/*
 * Copyright (C) 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2010 Mozilla Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WEBGLTEXELCONVERSIONS_H_
#define WEBGLTEXELCONVERSIONS_H_

#ifdef __SUNPRO_CC
#define __restrict
#endif

#include "WebGLTypes.h"
#include <stdint.h>
#include "mozilla/Attributes.h"

namespace mozilla {

// single precision float
// seeeeeeeemmmmmmmmmmmmmmmmmmmmmmm

// half precision float
// seeeeemmmmmmmmmm

// IEEE 16bits floating point:
const uint16_t kFloat16Value_Zero     = 0x0000; // = 0000000000000000b
const uint16_t kFloat16Value_One      = 0x3C00; // = 0011110000000000b
const uint16_t kFloat16Value_Infinity = 0x7C00; // = 0111110000000000b
const uint16_t kFloat16Value_NaN      = 0x7FFF; // = 011111yyyyyyyyyyb (nonzero y)

MOZ_ALWAYS_INLINE uint16_t
packToFloat16(float v)
{
    union {
        float f32Value;
        uint32_t f32Bits;
    };

    f32Value = v;

    // pull the sign from v into f16bits
    uint16_t f16Bits = uint16_t(f32Bits >> 16) & 0x8000;
    const uint32_t mantissa = f32Bits & 0x7FFFFF;
    const uint32_t exp = (f32Bits >> 23) & 0xFF;

    // Adapted from: OpenGL ES 2.0 Programming Guide Appx.
    // Converting Float to Half-Float
    // 143 = 255 - 127 + 15
    //     = sp_max - sp_bias + hp_bias
    if (exp >= 143) {
        if (mantissa && exp == 0xFF) {
            // Single precision was NaN
            return f16Bits | kFloat16Value_NaN;
        } else {
            // Outside range, store as infinity
            return f16Bits | kFloat16Value_Infinity;
        }
    }

    // too small, try to make a denormalized number
    // 112 = 255 - 127 - (15 + 1)
    //     = sp_max - sp_bias - (hp_bias + 1)
    if (exp <= 112) {
        return f16Bits | uint16_t(mantissa >> (14 + 112 - exp));
    }

    f16Bits |= uint16_t(exp - 112) << 10;
    f16Bits |= uint16_t(mantissa >> 13) & 0x03FF;

    return f16Bits;
}

MOZ_ALWAYS_INLINE float
unpackFromFloat16(uint16_t v)
{
    union {
        float f32Value;
        uint32_t f32Bits;
    };

    // grab sign bit
    f32Bits = uint32_t(v & 0x8000) << 16;
    uint16_t exp = (v >> 10) & 0x001F;
    uint16_t mantissa = v & 0x03FF;

    if (exp) {
        // Handle denormalized numbers
        // Adapted from: OpenGL ES 2.0 Programming Guide Appx.
        // Converting Float to Half-Float
        if (mantissa) {
            exp = 112; // See packToFloat16
            mantissa <<= 1;
            // For every leading zero, decrement the exponent
            // and shift the mantissa to the left
            while ((mantissa & (1 << 10)) == 0) {
                mantissa <<= 1;
                --exp;
            }
            mantissa &= 0x03FF;

            f32Bits |= (exp << 23) | (mantissa << 13);

            // Denormalized number
            return f32Value;
        }

        // +/- zero
        return f32Value;
    }

    if (exp == 0x001F) {
        if (v & 0x03FF) {
            // this is a NaN
            f32Bits |= 0x7FFFFFFF;
        } else {
            // this is -inf or +inf
            f32Bits |= 0x7F800000;
        }
        return f32Value;
    }

    f32Bits |= uint32_t(exp + (-15 + 127)) << 23;
    f32Bits |= uint32_t(v & 0x03FF) << 13;

    return f32Value;
}

MOZ_BEGIN_ENUM_CLASS(WebGLTexelPremultiplicationOp, int)
    None,
    Premultiply,
    Unpremultiply
MOZ_END_ENUM_CLASS(WebGLTexelPremultiplicationOp)

