Mailbox bitlist generator

attacks.c

const char Vector[5][8] = {
    { +10, +11,  +1,  -9, -10, -11,  -1,  +9 }, // K
    { +10, +11,  +1,  -9, -10, -11,  -1,  +9 }, // Q
    { +10,  +1, -10,  -1,   0,   0,   0,   0 }, // R
    { +11,  -9, -11,  +9,   0,   0,   0,   0 }, // B
    { +21, +12,  -8, -19, -21, -12,  +8, +19 }  // N
};

const char Slide[5] = {
    0, 1, 1, 1, 0
};

void GenBitlistMailbox(struct Board * b, int tmp, int from, int piece)
{
    int dir = 0;

    while (dir < 8) {
        int inc = Vector[piece][dir];
        int dest = ToMailbox[from] + inc;
        int dest64 = FromMailbox[dest];

        if (!inc) break;

        while (dest64 != INVALID) {
            b->bitlist[dest64] ^= tmp;

            if (b->index[dest64] != INVALID || !Slide[piece])
                break;

            dest += inc;
            dest64 = FromMailbox[dest];
        }

        dir++;
    }
}