[proxmark3-svn] / common / crc.c

/*
 * crc.c
 *
 * Generic CRC calculation code.
 * 
 */

#include "crc.h"

void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor)
{
	crc->order = order;
	crc->polynom = polynom;
	crc->initial_value = initial_value;
	crc->final_xor = final_xor;
	crc->mask = (1L<<order)-1;
	crc_clear(crc);
}

void crc_update(crc_t *crc, uint32_t data, int data_width)
{
	int i;
	for(i=0; i<data_width; i++) {
		int oldstate = crc->state;
		crc->state = crc->state >> 1;
		if( (oldstate^data) & 1 ) {
			crc->state ^= crc->polynom;
		}
		data >>= 1;
	}
}

void crc_clear(crc_t *crc)
{
	crc->state = crc->initial_value & crc->mask;
}

uint32_t crc_finish(crc_t *crc)
{
	return ( crc->state ^ crc->final_xor ) & crc->mask;
}
Commit	Line	Data
68d9d60a	1	/*
	2	* crc.c
	3	*
	4	* Generic CRC calculation code.
	5	*
	6	*/
	7
	8	#include "crc.h"
	9
	10	void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor)
	11	{
	12	crc->order = order;
	13	crc->polynom = polynom;
	14	crc->initial_value = initial_value;
	15	crc->final_xor = final_xor;
	16	crc->mask = (1L<<order)-1;
	17	crc_clear(crc);
	18	}
	19
	20	void crc_update(crc_t *crc, uint32_t data, int data_width)
	21	{
	22	int i;
	23	for(i=0; i<data_width; i++) {
	24	int oldstate = crc->state;
	25	crc->state = crc->state >> 1;
	26	if( (oldstate^data) & 1 ) {
	27	crc->state ^= crc->polynom;
	28	}
	29	data >>= 1;
	30	}
	31	}
	32
	33	void crc_clear(crc_t *crc)
	34	{
	35	crc->state = crc->initial_value & crc->mask;
	36	}
	37
	38	uint32_t crc_finish(crc_t *crc)
	39	{
	40	return ( crc->state ^ crc->final_xor ) & crc->mask;
	41	}