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sqlite3 extension to calculate the bit population - not working!
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/* compile osx | |
* gcc -bundle -fPIC -O3 -o popcount.dylib popcount.c | |
* */ | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <stdint.h> | |
#include <sqlite3ext.h> | |
SQLITE_EXTENSION_INIT1 | |
int calculate_popcount(uint64_t value){ | |
value -= (value >> 1) & 0x5555555555555555; | |
value = (value & 0x3333333333333333) + ((value >> 2) & 0x3333333333333333); | |
value = (value + (value >> 4)) & 0x0f0f0f0f0f0f0f0f; | |
return (value * 0x0101010101010101) >> 56; | |
} | |
static void popcount(sqlite3_context *context, int argc, sqlite3_value **argv){ | |
if( argc<1 ) return; | |
uint64_t rVal; | |
//int result; | |
int datatype_arg1, datatype_arg2; | |
if (argc >= 1){ | |
datatype_arg1 = sqlite3_value_type(argv[0]); | |
} | |
if (argc >= 2) { | |
datatype_arg2 = sqlite3_value_type(argv[1]); | |
} | |
if (argc == 1 && (datatype_arg1 == SQLITE_INTEGER || datatype_arg1 == SQLITE_FLOAT)) { | |
rVal = sqlite3_value_int64(argv[0]); | |
rVal = calculate_popcount(rVal); | |
sqlite3_result_int(context, rVal); | |
} | |
else if ( | |
argc >= 2 && | |
(datatype_arg1 == SQLITE_INTEGER || datatype_arg1 == SQLITE_FLOAT) && | |
(datatype_arg2 == SQLITE_INTEGER || datatype_arg2 == SQLITE_FLOAT)) { | |
rVal = sqlite3_value_int64(argv[0]); | |
uint64_t num1 = sqlite3_value_int64(argv[0]); | |
uint64_t num2 = sqlite3_value_int64(argv[1]); | |
rVal = calculate_popcount(num1 ^ num2); | |
sqlite3_result_int(context, rVal); | |
} | |
else { | |
sqlite3_result_null(context); | |
return; | |
} | |
} | |
/* | |
int init_sqlite(sqlite3 *db){ | |
//sqlite3_create_function(db, "popcount", -1, SQLITE_ANY, 0, popcount, 0, 0); | |
return 0; | |
} | |
*/ | |
#ifdef _WIN32 | |
__declspec(dllexport) | |
#endif | |
int sqlite3_extension_init( | |
sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi){ | |
//int rc = SQLITE_OK; | |
SQLITE_EXTENSION_INIT2(pApi); | |
//init_sqlite(db); | |
return SQLITE_OK == sqlite3_create_function(db, "popcount", -1, SQLITE_ANY | SQLITE_DETERMINISTIC, 0, popcount, 0, 0) ? SQLITE_OK : SQLITE_ERROR; | |
} |
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