skia/src/src/opts/SkBlitRow_opts_SSE2.cpp

/*
 **
 ** Copyright 2009, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License"); 
 ** you may not use this file except in compliance with the License. 
 ** You may obtain a copy of the License at 
 **
 **     http://www.apache.org/licenses/LICENSE-2.0 
 **
 ** Unless required by applicable law or agreed to in writing, software 
 ** distributed under the License is distributed on an "AS IS" BASIS, 
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 ** See the License for the specific language governing permissions and 
 ** limitations under the License.
 */

#include "SkBlitRow_opts_SSE2.h"
#include "SkColorPriv.h"

#include <emmintrin.h>

/* SSE2 version of S32_Blend_BlitRow32()
 * portable version is in core/SkBlitRow_D32.cpp
 */
void S32_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
                              const SkPMColor* SK_RESTRICT src,
                              int count, U8CPU alpha) {
    SkASSERT(alpha <= 255);
    if (count <= 0) {
        return;
    }

    uint32_t src_scale = SkAlpha255To256(alpha);
    uint32_t dst_scale = 256 - src_scale;

    if (count >= 4) {
        SkASSERT(((size_t)dst & 0x03) == 0);
        while (((size_t)dst & 0x0F) != 0) {
            *dst = SkAlphaMulQ(*src, src_scale) + SkAlphaMulQ(*dst, dst_scale);
            src++;
            dst++;
            count--;
        }

        const __m128i *s = reinterpret_cast<const __m128i*>(src);
        __m128i *d = reinterpret_cast<__m128i*>(dst);
        __m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
        __m128i src_scale_wide = _mm_set1_epi16(src_scale);
        __m128i dst_scale_wide = _mm_set1_epi16(dst_scale);
        while (count >= 4) {
            // Load 4 pixels each of src and dest.
            __m128i src_pixel = _mm_loadu_si128(s);
            __m128i dst_pixel = _mm_load_si128(d);

            // Get red and blue pixels into lower byte of each word.
            __m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
            __m128i src_rb = _mm_and_si128(rb_mask, src_pixel);

            // Get alpha and green into lower byte of each word.
            __m128i dst_ag = _mm_srli_epi16(dst_pixel, 8);
            __m128i src_ag = _mm_srli_epi16(src_pixel, 8);

            // Multiply by scale.
            src_rb = _mm_mullo_epi16(src_rb, src_scale_wide);
            src_ag = _mm_mullo_epi16(src_ag, src_scale_wide);
            dst_rb = _mm_mullo_epi16(dst_rb, dst_scale_wide);
            dst_ag = _mm_mullo_epi16(dst_ag, dst_scale_wide);

            // Divide by 256.
            src_rb = _mm_srli_epi16(src_rb, 8);
            dst_rb = _mm_srli_epi16(dst_rb, 8);
            src_ag = _mm_andnot_si128(rb_mask, src_ag);
            dst_ag = _mm_andnot_si128(rb_mask, dst_ag);

            // Combine back into RGBA.
            src_pixel = _mm_or_si128(src_rb, src_ag);
            dst_pixel = _mm_or_si128(dst_rb, dst_ag);

            // Add result
            __m128i result = _mm_add_epi8(src_pixel, dst_pixel);
            _mm_store_si128(d, result);
            s++;
            d++;
            count -= 4;
        }
        src = reinterpret_cast<const SkPMColor*>(s);
        dst = reinterpret_cast<SkPMColor*>(d);
    }

    while (count > 0) {
        *dst = SkAlphaMulQ(*src, src_scale) + SkAlphaMulQ(*dst, dst_scale);
        src++;
        dst++;
        count--;
    }
}

void S32A_Opaque_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
                                const SkPMColor* SK_RESTRICT src,
                                int count, U8CPU alpha) {
    SkASSERT(alpha == 255);
    if (count <= 0) {
        return;
    }

    if (count >= 4) {
        SkASSERT(((size_t)dst & 0x03) == 0);
        while (((size_t)dst & 0x0F) != 0) {
            *dst = SkPMSrcOver(*src, *dst);
            src++;
            dst++;
            count--;
        }

