/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <private/qdrawhelper_x86_p.h>

#ifdef QT_COMPILER_SUPPORTS_SSSE3

#include <private/qdrawingprimitive_sse2_p.h>

QT_BEGIN_NAMESPACE

inline static void blend_pixel(quint32 &dst, const quint32 src)
{
    if (src >= 0xff000000)
        dst = src;
    else if (src != 0)
        dst = src + BYTE_MUL(dst, qAlpha(~src));
}


/* The instruction palignr uses direct arguments, so we have to generate the code fo the different
   shift (4, 8, 12). Checking the alignment inside the loop is unfortunatelly way too slow.
 */
#define BLENDING_LOOP(palignrOffset, length)\
    for (; x < length-3; x += 4) { \
        const __m128i srcVectorLastLoaded = _mm_load_si128((__m128i *)&src[x - minusOffsetToAlignSrcOn16Bytes + 4]);\
        const __m128i srcVector = _mm_alignr_epi8(srcVectorLastLoaded, srcVectorPrevLoaded, palignrOffset); \
        const __m128i srcVectorAlpha = _mm_and_si128(srcVector, alphaMask); \
        if (_mm_movemask_epi8(_mm_cmpeq_epi32(srcVectorAlpha, alphaMask)) == 0xffff) { \
            _mm_store_si128((__m128i *)&dst[x], srcVector); \
        } else if (_mm_movemask_epi8(_mm_cmpeq_epi32(srcVectorAlpha, nullVector)) != 0xffff) { \
            __m128i alphaChannel = _mm_shuffle_epi8(srcVector, alphaShuffleMask); \
            alphaChannel = _mm_sub_epi16(one, alphaChannel); \
            const __m128i dstVector = _mm_load_si128((__m128i *)&dst[x]); \
            __m128i destMultipliedByOneMinusAlpha; \
            BYTE_MUL_SSE2(destMultipliedByOneMinusAlpha, dstVector, alphaChannel, colorMask, half); \
            const __m128i result = _mm_add_epi8(srcVector, destMultipliedByOneMinusAlpha); \
            _mm_store_si128((__m128i *)&dst[x], result); \
        } \
        srcVectorPrevLoaded = srcVectorLastLoaded;\
    }


