openwrt_helloworld/shadowsocksr-libev/src/server/crc32.c
2022-04-17 03:50:24 +08:00

98 lines
2.5 KiB
C

static uint32_t crc32_table[256] = {0};
void init_crc32_table(void) {
uint32_t c, i, j;
if (crc32_table[0] == 0) {
for (i = 0; i < 256; i++) {
c = i;
for (j = 0; j < 8; j++) {
if (c & 1)
c = 0xedb88320L ^ (c >> 1);
else
c = c >> 1;
}
crc32_table[i] = c;
}
}
}
uint32_t crc32(unsigned char *buffer, unsigned int size) {
uint32_t crc = 0xFFFFFFFF;
unsigned int i;
for (i = 0; i < size; i++) {
crc = crc32_table[(crc ^ buffer[i]) & 0xFF] ^ (crc >> 8);
}
return crc ^ 0xFFFFFFFF;
}
void fillcrc32to(unsigned char *buffer, unsigned int size, unsigned char *outbuffer) {
uint32_t crc = 0xFFFFFFFF;
unsigned int i;
for (i = 0; i < size; i++) {
crc = crc32_table[(crc ^ buffer[i]) & 0xff] ^ (crc >> 8);
}
crc ^= 0xFFFFFFFF;
outbuffer[0] = crc;
outbuffer[1] = crc >> 8;
outbuffer[2] = crc >> 16;
outbuffer[3] = crc >> 24;
}
void fillcrc32(unsigned char *buffer, unsigned int size) {
uint32_t crc = 0xFFFFFFFF;
unsigned int i;
size -= 4;
for (i = 0; i < size; i++) {
crc = crc32_table[(crc ^ buffer[i]) & 0xff] ^ (crc >> 8);
}
buffer += size;
buffer[0] = crc;
buffer[1] = crc >> 8;
buffer[2] = crc >> 16;
buffer[3] = crc >> 24;
}
void adler32_short(unsigned char *buffer, unsigned int size, uint32_t *a, uint32_t *b) {
for (int i = 0; i < size; i++) {
*a += buffer[i];
*b += *a;
}
*a %= 65521;
*b %= 65521;
}
#define NMAX 5552
uint32_t adler32(unsigned char *buffer, unsigned int size) {
uint32_t a = 1;
uint32_t b = 0;
while ( size >= NMAX ) {
adler32_short(buffer, NMAX, &a, &b);
buffer += NMAX;
size -= NMAX;
}
adler32_short(buffer, size, &a, &b);
return (b << 16) + a;
}
#undef NMAX
void filladler32(unsigned char *buffer, unsigned int size) {
size -= 4;
uint32_t checksum = adler32(buffer, size);
buffer += size;
buffer[0] = checksum;
buffer[1] = checksum >> 8;
buffer[2] = checksum >> 16;
buffer[3] = checksum >> 24;
}
int checkadler32(unsigned char *buffer, unsigned int size) {
size -= 4;
uint32_t checksum = adler32(buffer, size);
buffer += size;
return checksum == (((uint32_t)buffer[3] << 24)
| ((uint32_t)buffer[2] << 16)
| ((uint32_t)buffer[1] << 8)
| (uint32_t)buffer[0]);
}