src/core/SkBlitRow_D32.cpp

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkBlitRow.h"
#include "SkBlitMask.h"
#include "SkColorPriv.h"
#include "SkUtils.h"

#define UNROLL

SkBlitRow::ColorRectProc PlatformColorRectProcFactory();

static void S32_Opaque_BlitRow32(SkPMColor* SK_RESTRICT dst,
                                 const SkPMColor* SK_RESTRICT src,
                                 int count, U8CPU alpha) {
    SkASSERT(255 == alpha);
    sk_memcpy32(dst, src, count);
}

static void S32_Blend_BlitRow32(SkPMColor* SK_RESTRICT dst,
                                const SkPMColor* SK_RESTRICT src,
                                int count, U8CPU alpha) {
    SkASSERT(alpha <= 255);
    if (count > 0) {
        unsigned src_scale = SkAlpha255To256(alpha);
        unsigned dst_scale = 256 - src_scale;

#ifdef UNROLL
        if (count & 1) {
            *dst = SkAlphaMulQ(*(src++), src_scale) + SkAlphaMulQ(*dst, dst_scale);
            dst += 1;
            count -= 1;
        }

        const SkPMColor* SK_RESTRICT srcEnd = src + count;
        while (src != srcEnd) {
            *dst = SkAlphaMulQ(*(src++), src_scale) + SkAlphaMulQ(*dst, dst_scale);
            dst += 1;
            *dst = SkAlphaMulQ(*(src++), src_scale) + SkAlphaMulQ(*dst, dst_scale);
            dst += 1;
        }
#else
        do {
            *dst = SkAlphaMulQ(*src, src_scale) + SkAlphaMulQ(*dst, dst_scale);
            src += 1;
            dst += 1;
        } while (--count > 0);
#endif
    }
}

static void S32A_Opaque_BlitRow32(SkPMColor* SK_RESTRICT dst,
                                  const SkPMColor* SK_RESTRICT src,
                                  int count, U8CPU alpha) {
    SkASSERT(255 == alpha);
    if (count > 0) {
#ifdef UNROLL
        if (count & 1) {
            *dst = SkPMSrcOver(*(src++), *dst);
            dst += 1;
            count -= 1;
        }

        const SkPMColor* SK_RESTRICT srcEnd = src + count;
        while (src != srcEnd) {
            *dst = SkPMSrcOver(*(src++), *dst);
            dst += 1;
            *dst = SkPMSrcOver(*(src++), *dst);
            dst += 1;
        }
#else
        do {
            *dst = SkPMSrcOver(*src, *dst);
            src += 1;
            dst += 1;
        } while (--count > 0);
#endif
    }
}

static void S32A_Blend_BlitRow32(SkPMColor* SK_RESTRICT dst,
                                 const SkPMColor* SK_RESTRICT src,
                                 int count, U8CPU alpha) {
    SkASSERT(alpha <= 255);
    if (count > 0) {
#ifdef UNROLL
        if (count & 1) {
            *dst = SkBlendARGB32(*(src++), *dst, alpha);
            dst += 1;
            count -= 1;
        }

        const SkPMColor* SK_RESTRICT srcEnd = src + count;
        while (src != srcEnd) {
            *dst = SkBlendARGB32(*(src++), *dst, alpha);
            dst += 1;
            *dst = SkBlendARGB32(*(src++), *dst, alpha);
            dst += 1;
        }
#else
        do {
            *dst = SkBlendARGB32(*src, *dst, alpha);
            src += 1;
            dst += 1;
        } while (--count > 0);
#endif
    }
}

///////////////////////////////////////////////////////////////////////////////

static const SkBlitRow::Proc32 gDefault_Procs32[] = {
    S32_Opaque_BlitRow32,
    S32_Blend_BlitRow32,
    S32A_Opaque_BlitRow32,
    S32A_Blend_BlitRow32
};