        const __m128i *s = reinterpret_cast<const __m128i*>(src);
        __m128i *d = reinterpret_cast<__m128i*>(dst);
#ifdef SK_USE_ACCURATE_BLENDING
        __m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
        __m128i c_128 = _mm_set1_epi16(128);  // 8 copies of 128 (16-bit)
        __m128i c_255 = _mm_set1_epi16(255);  // 8 copies of 255 (16-bit)
        while (count >= 4) {
            // Load 4 pixels
            __m128i src_pixel = _mm_loadu_si128(s);
            __m128i dst_pixel = _mm_load_si128(d);

            __m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
            __m128i dst_ag = _mm_andnot_si128(rb_mask, dst_pixel);
            dst_ag = _mm_srli_epi16(dst_ag, 8);
            // Shift alphas down to lower 8 bits of each quad.
            __m128i alpha = _mm_srli_epi32(src_pixel, 24);

            // Copy alpha to upper 3rd byte of each quad
            alpha = _mm_or_si128(alpha, _mm_slli_epi32(alpha, 16));

            // Subtract alphas from 255, to get 0..255
            alpha = _mm_sub_epi16(c_255, alpha);

            // Multiply by red and blue by src alpha.
            dst_rb = _mm_mullo_epi16(dst_rb, alpha);
            // Multiply by alpha and green by src alpha.
            dst_ag = _mm_mullo_epi16(dst_ag, alpha);

            // dst_rb_low = (dst_rb >> 8)
            __m128i dst_rb_low = _mm_srli_epi16(dst_rb, 8);
            __m128i dst_ag_low = _mm_srli_epi16(dst_ag, 8);

            // dst_rb = (dst_rb + dst_rb_low + 128) >> 8
            dst_rb = _mm_add_epi16(dst_rb, dst_rb_low);
            dst_rb = _mm_add_epi16(dst_rb, c_128);
            dst_rb = _mm_srli_epi16(dst_rb, 8);

            // dst_ag = (dst_ag + dst_ag_low + 128) & ag_mask
            dst_ag = _mm_add_epi16(dst_ag, dst_ag_low);
            dst_ag = _mm_add_epi16(dst_ag, c_128);
            dst_ag = _mm_andnot_si128(rb_mask, dst_ag);

            // Combine back into RGBA.
            dst_pixel = _mm_or_si128(dst_rb, dst_ag);

            // Add result
            __m128i result = _mm_add_epi8(src_pixel, dst_pixel);
            _mm_store_si128(d, result);
            s++;
            d++;
            count -= 4;
        }
    #else
        __m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
        __m128i c_256 = _mm_set1_epi16(0x0100);  // 8 copies of 256 (16-bit)
        while (count >= 4) {
            // Load 4 pixels
            __m128i src_pixel = _mm_loadu_si128(s);
            __m128i dst_pixel = _mm_load_si128(d);

            __m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
            __m128i dst_ag = _mm_andnot_si128(rb_mask, dst_pixel);
            dst_ag = _mm_srli_epi16(dst_ag, 8);
            // Shift alphas down to lower 8 bits of each quad.
            __m128i alpha = _mm_srli_epi32(src_pixel, 24);

            // Copy alpha to upper 3rd byte of each quad
            alpha = _mm_or_si128(alpha, _mm_slli_epi32(alpha, 16));

            // Subtract alphas from 256, to get 1..256
            alpha = _mm_sub_epi16(c_256, alpha);

            // Multiply by red and blue by src alpha.
            dst_rb = _mm_mullo_epi16(dst_rb, alpha);
            // Multiply by alpha and green by src alpha.
            dst_ag = _mm_mullo_epi16(dst_ag, alpha);

            // Divide by 256.
            dst_rb = _mm_srli_epi16(dst_rb, 8);

            // Mask out high bits (already in the right place)
            dst_ag = _mm_andnot_si128(rb_mask, dst_ag);

            // Combine back into RGBA.
            dst_pixel = _mm_or_si128(dst_rb, dst_ag);