namespace WebGLTexelConversions {

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct IsFloatFormat
{
    static const bool Value =
        Format == WebGLTexelFormat::RGBA32F ||
        Format == WebGLTexelFormat::RGB32F ||
        Format == WebGLTexelFormat::RA32F ||
        Format == WebGLTexelFormat::R32F ||
        Format == WebGLTexelFormat::A32F;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct IsHalfFloatFormat
{
    static const bool Value =
        Format == WebGLTexelFormat::RGBA16F ||
        Format == WebGLTexelFormat::RGB16F ||
        Format == WebGLTexelFormat::RA16F ||
        Format == WebGLTexelFormat::R16F ||
        Format == WebGLTexelFormat::A16F;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct Is16bppFormat
{
    static const bool Value =
        Format == WebGLTexelFormat::RGBA4444 ||
        Format == WebGLTexelFormat::RGBA5551 ||
        Format == WebGLTexelFormat::RGB565;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format,
         bool IsFloat = IsFloatFormat<Format>::Value,
         bool Is16bpp = Is16bppFormat<Format>::Value,
         bool IsHalfFloat = IsHalfFloatFormat<Format>::Value>
struct DataTypeForFormat
{
    typedef uint8_t Type;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct DataTypeForFormat<Format, true, false, false>
{
    typedef float Type;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct DataTypeForFormat<Format, false, true, false>
{
    typedef uint16_t Type;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct DataTypeForFormat<Format, false, false, true>
{
    typedef uint16_t Type;
};

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
struct IntermediateFormat
{
    static const MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Value
        = IsFloatFormat<Format>::Value
          ? WebGLTexelFormat::RGBA32F
          : IsHalfFloatFormat<Format>::Value ? WebGLTexelFormat::RGBA16F
                                             : WebGLTexelFormat::RGBA8;
};

inline GLenum
GLFormatForTexelFormat(WebGLTexelFormat format) {
    switch (format) {
        case WebGLTexelFormat::R8:          return LOCAL_GL_LUMINANCE;
        case WebGLTexelFormat::A8:          return LOCAL_GL_ALPHA;
        case WebGLTexelFormat::RA8:         return LOCAL_GL_LUMINANCE_ALPHA;
        case WebGLTexelFormat::RGBA5551:    return LOCAL_GL_RGBA;
        case WebGLTexelFormat::RGBA4444:    return LOCAL_GL_RGBA;
        case WebGLTexelFormat::RGB565:      return LOCAL_GL_RGB;
        case WebGLTexelFormat::D16:         return LOCAL_GL_DEPTH_COMPONENT;
        case WebGLTexelFormat::RGB8:        return LOCAL_GL_RGB;
        case WebGLTexelFormat::RGBA8:       return LOCAL_GL_RGBA;
        case WebGLTexelFormat::BGRA8:       return LOCAL_GL_BGRA;
        case WebGLTexelFormat::BGRX8:       return LOCAL_GL_BGR;
        case WebGLTexelFormat::R32F:        return LOCAL_GL_LUMINANCE;
        case WebGLTexelFormat::A32F:        return LOCAL_GL_ALPHA;
        case WebGLTexelFormat::D32:         return LOCAL_GL_DEPTH_COMPONENT;
        case WebGLTexelFormat::D24S8:       return LOCAL_GL_DEPTH_STENCIL;
        case WebGLTexelFormat::RA32F:       return LOCAL_GL_LUMINANCE_ALPHA;
        case WebGLTexelFormat::RGB32F:      return LOCAL_GL_RGB;
        case WebGLTexelFormat::RGBA32F:     return LOCAL_GL_RGBA;
        case WebGLTexelFormat::R16F:        return LOCAL_GL_LUMINANCE;
        case WebGLTexelFormat::A16F:        return LOCAL_GL_ALPHA;
        case WebGLTexelFormat::RA16F:       return LOCAL_GL_LUMINANCE_ALPHA;
        case WebGLTexelFormat::RGB16F:      return LOCAL_GL_RGB;
        case WebGLTexelFormat::RGBA16F:     return LOCAL_GL_RGBA;
        default:
            MOZ_CRASH("Unknown texel format. Coding mistake?");
            return LOCAL_GL_INVALID_ENUM;
    }
}

