Function altivec_packIntArrayToCharArray

libswscale/ppc/swscale_altivec_template.c:26–86

#define vzero vec_splat_s32(0)

static inline void
altivec_packIntArrayToCharArray(int *val, uint8_t* dest, int dstW)
{
    register int i;
    vector unsigned int altivec_vectorShiftInt19 =
        vec_add(vec_splat_u32(10), vec_splat_u32(9));
    if ((unsigned long)dest % 16) {
        /* badly aligned store, we force store alignment */
        /* and will handle load misalignment on val w/ vec_perm */
        vector unsigned char perm1;
        vector signed int v1;
        for (i = 0 ; (i < dstW) &&
            (((unsigned long)dest + i) % 16) ; i++) {
                int t = val[i] >> 19;
                dest[i] = (t < 0) ? 0 : ((t > 255) ? 255 : t);
        }
        perm1 = vec_lvsl(i << 2, val);
        v1 = vec_ld(i << 2, val);
        for ( ; i < (dstW - 15); i+=16) {
            int offset = i << 2;
            vector signed int v2 = vec_ld(offset + 16, val);
            vector signed int v3 = vec_ld(offset + 32, val);
            vector signed int v4 = vec_ld(offset + 48, val);
            vector signed int v5 = vec_ld(offset + 64, val);
            vector signed int v12 = vec_perm(v1, v2, perm1);
            vector signed int v23 = vec_perm(v2, v3, perm1);
            vector signed int v34 = vec_perm(v3, v4, perm1);
            vector signed int v45 = vec_perm(v4, v5, perm1);

            vector signed int vA = vec_sra(v12, altivec_vectorShiftInt19);
            vector signed int vB = vec_sra(v23, altivec_vectorShiftInt19);
            vector signed int vC = vec_sra(v34, altivec_vectorShiftInt19);
            vector signed int vD = vec_sra(v45, altivec_vectorShiftInt19);
            vector unsigned short vs1 = vec_packsu(vA, vB);
            vector unsigned short vs2 = vec_packsu(vC, vD);
            vector unsigned char vf = vec_packsu(vs1, vs2);
            vec_st(vf, i, dest);
            v1 = v5;
        }
    } else { // dest is properly aligned, great
        for (i = 0; i < (dstW - 15); i+=16) {
            int offset = i << 2;
            vector signed int v1 = vec_ld(offset, val);
            vector signed int v2 = vec_ld(offset + 16, val);
            vector signed int v3 = vec_ld(offset + 32, val);
            vector signed int v4 = vec_ld(offset + 48, val);
            vector signed int v5 = vec_sra(v1, altivec_vectorShiftInt19);
            vector signed int v6 = vec_sra(v2, altivec_vectorShiftInt19);
            vector signed int v7 = vec_sra(v3, altivec_vectorShiftInt19);
            vector signed int v8 = vec_sra(v4, altivec_vectorShiftInt19);
            vector unsigned short vs1 = vec_packsu(v5, v6);
            vector unsigned short vs2 = vec_packsu(v7, v8);
            vector unsigned char vf = vec_packsu(vs1, vs2);
            vec_st(vf, i, dest);
        }
    }
    for ( ; i < dstW ; i++) {
        int t = val[i] >> 19;