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FIX: legic_prng.c according to user on forum ref: http://www.proxmark.org/forum/viewtopic.php?pid=5437#p5437 needs to be "& 0x7F"

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ADD:  method for calculating the storage crc8.
This commit is contained in:
iceman1001 2016-02-12 12:34:05 +01:00
commit ee4e281675
3 changed files with 35 additions and 7 deletions
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29
common/crc.c
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@ -6,6 +6,8 @@
// Generic CRC calculation code.
//-----------------------------------------------------------------------------
#include "crc.h"
#include "util.h"
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
@ -21,8 +23,7 @@ void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, u
void crc_update(crc_t *crc, uint32_t data, int data_width)
{
int i;
for(i=0; i<data_width; i++) {
for( int i=0; i < data_width; i++) {
int oldstate = crc->state;
crc->state = crc->state >> 1;
if( (oldstate^data) & 1 ) {
@ -49,8 +50,28 @@ uint32_t CRC8Maxim(uint8_t *buff, size_t size)
crc_init(&crc, 9, 0x8c, 0x00, 0x00);
crc_clear(&crc);
for (size_t i=0; i < size; ++i){
for (size_t i=0; i < size; ++i)
crc_update(&crc, buff[i], 8);
}
return crc_finish(&crc);
}
uint32_t CRC8Legic(uint8_t *buff, size_t size) {
// Poly 0x63, reversed poly 0xC6, Init 0x55, Final 0x00
crc_t crc;
crc_init(&crc, 8, 0xC6, 0x55, 0);
crc_clear(&crc);
for ( int i = 0; i < size; ++i)
crc_update(&crc, buff[i], 8);
return SwapBits(crc_finish(&crc), 8);
}
uint32_t SwapBits(uint32_t value, int nrbits) {
uint32_t newvalue = 0;
for(int i = 0; i < nrbits; i++) {
newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
}
return newvalue;
}