inline size_t TexelBytesForFormat(WebGLTexelFormat format) {
    switch (format) {
        case WebGLTexelFormat::R8:
        case WebGLTexelFormat::A8:
            return 1;
        case WebGLTexelFormat::RA8:
        case WebGLTexelFormat::RGBA5551:
        case WebGLTexelFormat::RGBA4444:
        case WebGLTexelFormat::RGB565:
        case WebGLTexelFormat::R16F:
        case WebGLTexelFormat::A16F:
        case WebGLTexelFormat::D16:
            return 2;
        case WebGLTexelFormat::RGB8:
            return 3;
        case WebGLTexelFormat::RGBA8:
        case WebGLTexelFormat::BGRA8:
        case WebGLTexelFormat::BGRX8:
        case WebGLTexelFormat::R32F:
        case WebGLTexelFormat::A32F:
        case WebGLTexelFormat::D32:
        case WebGLTexelFormat::D24S8:
        case WebGLTexelFormat::RA16F:
            return 4;
        case WebGLTexelFormat::RGB16F:
            return 6;
        case WebGLTexelFormat::RGBA16F:
        case WebGLTexelFormat::RA32F:
            return 8;
        case WebGLTexelFormat::RGB32F:
            return 12;
        case WebGLTexelFormat::RGBA32F:
            return 16;
        default:
            MOZ_ASSERT(false, "Unknown texel format. Coding mistake?");
            return 0;
    }
}

MOZ_ALWAYS_INLINE bool HasAlpha(WebGLTexelFormat format) {
    return format == WebGLTexelFormat::A8 ||
           format == WebGLTexelFormat::A16F ||
           format == WebGLTexelFormat::A32F ||
           format == WebGLTexelFormat::RA8 ||
           format == WebGLTexelFormat::RA16F ||
           format == WebGLTexelFormat::RA32F ||
           format == WebGLTexelFormat::RGBA8 ||
           format == WebGLTexelFormat::BGRA8 ||
           format == WebGLTexelFormat::RGBA16F ||
           format == WebGLTexelFormat::RGBA32F ||
           format == WebGLTexelFormat::RGBA4444 ||
           format == WebGLTexelFormat::RGBA5551;
}

MOZ_ALWAYS_INLINE bool HasColor(WebGLTexelFormat format) {
    return format == WebGLTexelFormat::R8 ||
           format == WebGLTexelFormat::R16F ||
           format == WebGLTexelFormat::R32F ||
           format == WebGLTexelFormat::RA8 ||
           format == WebGLTexelFormat::RA16F ||
           format == WebGLTexelFormat::RA32F ||
           format == WebGLTexelFormat::RGB8 ||
           format == WebGLTexelFormat::BGRX8 ||
           format == WebGLTexelFormat::RGB565 ||
           format == WebGLTexelFormat::RGB16F ||
           format == WebGLTexelFormat::RGB32F ||
           format == WebGLTexelFormat::RGBA8 ||
           format == WebGLTexelFormat::BGRA8 ||
           format == WebGLTexelFormat::RGBA16F ||
           format == WebGLTexelFormat::RGBA32F ||
           format == WebGLTexelFormat::RGBA4444 ||
           format == WebGLTexelFormat::RGBA5551;
}


/****** BEGIN CODE SHARED WITH WEBKIT ******/

// the pack/unpack functions here are originally from this file:
//   http://trac.webkit.org/browser/trunk/WebCore/platform/graphics/GraphicsContext3D.cpp

//----------------------------------------------------------------------
// Pixel unpacking routines.

