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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gfxAlphaRecovery.h"
#include "gfxImageSurface.h"
#include <emmintrin.h>
// This file should only be compiled on x86 and x64 systems. Additionally,
// you'll need to compile it with -msse2 if you're using GCC on x86.
#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_AMD64))
__declspec(align(16)) static uint32_t greenMaski[] =
{ 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
__declspec(align(16)) static uint32_t alphaMaski[] =
{ 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
static uint32_t greenMaski[] __attribute__ ((aligned (16))) =
{ 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
static uint32_t alphaMaski[] __attribute__ ((aligned (16))) =
{ 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
#elif defined(__SUNPRO_CC) && (defined(__i386) || defined(__x86_64__))
#pragma align 16 (greenMaski, alphaMaski)
static uint32_t greenMaski[] = { 0x0000ff00, 0x0000ff00, 0x0000ff00, 0x0000ff00 };
static uint32_t alphaMaski[] = { 0xff000000, 0xff000000, 0xff000000, 0xff000000 };
#endif
bool
gfxAlphaRecovery::RecoverAlphaSSE2(gfxImageSurface* blackSurf,
const gfxImageSurface* whiteSurf)
{
mozilla::gfx::IntSize size = blackSurf->GetSize();
if (size != whiteSurf->GetSize() ||
(blackSurf->Format() != mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32 &&
blackSurf->Format() != mozilla::gfx::SurfaceFormat::X8R8G8B8_UINT32) ||
(whiteSurf->Format() != mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32 &&
whiteSurf->Format() != mozilla::gfx::SurfaceFormat::X8R8G8B8_UINT32))
return false;
blackSurf->Flush();
whiteSurf->Flush();
unsigned char* blackData = blackSurf->Data();
unsigned char* whiteData = whiteSurf->Data();
if ((NS_PTR_TO_UINT32(blackData) & 0xf) != (NS_PTR_TO_UINT32(whiteData) & 0xf) ||
(blackSurf->Stride() - whiteSurf->Stride()) & 0xf) {
// Cannot keep these in alignment.
return false;
}
__m128i greenMask = _mm_load_si128((__m128i*)greenMaski);
__m128i alphaMask = _mm_load_si128((__m128i*)alphaMaski);
for (int32_t i = 0; i < size.height; ++i) {
int32_t j = 0;
// Loop single pixels until at 4 byte alignment.
while (NS_PTR_TO_UINT32(blackData) & 0xf && j < size.width) {
*((uint32_t*)blackData) =
RecoverPixel(*reinterpret_cast<uint32_t*>(blackData),
*reinterpret_cast<uint32_t*>(whiteData));
blackData += 4;
whiteData += 4;
j++;
}
// This extra loop allows the compiler to do some more clever registry
// management and makes it about 5% faster than with only the 4 pixel
// at a time loop.
for (; j < size.width - 8; j += 8) {
__m128i black1 = _mm_load_si128((__m128i*)blackData);
__m128i white1 = _mm_load_si128((__m128i*)whiteData);
__m128i black2 = _mm_load_si128((__m128i*)(blackData + 16));
__m128i white2 = _mm_load_si128((__m128i*)(whiteData + 16));
// Execute the same instructions as described in RecoverPixel, only
// using an SSE2 packed saturated subtract.
white1 = _mm_subs_epu8(white1, black1);
white2 = _mm_subs_epu8(white2, black2);
white1 = _mm_subs_epu8(greenMask, white1);
white2 = _mm_subs_epu8(greenMask, white2);
// Producing the final black pixel in an XMM register and storing
// that is actually faster than doing a masked store since that
// does an unaligned storage. We have the black pixel in a register
// anyway.
black1 = _mm_andnot_si128(alphaMask, black1);
black2 = _mm_andnot_si128(alphaMask, black2);
white1 = _mm_slli_si128(white1, 2);
white2 = _mm_slli_si128(white2, 2);
white1 = _mm_and_si128(alphaMask, white1);
white2 = _mm_and_si128(alphaMask, white2);
black1 = _mm_or_si128(white1, black1);
black2 = _mm_or_si128(white2, black2);
_mm_store_si128((__m128i*)blackData, black1);
_mm_store_si128((__m128i*)(blackData + 16), black2);
blackData += 32;
whiteData += 32;
}
for (; j < size.width - 4; j += 4) {
__m128i black = _mm_load_si128((__m128i*)blackData);
__m128i white = _mm_load_si128((__m128i*)whiteData);
white = _mm_subs_epu8(white, black);
white = _mm_subs_epu8(greenMask, white);
black = _mm_andnot_si128(alphaMask, black);
white = _mm_slli_si128(white, 2);
white = _mm_and_si128(alphaMask, white);
black = _mm_or_si128(white, black);
_mm_store_si128((__m128i*)blackData, black);
blackData += 16;
whiteData += 16;
}
// Loop single pixels until we're done.