            // Add result
            __m128i result = _mm_add_epi8(src_pixel, dst_pixel);
            _mm_store_si128(d, result);
            s++;
            d++;
            count -= 4;
        }
#endif
        src = reinterpret_cast<const SkPMColor*>(s);
        dst = reinterpret_cast<SkPMColor*>(d);
    }

    while (count > 0) {
        *dst = SkPMSrcOver(*src, *dst);
        src++;
        dst++;
        count--;
    }
}

void S32A_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
                               const SkPMColor* SK_RESTRICT src,
                               int count, U8CPU alpha) {
    SkASSERT(alpha <= 255);
    if (count <= 0) {
        return;
    }

    if (count >= 4) {
        while (((size_t)dst & 0x0F) != 0) {
            *dst = SkBlendARGB32(*src, *dst, alpha);
            src++;
            dst++;
            count--;
        }

        uint32_t src_scale = SkAlpha255To256(alpha);

        const __m128i *s = reinterpret_cast<const __m128i*>(src);
        __m128i *d = reinterpret_cast<__m128i*>(dst);
        __m128i src_scale_wide = _mm_set1_epi16(src_scale);
        __m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
        __m128i c_256 = _mm_set1_epi16(256);  // 8 copies of 256 (16-bit)
        while (count >= 4) {
            // Load 4 pixels each of src and dest.
            __m128i src_pixel = _mm_loadu_si128(s);
            __m128i dst_pixel = _mm_load_si128(d);

            // Get red and blue pixels into lower byte of each word.
            __m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
            __m128i src_rb = _mm_and_si128(rb_mask, src_pixel);

            // Get alpha and green into lower byte of each word.
            __m128i dst_ag = _mm_srli_epi16(dst_pixel, 8);
            __m128i src_ag = _mm_srli_epi16(src_pixel, 8);

            // Put per-pixel alpha in low byte of each word.
            __m128i dst_alpha = _mm_shufflehi_epi16(src_ag, 0xF5);
            dst_alpha = _mm_shufflelo_epi16(dst_alpha, 0xF5);

            // dst_alpha = dst_alpha * src_scale
            dst_alpha = _mm_mullo_epi16(dst_alpha, src_scale_wide);

            // Divide by 256.
            dst_alpha = _mm_srli_epi16(dst_alpha, 8);

            // Subtract alphas from 256, to get 1..256
            dst_alpha = _mm_sub_epi16(c_256, dst_alpha);

            // Multiply red and blue by dst pixel alpha.
            dst_rb = _mm_mullo_epi16(dst_rb, dst_alpha);
            // Multiply alpha and green by dst pixel alpha.
            dst_ag = _mm_mullo_epi16(dst_ag, dst_alpha);

            // Multiply red and blue by global alpha.
            src_rb = _mm_mullo_epi16(src_rb, src_scale_wide);
            // Multiply alpha and green by global alpha.
            src_ag = _mm_mullo_epi16(src_ag, src_scale_wide);

            // Divide by 256.
            dst_rb = _mm_srli_epi16(dst_rb, 8);
            src_rb = _mm_srli_epi16(src_rb, 8);

            // Mask out low bits (goodies already in the right place; no need to divide)
            dst_ag = _mm_andnot_si128(rb_mask, dst_ag);
            src_ag = _mm_andnot_si128(rb_mask, src_ag);

            // Combine back into RGBA.
            dst_pixel = _mm_or_si128(dst_rb, dst_ag);
            src_pixel = _mm_or_si128(src_rb, src_ag);

            // Add two pixels into result.
            __m128i result = _mm_add_epi8(src_pixel, dst_pixel);
            _mm_store_si128(d, result);
            s++;
            d++;
            count -= 4;
        }
        src = reinterpret_cast<const SkPMColor*>(s);
        dst = reinterpret_cast<SkPMColor*>(d);
    }

    while (count > 0) {
        *dst = SkBlendARGB32(*src, *dst, alpha);
        src++;
        dst++;
        count--;
    }
}