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format, typename SrcType, typename DstType>
MOZ_ALWAYS_INLINE void
unpack(const SrcType* __restrict src,
       DstType* __restrict dst)
{
    MOZ_ASSERT(false, "Unimplemented texture format conversion");
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGBA8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGB8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = 0xFF;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::BGRA8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[2];
    dst[1] = src[1];
    dst[2] = src[0];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::BGRX8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[2];
    dst[1] = src[1];
    dst[2] = src[0];
    dst[3] = 0xFF;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGBA5551, uint16_t, uint8_t>(const uint16_t* __restrict src, uint8_t* __restrict dst)
{
    uint16_t packedValue = src[0];
    uint8_t r = (packedValue >> 11) & 0x1F;
    uint8_t g = (packedValue >> 6) & 0x1F;
    uint8_t b = (packedValue >> 1) & 0x1F;
    dst[0] = (r << 3) | (r & 0x7);
    dst[1] = (g << 3) | (g & 0x7);
    dst[2] = (b << 3) | (b & 0x7);
    dst[3] = (packedValue & 0x1) ? 0xFF : 0;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGBA4444, uint16_t, uint8_t>(const uint16_t* __restrict src, uint8_t* __restrict dst)
{
    uint16_t packedValue = src[0];
    uint8_t r = (packedValue >> 12) & 0x0F;
    uint8_t g = (packedValue >> 8) & 0x0F;
    uint8_t b = (packedValue >> 4) & 0x0F;
    uint8_t a = packedValue & 0x0F;
    dst[0] = (r << 4) | r;
    dst[1] = (g << 4) | g;
    dst[2] = (b << 4) | b;
    dst[3] = (a << 4) | a;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGB565, uint16_t, uint8_t>(const uint16_t* __restrict src, uint8_t* __restrict dst)
{
    uint16_t packedValue = src[0];
    uint8_t r = (packedValue >> 11) & 0x1F;
    uint8_t g = (packedValue >> 5) & 0x3F;
    uint8_t b = packedValue & 0x1F;
    dst[0] = (r << 3) | (r & 0x7);
    dst[1] = (g << 2) | (g & 0x3);
    dst[2] = (b << 3) | (b & 0x7);
    dst[3] = 0xFF;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::R8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = 0xFF;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RA8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::A8, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = 0;
    dst[1] = 0;
    dst[2] = 0;
    dst[3] = src[0];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGBA32F, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGB32F, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = 1.0f;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::R32F, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = 1.0f;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RA32F, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::A32F, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = 0;
    dst[1] = 0;
    dst[2] = 0;
    dst[3] = src[0];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGBA16F, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RGB16F, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = kFloat16Value_One;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::R16F, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = kFloat16Value_One;
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::RA16F, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[0];
    dst[2] = src[0];
    dst[3] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
unpack<WebGLTexelFormat::A16F, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = kFloat16Value_Zero;
    dst[1] = kFloat16Value_Zero;
    dst[2] = kFloat16Value_Zero;
    dst[3] = src[0];
}

//----------------------------------------------------------------------
// Pixel packing routines.
//