while (j < size.width) {
*((uint32_t*)blackData) =
RecoverPixel(*reinterpret_cast<uint32_t*>(blackData),
*reinterpret_cast<uint32_t*>(whiteData));
blackData += 4;
whiteData += 4;
j++;
}
blackData += blackSurf->Stride() - j * 4;
whiteData += whiteSurf->Stride() - j * 4;
}
blackSurf->MarkDirty();
return true;
}
static int32_t
ByteAlignment(int32_t aAlignToLog2, int32_t aX, int32_t aY=0, int32_t aStride=1)
{
return (aX + aStride * aY) & ((1 << aAlignToLog2) - 1);
}
/*static*/ mozilla::gfx::IntRect
gfxAlphaRecovery::AlignRectForSubimageRecovery(const mozilla::gfx::IntRect& aRect,
gfxImageSurface* aSurface)
{
NS_ASSERTION(mozilla::gfx::SurfaceFormat::A8R8G8B8_UINT32 == aSurface->Format(),
"Thebes grew support for non-ARGB32 COLOR_ALPHA?");
static const int32_t kByteAlignLog2 = GoodAlignmentLog2();
static const int32_t bpp = 4;
static const int32_t pixPerAlign = (1 << kByteAlignLog2) / bpp;
//
// We're going to create a subimage of the surface with size
// <sw,sh> for alpha recovery, and want a SIMD fast-path. The
// rect <x,y, w,h> /needs/ to be redrawn, but it might not be
// properly aligned for SIMD. So we want to find a rect <x',y',
// w',h'> that's a superset of what needs to be redrawn but is
// properly aligned. Proper alignment is
//
// BPP * (x' + y' * sw) \cong 0 (mod ALIGN)
// BPP * w' \cong BPP * sw (mod ALIGN)
//
// (We assume the pixel at surface <0,0> is already ALIGN'd.)
// That rect (obviously) has to fit within the surface bounds, and
// we should also minimize the extra pixels redrawn only for
// alignment's sake. So we also want
//
// minimize <x',y', w',h'>
// 0 <= x' <= x
// 0 <= y' <= y
// w <= w' <= sw
// h <= h' <= sh
//
// This is a messy integer non-linear programming problem, except
// ... we can assume that ALIGN/BPP is a very small constant. So,
// brute force is viable. The algorithm below will find a
// solution if one exists, but isn't guaranteed to find the
// minimum solution. (For SSE2, ALIGN/BPP = 4, so it'll do at
// most 64 iterations below). In what's likely the common case,
// an already-aligned rectangle, it only needs 1 iteration.
//
// Is this alignment worth doing? Recovering alpha will take work
// proportional to w*h (assuming alpha recovery computation isn't
// memory bound). This analysis can lead to O(w+h) extra work
// (with small constants). In exchange, we expect to shave off a
// ALIGN/BPP constant by using SIMD-ized alpha recovery. So as
// w*h diverges from w+h, the win factor approaches ALIGN/BPP. We
// only really care about the w*h >> w+h case anyway; others
// should be fast enough even with the overhead. (Unless the cost
// of repainting the expanded rect is high, but in that case
// SIMD-ized alpha recovery won't make a difference so this code
// shouldn't be called.)
//
mozilla::gfx::IntSize surfaceSize = aSurface->GetSize();
const int32_t stride = bpp * surfaceSize.width;
if (stride != aSurface->Stride()) {
NS_WARNING("Unexpected stride, falling back on slow alpha recovery");
return aRect;
}
const int32_t x = aRect.x, y = aRect.y, w = aRect.width, h = aRect.height;
const int32_t r = x + w;
const int32_t sw = surfaceSize.width;
const int32_t strideAlign = ByteAlignment(kByteAlignLog2, stride);
// The outer two loops below keep the rightmost (|r| above) and
// bottommost pixels in |aRect| fixed wrt <x,y>, to ensure that we
// return only a superset of the original rect. These loops
// search for an aligned top-left pixel by trying to expand <x,y>
// left and up by <dx,dy> pixels, respectively.
//
// Then if a properly-aligned top-left pixel is found, the
// innermost loop tries to find an aligned stride by moving the
// rightmost pixel rightward by dr.
int32_t dx, dy, dr;
for (dy = 0; (dy < pixPerAlign) && (y - dy >= 0); ++dy) {
for (dx = 0; (dx < pixPerAlign) && (x - dx >= 0); ++dx) {
if (0 != ByteAlignment(kByteAlignLog2,
bpp * (x - dx), y - dy, stride)) {
continue;
}
for (dr = 0; (dr < pixPerAlign) && (r + dr <= sw); ++dr) {
if (strideAlign == ByteAlignment(kByteAlignLog2,
bpp * (w + dr + dx))) {
goto FOUND_SOLUTION;
}
}
}
}
// Didn't find a solution.
return aRect;
FOUND_SOLUTION:
mozilla::gfx::IntRect solution = mozilla::gfx::IntRect(x - dx, y - dy, w + dr + dx, h + dy);
MOZ_ASSERT(mozilla::gfx::IntRect(0, 0, sw, surfaceSize.height).Contains(solution),
"'Solution' extends outside surface bounds!");
return solution;
}
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