// Basically blend src over dst with the const alpha defined as constAlphaVector.
// nullVector, half, one, colorMask are constant across the whole image/texture, and should be defined as:
//const __m128i nullVector = _mm_set1_epi32(0);
//const __m128i half = _mm_set1_epi16(0x80);
//const __m128i one = _mm_set1_epi16(0xff);
//const __m128i colorMask = _mm_set1_epi32(0x00ff00ff);
//const __m128i alphaMask = _mm_set1_epi32(0xff000000);
//
// The computation being done is:
// result = s + d * (1-alpha)
// with shortcuts if fully opaque or fully transparent.
#define BLEND_SOURCE_OVER_ARGB32_SSSE3(dst, src, length, nullVector, half, one, colorMask, alphaMask) { \
    int x = 0; \
\
    /* First, get dst aligned. */ \
    ALIGNMENT_PROLOGUE_16BYTES(dst, x, length) { \
        blend_pixel(dst[x], src[x]); \
    } \
\
    const int minusOffsetToAlignSrcOn16Bytes = (reinterpret_cast<quintptr>(&(src[x])) >> 2) & 0x3;\
\
    if (!minusOffsetToAlignSrcOn16Bytes) {\
        /* src is aligned, usual algorithm but with aligned operations.\
           See the SSE2 version for more documentation on the algorithm itself. */\
        const __m128i alphaShuffleMask = _mm_set_epi8(0xff,15,0xff,15,0xff,11,0xff,11,0xff,7,0xff,7,0xff,3,0xff,3);\
        for (; x < length-3; x += 4) { \
            const __m128i srcVector = _mm_load_si128((__m128i *)&src[x]); \
            const __m128i srcVectorAlpha = _mm_and_si128(srcVector, alphaMask); \
            if (_mm_movemask_epi8(_mm_cmpeq_epi32(srcVectorAlpha, alphaMask)) == 0xffff) { \
                _mm_store_si128((__m128i *)&dst[x], srcVector); \
            } else if (_mm_movemask_epi8(_mm_cmpeq_epi32(srcVectorAlpha, nullVector)) != 0xffff) { \
                __m128i alphaChannel = _mm_shuffle_epi8(srcVector, alphaShuffleMask); \
                alphaChannel = _mm_sub_epi16(one, alphaChannel); \
                const __m128i dstVector = _mm_load_si128((__m128i *)&dst[x]); \
                __m128i destMultipliedByOneMinusAlpha; \
                BYTE_MUL_SSE2(destMultipliedByOneMinusAlpha, dstVector, alphaChannel, colorMask, half); \
                const __m128i result = _mm_add_epi8(srcVector, destMultipliedByOneMinusAlpha); \
                _mm_store_si128((__m128i *)&dst[x], result); \
            } \
        } /* end for() */\
    } else if ((length - x) >= 8) {\
        /* We use two vectors to extract the src: prevLoaded for the first pixels, lastLoaded for the current pixels. */\
        __m128i srcVectorPrevLoaded = _mm_load_si128((__m128i *)&src[x - minusOffsetToAlignSrcOn16Bytes]);\
        const int palignrOffset = minusOffsetToAlignSrcOn16Bytes << 2;\
\
        const __m128i alphaShuffleMask = _mm_set_epi8(0xff,15,0xff,15,0xff,11,0xff,11,0xff,7,0xff,7,0xff,3,0xff,3);\
        switch (palignrOffset) {\
        case 4:\
            BLENDING_LOOP(4, length)\
            break;\
        case 8:\
            BLENDING_LOOP(8, length)\
            break;\
        case 12:\
            BLENDING_LOOP(12, length)\
            break;\
        }\
    }\
    for (; x < length; ++x) \
        blend_pixel(dst[x], src[x]); \
}

void qt_blend_argb32_on_argb32_ssse3(uchar *destPixels, int dbpl,
                                     const uchar *srcPixels, int sbpl,
                                     int w, int h,
                                     int const_alpha)
{
    const quint32 *src = (const quint32 *) srcPixels;
    quint32 *dst = (quint32 *) destPixels;
    if (const_alpha == 256) {
        const __m128i alphaMask = _mm_set1_epi32(0xff000000);
        const __m128i nullVector = _mm_setzero_si128();
        const __m128i half = _mm_set1_epi16(0x80);
        const __m128i one = _mm_set1_epi16(0xff);
        const __m128i colorMask = _mm_set1_epi32(0x00ff00ff);

        for (int y = 0; y < h; ++y) {
            BLEND_SOURCE_OVER_ARGB32_SSSE3(dst, src, w, nullVector, half, one, colorMask, alphaMask);
            dst = (quint32 *)(((uchar *) dst) + dbpl);
            src = (const quint32 *)(((const uchar *) src) + sbpl);
        }
    } else if (const_alpha != 0) {
        // dest = (s + d * sia) * ca + d * cia
        //      = s * ca + d * (sia * ca + cia)
        //      = s * ca + d * (1 - sa*ca)
        const_alpha = (const_alpha * 255) >> 8;
        const __m128i nullVector = _mm_setzero_si128();
        const __m128i half = _mm_set1_epi16(0x80);
        const __m128i one = _mm_set1_epi16(0xff);
        const __m128i colorMask = _mm_set1_epi32(0x00ff00ff);
        const __m128i constAlphaVector = _mm_set1_epi16(const_alpha);
        for (int y = 0; y < h; ++y) {
            BLEND_SOURCE_OVER_ARGB32_WITH_CONST_ALPHA_SSE2(dst, src, w, nullVector, half, one, colorMask, constAlphaVector)
            dst = (quint32 *)(((uchar *) dst) + dbpl);
            src = (const quint32 *)(((const uchar *) src) + sbpl);
        }
    }
}

QT_END_NAMESPACE

#endif // QT_COMPILER_SUPPORTS_SSSE3
