 ** 2014-06-13

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 SQL compression functions

14 ** compress() and uncompress() using ZLIB.

15 */

16 #include "sqlite3ext.h"

17 SQLITE_EXTENSION_INIT1

18 #include <zlib.h>

19

20 /*

21 ** Implementation of the "compress(X)" SQL function. The input X is

22 ** compressed using zLib and the output is returned.

23 **

24 ** The output is a BLOB that begins with a variable-length integer that

25 ** is the input size in bytes (the size of X before compression). The

26 ** variable-length integer is implemented as 1 to 5 bytes. There are

27 ** seven bits per integer stored in the lower seven bits of each byte.

28 ** More significant bits occur first. The most significant bit (0x80)

29 ** is a flag to indicate the end of the integer.

30 */

31 static void compressFunc(

32 sqlite3_context *context,

33 int argc,

34 sqlite3_value **argv

35 ){

36 const unsigned char *pIn;

37 unsigned char *pOut;

38 unsigned int nIn;

39 unsigned long int nOut;

40 unsigned char x[8];

41 int i, j;

42

43 pIn = sqlite3_value_blob(argv[0]);

44 nIn = sqlite3_value_bytes(argv[0]);

45 nOut = 13 + nIn + (nIn+999)/1000;

46 pOut = sqlite3_malloc( nOut+5 );

47 for(i=4; i>=0; i--){

48 x[i] = (nIn >> (7*(4-i)))&0x7f;

49 }

50 for(i=0; i<4 && x[i]==0; i++){}

51 for(j=0; i<=4; i++, j++) pOut[j] = x[i];

52 pOut[j-1] \|= 0x80;

53 compress(&pOut[j], &nOut, pIn, nIn);

54 sqlite3_result_blob(context, pOut, nOut+j, sqlite3_free);

55 }

56

57 /*

58 ** Implementation of the "uncompress(X)" SQL function. The argument X

59 ** is a blob which was obtained from compress(Y). The output will be

60 ** the value Y.

61 */

62 static void uncompressFunc(

63 sqlite3_context *context,

64 int argc,

65 sqlite3_value **argv

66 ){

67 const unsigned char *pIn;

68 unsigned char *pOut;

69 unsigned int nIn;

70 unsigned long int nOut;

71 int rc;

72 int i;

73

74 pIn = sqlite3_value_blob(argv[0]);

75 nIn = sqlite3_value_bytes(argv[0]);

76 nOut = 0;

77 for(i=0; i<nIn && i<5; i++){

78 nOut = (nOut<<7) \| (pIn[i]&0x7f);

79 if( (pIn[i]&0x80)!=0 ){ i++; break; }

80 }

81 pOut = sqlite3_malloc( nOut+1 );

82 rc = uncompress(pOut, &nOut, &pIn[i], nIn-i);

83 if( rc==Z_OK ){

84 sqlite3_result_blob(context, pOut, nOut, sqlite3_free);

85 }

86 }

87

88

89 #ifdef _WIN32

90 __declspec(dllexport)

91 #endif

92 int sqlite3_compress_init(

93 sqlite3 *db,

94 char **pzErrMsg,

95 const sqlite3_api_routines *pApi

96 ){

97 int rc = SQLITE_OK;

98 SQLITE_EXTENSION_INIT2(pApi);

99 (void)pzErrMsg; /* Unused parameter */

100 rc = sqlite3_create_function(db, "compress", 1, SQLITE_UTF8, 0,

101 compressFunc, 0, 0);

102 if( rc==SQLITE_OK ){

103 rc = sqlite3_create_function(db, "uncompress", 1, SQLITE_UTF8, 0,

104 uncompressFunc, 0, 0);

105 }

106 return rc;

107 }

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