static void hScale_altivec_real(SwsContext *c, int16_t *dst, int dstW,

                                const uint8_t *src, const int16_t *filter,

                                const int16_t *filterPos, int filterSize)

{

    register int i;

    DECLARE_ALIGNED(16, int, tempo)[4];



    if (filterSize % 4) {

        for (i = 0; i < dstW; i++) {

            register int j;

            register int srcPos = filterPos[i];

            register int val    = 0;

            for (j = 0; j < filterSize; j++)

                val += ((int)src[srcPos + j]) * filter[filterSize * i + j];

            dst[i] = FFMIN(val >> 7, (1 << 15) - 1);

        }

    } else

        switch (filterSize) {

        case 4:

            for (i = 0; i < dstW; i++) {

                register int srcPos = filterPos[i];



                vector unsigned char src_v0 = vec_ld(srcPos, src);

                vector unsigned char src_v1, src_vF;

                vector signed short src_v, filter_v;

                vector signed int val_vEven, val_s;

                if ((((uintptr_t)src + srcPos) % 16) > 12) {

                    src_v1 = vec_ld(srcPos + 16, src);

                }

                src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));



                src_v = // vec_unpackh sign-extends...

                        (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));

                // now put our elements in the even slots

                src_v = vec_mergeh(src_v, (vector signed short)vzero);



                filter_v = vec_ld(i << 3, filter);

                // The 3 above is 2 (filterSize == 4) + 1 (sizeof(short) == 2).



                // The neat trick: We only care for half the elements,

                // high or low depending on (i<<3)%16 (it's 0 or 8 here),

                // and we're going to use vec_mule, so we choose

                // carefully how to "unpack" the elements into the even slots.

                if ((i << 3) % 16)

                    filter_v = vec_mergel(filter_v, (vector signed short)vzero);

                else

                    filter_v = vec_mergeh(filter_v, (vector signed short)vzero);



                val_vEven = vec_mule(src_v, filter_v);

                val_s     = vec_sums(val_vEven, vzero);

                vec_st(val_s, 0, tempo);

                dst[i] = FFMIN(tempo[3] >> 7, (1 << 15) - 1);

            }

        break;



        case 8:

            for (i = 0; i < dstW; i++) {

                register int srcPos = filterPos[i];



                vector unsigned char src_v0 = vec_ld(srcPos, src);

                vector unsigned char src_v1, src_vF;

                vector signed short src_v, filter_v;

                vector signed int val_v, val_s;

                if ((((uintptr_t)src + srcPos) % 16) > 8) {

                    src_v1 = vec_ld(srcPos + 16, src);

                }

                src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));



                src_v = // vec_unpackh sign-extends...

                        (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));

                filter_v = vec_ld(i << 4, filter);

                // the 4 above is 3 (filterSize == 8) + 1 (sizeof(short) == 2)



                val_v = vec_msums(src_v, filter_v, (vector signed int)vzero);

                val_s = vec_sums(val_v, vzero);

                vec_st(val_s, 0, tempo);

                dst[i] = FFMIN(tempo[3] >> 7, (1 << 15) - 1);

            }

        break;



        case 16:

            for (i = 0; i < dstW; i++) {

                register int srcPos = filterPos[i];



                vector unsigned char src_v0 = vec_ld(srcPos, src);

                vector unsigned char src_v1 = vec_ld(srcPos + 16, src);

                vector unsigned char src_vF = vec_perm(src_v0, src_v1, vec_lvsl(srcPos, src));



                vector signed short src_vA = // vec_unpackh sign-extends...

                                             (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));

                vector signed short src_vB = // vec_unpackh sign-extends...

                                             (vector signed short)(vec_mergel((vector unsigned char)vzero, src_vF));



                vector signed short filter_v0 = vec_ld(i << 5, filter);

                vector signed short filter_v1 = vec_ld((i << 5) + 16, filter);

                // the 5 above are 4 (filterSize == 16) + 1 (sizeof(short) == 2)



                vector signed int val_acc = vec_msums(src_vA, filter_v0, (vector signed int)vzero);

                vector signed int val_v   = vec_msums(src_vB, filter_v1, val_acc);



                vector signed int val_s = vec_sums(val_v, vzero);



                vec_st(val_s, 0, tempo);

                dst[i] = FFMIN(tempo[3] >> 7, (1 << 15) - 1);

            }

        break;



        default:

            for (i = 0; i < dstW; i++) {

                register int j;

                register int srcPos = filterPos[i];



                vector signed int val_s, val_v = (vector signed int)vzero;

                vector signed short filter_v0R = vec_ld(i * 2 * filterSize, filter);

                vector unsigned char permF     = vec_lvsl((i * 2 * filterSize), filter);



                vector unsigned char src_v0 = vec_ld(srcPos, src);

                vector unsigned char permS  = vec_lvsl(srcPos, src);



                for (j = 0; j < filterSize - 15; j += 16) {

                    vector unsigned char src_v1 = vec_ld(srcPos + j + 16, src);

                    vector unsigned char src_vF = vec_perm(src_v0, src_v1, permS);



                    vector signed short src_vA = // vec_unpackh sign-extends...

                                                 (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));

                    vector signed short src_vB = // vec_unpackh sign-extends...

                                                 (vector signed short)(vec_mergel((vector unsigned char)vzero, src_vF));



                    vector signed short filter_v1R = vec_ld((i * 2 * filterSize) + (j * 2) + 16, filter);

                    vector signed short filter_v2R = vec_ld((i * 2 * filterSize) + (j * 2) + 32, filter);

                    vector signed short filter_v0  = vec_perm(filter_v0R, filter_v1R, permF);

                    vector signed short filter_v1  = vec_perm(filter_v1R, filter_v2R, permF);



                    vector signed int val_acc = vec_msums(src_vA, filter_v0, val_v);

                    val_v = vec_msums(src_vB, filter_v1, val_acc);



                    filter_v0R = filter_v2R;

                    src_v0     = src_v1;

                }



                if (j < filterSize - 7) {

                    // loading src_v0 is useless, it's already done above

                    // vector unsigned char src_v0 = vec_ld(srcPos + j, src);

                    vector unsigned char src_v1, src_vF;

                    vector signed short src_v, filter_v1R, filter_v;

                    if ((((uintptr_t)src + srcPos) % 16) > 8) {

                        src_v1 = vec_ld(srcPos + j + 16, src);

                    }

                    src_vF = vec_perm(src_v0, src_v1, permS);



                    src_v = // vec_unpackh sign-extends...

                            (vector signed short)(vec_mergeh((vector unsigned char)vzero, src_vF));

                    // loading filter_v0R is useless, it's already done above

                    // vector signed short filter_v0R = vec_ld((i * 2 * filterSize) + j, filter);

                    filter_v1R = vec_ld((i * 2 * filterSize) + (j * 2) + 16, filter);

                    filter_v   = vec_perm(filter_v0R, filter_v1R, permF);



                    val_v = vec_msums(src_v, filter_v, val_v);

                }



                val_s = vec_sums(val_v, vzero);



                vec_st(val_s, 0, tempo);

                dst[i] = FFMIN(tempo[3] >> 7, (1 << 15) - 1);

            }

        }

}
