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libbase: crc16: commit smaller version of crc16 

Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
Sean Cross 2019-01-21 12:25:01 +13:00 committed by Tim 'mithro' Ansell
parent a59d0efca0
commit c0e723868e
1 changed files with 14 additions and 1 deletions
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15
litex/soc/software/libbase/crc16.c
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@ -1,5 +1,5 @@
#include <crc.h>
#ifdef CRC16_FAST
static const unsigned int crc16_table[256] = {
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
@ -45,3 +45,16 @@ unsigned short crc16(const unsigned char *buffer, int len)
return crc;
}
#else
unsigned short crc16(const unsigned char* data_p, int length) {
unsigned char x;
unsigned short crc = 0;
while (length--){
x = crc >> 8 ^ *data_p++;
x ^= x>>4;
crc = (crc << 8) ^ ((unsigned short)(x << 12)) ^ ((unsigned short)(x <<5)) ^ ((unsigned short)x);
}
return crc;
}
#endif