isa-l/raid/raid_base.c

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  are met:
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#include <limits.h>
#include <stdint.h>

#if __WORDSIZE == 64 || _WIN64 || __x86_64__
# define notbit0 0xfefefefefefefefeULL
# define bit7    0x8080808080808080ULL
# define gf8poly 0x1d1d1d1d1d1d1d1dULL
#else
# define notbit0 0xfefefefeUL
# define bit7    0x80808080UL
# define gf8poly 0x1d1d1d1dUL
#endif

int pq_gen_base(int vects, int len, void **array)
{
	int i, j;
	unsigned long p, q, s;
	unsigned long **src = (unsigned long **)array;
	int blocks = len / sizeof(long);

	if (vects < 4)
		return 1;	// Must have at least 2 src and 2 dest

	for (i = 0; i < blocks; i++) {
		q = p = src[vects - 3][i];

		for (j = vects - 4; j >= 0; j--) {
			p ^= s = src[j][i];
			q = s ^ (((q << 1) & notbit0) ^	// shift each byte
				 ((((q & bit7) << 1) - ((q & bit7) >> 7))	// mask out bytes
				  & gf8poly));	// apply poly
		}

		src[vects - 2][i] = p;	// second to last pointer is p
		src[vects - 1][i] = q;	// last pointer is q
	}
	return 0;
}

int pq_check_base(int vects, int len, void **array)
{
	int i, j;
	unsigned char p, q, s;
	unsigned char **src = (unsigned char **)array;

	if (vects < 4)
		return 1;	// Must have at least 2 src and 2 dest

	for (i = 0; i < len; i++) {
		q = p = src[vects - 3][i];

		for (j = vects - 4; j >= 0; j--) {
			s = src[j][i];
			p ^= s;

			// mult by GF{2}
			q = s ^ ((q << 1) ^ ((q & 0x80) ? 0x1d : 0));
		}

		if (src[vects - 2][i] != p)	// second to last pointer is p
			return i | 1;
		if (src[vects - 1][i] != q)	// last pointer is q
			return i | 2;
	}
	return 0;
}

int xor_gen_base(int vects, int len, void **array)
{
	int i, j;
	unsigned char parity;
	unsigned char **src = (unsigned char **)array;

	if (vects < 3)
		return 1;	// Must have at least 2 src and 1 dest

	for (i = 0; i < len; i++) {
		parity = src[0][i];
		for (j = 1; j < vects - 1; j++)
			parity ^= src[j][i];

		src[vects - 1][i] = parity;	// last pointer is dest

	}

	return 0;
}

int xor_check_base(int vects, int len, void **array)
{
	int i, j, fail = 0;

	unsigned char parity;
	unsigned char **src = (unsigned char **)array;

	if (vects < 2)
		return 1;	// Must have at least 2 src

	for (i = 0; i < len; i++) {
		parity = 0;
		for (j = 0; j < vects; j++)
			parity ^= src[j][i];

		if (parity != 0) {
			fail = 1;
			break;
		}
	}
	if (fail && len > 0)
		return len;
	return fail;
}