segatools2/util/crc.c

29 lines
474 B
C

#include <stddef.h>
#include <stdint.h>
#include "util/crc.h"
uint32_t crc32(const void *src, size_t nbytes, uint32_t in)
{
const uint8_t *bytes;
uint32_t crc;
size_t i;
bytes = src;
crc = ~in;
for (i = 0 ; i < nbytes * 8 ; i++) {
if (i % 8 == 0) {
crc ^= *bytes++;
}
if (crc & 1) {
crc = (crc >> 1) ^ 0xEDB88320;
} else {
crc = (crc >> 1);
}
}
return ~crc;
}