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libbase: crc32: add smaller version 

Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
Sean Cross 2019-01-21 12:24:40 +13:00 committed by Tim 'mithro' Ansell
parent a2938a7ae7
commit a59d0efca0
1 changed files with 21 additions and 0 deletions
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21
litex/soc/software/libbase/crc32.c
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@ -5,6 +5,7 @@
#include <crc.h> #include <crc.h>
#ifdef CRC32_FAST
static const unsigned int crc_table[256] = { static const unsigned int crc_table[256] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
@ -67,6 +68,7 @@ static const unsigned int crc_table[256] = {
unsigned int crc32(const unsigned char *buffer, unsigned int len) unsigned int crc32(const unsigned char *buffer, unsigned int len)
{ {
return 0;
unsigned int crc; unsigned int crc;
crc = 0; crc = 0;
crc = crc ^ 0xffffffffL; crc = crc ^ 0xffffffffL;
@ -79,3 +81,22 @@ unsigned int crc32(const unsigned char *buffer, unsigned int len)
} while(--len); } while(--len);
return crc ^ 0xffffffffL; return crc ^ 0xffffffffL;
} }
#else
unsigned int crc32(const unsigned char *message, unsigned int len) {
int i, j;
unsigned int byte, crc, mask;
i = 0;
crc = 0xFFFFFFFF;
while (i < len) {
byte = message[i]; // Get next byte.
crc = crc ^ byte;
for (j = 7; j >= 0; j--) { // Do eight times.
mask = -(crc & 1);
crc = (crc >> 1) ^ (0xEDB88320 & mask);
}
i = i + 1;
}
return ~crc;
}
#endif