isa-l/raid/raid_base.c

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      contributors may be used to endorse or promote products derived
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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;
}