SkBlitRow::Proc32 SkBlitRow::Factory32(unsigned flags) {
    SkASSERT(flags < SK_ARRAY_COUNT(gDefault_Procs32));
    // just so we don't crash
    flags &= kFlags32_Mask;

    SkBlitRow::Proc32 proc = PlatformProcs32(flags);
    if (NULL == proc) {
        proc = gDefault_Procs32[flags];
    }
    SkASSERT(proc);
    return proc;
}

SkBlitRow::Proc32 SkBlitRow::ColorProcFactory() {
    SkBlitRow::ColorProc proc = PlatformColorProc();
    if (NULL == proc) {
        proc = Color32;
    }
    SkASSERT(proc);
    return proc;
}

void SkBlitRow::Color32(SkPMColor* SK_RESTRICT dst,
                        const SkPMColor* SK_RESTRICT src,
                        int count, SkPMColor color) {
    if (count > 0) {
        if (0 == color) {
            if (src != dst) {
                memcpy(dst, src, count * sizeof(SkPMColor));
            }
            return;
        }
        unsigned colorA = SkGetPackedA32(color);
        if (255 == colorA) {
            sk_memset32(dst, color, count);
        } else {
            unsigned scale = 256 - SkAlpha255To256(colorA);
            do {
                *dst = color + SkAlphaMulQ(*src, scale);
                src += 1;
                dst += 1;
            } while (--count);
        }
    }
}

template <size_t N> void assignLoop(SkPMColor* dst, SkPMColor color) {
    for (size_t i = 0; i < N; ++i) {
        *dst++ = color;
    }
}

static inline void assignLoop(SkPMColor dst[], SkPMColor color, int count) {
    while (count >= 4) {
        *dst++ = color;
        *dst++ = color;
        *dst++ = color;
        *dst++ = color;
        count -= 4;
    }
    if (count >= 2) {
        *dst++ = color;
        *dst++ = color;
        count -= 2;
    }
    if (count > 0) {
        *dst++ = color;
    }
}

void SkBlitRow::ColorRect32(SkPMColor* dst, int width, int height,
                            size_t rowBytes, SkPMColor color) {
    if (width <= 0 || height <= 0 || 0 == color) {
        return;
    }

    // Just made up this value, since I saw it once in a SSE2 file.
    // We should consider writing some tests to find the optimimal break-point
    // (or query the Platform proc?)
    static const int MIN_WIDTH_FOR_SCANLINE_PROC = 32;

    bool isOpaque = (0xFF == SkGetPackedA32(color));

    if (!isOpaque || width >= MIN_WIDTH_FOR_SCANLINE_PROC) {
        SkBlitRow::ColorProc proc = SkBlitRow::ColorProcFactory();
        while (--height >= 0) {
            (*proc)(dst, dst, width, color);
            dst = (SkPMColor*) ((char*)dst + rowBytes);
        }
    } else {
        switch (width) {
            case 1:
                while (--height >= 0) {
                    assignLoop<1>(dst, color);
                    dst = (SkPMColor*) ((char*)dst + rowBytes);
                }
                break;
            case 2:
                while (--height >= 0) {
                    assignLoop<2>(dst, color);
                    dst = (SkPMColor*) ((char*)dst + rowBytes);
                }
                break;
            case 3:
                while (--height >= 0) {
                    assignLoop<3>(dst, color);
                    dst = (SkPMColor*) ((char*)dst + rowBytes);
                }
                break;
            default:
                while (--height >= 0) {
                    assignLoop(dst, color, width);
                    dst = (SkPMColor*) ((char*)dst + rowBytes);
                }
                break;
        }
    }
}

SkBlitRow::ColorRectProc SkBlitRow::ColorRectProcFactory() {
    SkBlitRow::ColorRectProc proc = PlatformColorRectProcFactory();
    if (NULL == proc) {
        proc = ColorRect32;
    }
    SkASSERT(proc);
    return proc;
}