template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format,
         MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelPremultiplicationOp) PremultiplicationOp,
         typename SrcType,
         typename DstType>
MOZ_ALWAYS_INLINE void
pack(const SrcType* __restrict src,
     DstType* __restrict dst)
{
    MOZ_ASSERT(false, "Unimplemented texture format conversion");
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A8, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A8, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R8, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    dst[0] = srcR;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R8, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    dst[0] = srcR;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA8, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    dst[0] = srcR;
    dst[1] = src[3];
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA8, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    dst[0] = srcR;
    dst[1] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB8, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    dst[0] = srcR;
    dst[1] = srcG;
    dst[2] = srcB;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB8, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    dst[0] = srcR;
    dst[1] = srcG;
    dst[2] = srcB;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA8, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    dst[0] = srcR;
    dst[1] = srcG;
    dst[2] = srcB;
    dst[3] = src[3];
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA8, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    dst[0] = srcR;
    dst[1] = srcG;
    dst[2] = srcB;
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA4444, WebGLTexelPremultiplicationOp::None, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    *dst = ( ((src[0] & 0xF0) << 8)
           | ((src[1] & 0xF0) << 4)
           | (src[2] & 0xF0)
           | (src[3] >> 4) );
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA4444, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF0) << 8)
           | ((srcG & 0xF0) << 4)
           | (srcB & 0xF0)
           | (src[3] >> 4));
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA4444, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF0) << 8)
           | ((srcG & 0xF0) << 4)
           | (srcB & 0xF0)
           | (src[3] >> 4));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA5551, WebGLTexelPremultiplicationOp::None, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    *dst = ( ((src[0] & 0xF8) << 8)
           | ((src[1] & 0xF8) << 3)
           | ((src[2] & 0xF8) >> 2)
           | (src[3] >> 7));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA5551, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF8) << 8)
           | ((srcG & 0xF8) << 3)
           | ((srcB & 0xF8) >> 2)
           | (src[3] >> 7));
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA5551, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF8) << 8)
           | ((srcG & 0xF8) << 3)
           | ((srcB & 0xF8) >> 2)
           | (src[3] >> 7));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB565, WebGLTexelPremultiplicationOp::None, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    *dst = ( ((src[0] & 0xF8) << 8)
           | ((src[1] & 0xFC) << 3)
           | ((src[2] & 0xF8) >> 3));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB565, WebGLTexelPremultiplicationOp::Premultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] / 255.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF8) << 8)
           | ((srcG & 0xFC) << 3)
           | ((srcB & 0xF8) >> 3));
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB565, WebGLTexelPremultiplicationOp::Unpremultiply, uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = src[3] ? 255.0f / src[3] : 1.0f;
    uint8_t srcR = static_cast<uint8_t>(src[0] * scaleFactor);
    uint8_t srcG = static_cast<uint8_t>(src[1] * scaleFactor);
    uint8_t srcB = static_cast<uint8_t>(src[2] * scaleFactor);
    *dst = ( ((srcR & 0xF8) << 8)
           | ((srcG & 0xFC) << 3)
           | ((srcB & 0xF8) >> 3));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB32F, WebGLTexelPremultiplicationOp::Premultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3];
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
    dst[2] = src[2] * scaleFactor;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA32F, WebGLTexelPremultiplicationOp::Premultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3];
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
    dst[2] = src[2] * scaleFactor;
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A32F, WebGLTexelPremultiplicationOp::Premultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R32F, WebGLTexelPremultiplicationOp::Premultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3];
    dst[0] = src[0] * scaleFactor;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA32F, WebGLTexelPremultiplicationOp::Premultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3];
    dst[0] = src[0] * scaleFactor;
    dst[1] = scaleFactor;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB16F, WebGLTexelPremultiplicationOp::Premultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = unpackFromFloat16(src[3]);
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
    dst[1] = packToFloat16(unpackFromFloat16(src[1]) * scaleFactor);
    dst[2] = packToFloat16(unpackFromFloat16(src[2]) * scaleFactor);
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGBA16F, WebGLTexelPremultiplicationOp::Premultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = unpackFromFloat16(src[3]);
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
    dst[1] = packToFloat16(unpackFromFloat16(src[1]) * scaleFactor);
    dst[2] = packToFloat16(unpackFromFloat16(src[2]) * scaleFactor);
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::A16F, WebGLTexelPremultiplicationOp::Premultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::R16F, WebGLTexelPremultiplicationOp::Premultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = unpackFromFloat16(src[3]);
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA16F, WebGLTexelPremultiplicationOp::Premultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float scaleFactor = unpackFromFloat16(src[3]);
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
    dst[1] = scaleFactor;
}

/****** END CODE SHARED WITH WEBKIT ******/

template<typename SrcType, typename DstType> MOZ_ALWAYS_INLINE void
convertType(const SrcType* __restrict src, DstType* __restrict dst)
{
    MOZ_ASSERT(false, "Unimplemented texture format conversion");
}

template<> MOZ_ALWAYS_INLINE void
convertType<uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
convertType<uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
convertType<float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
    dst[2] = src[2];
    dst[3] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
convertType<uint8_t, float>(const uint8_t* __restrict src, float* __restrict dst)
{
    const float scaleFactor = 1.f / 255.0f;
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
    dst[2] = src[2] * scaleFactor;
    dst[3] = src[3] * scaleFactor;
}

template<> MOZ_ALWAYS_INLINE void
convertType<uint8_t, uint16_t>(const uint8_t* __restrict src, uint16_t* __restrict dst)
{
    const float scaleFactor = 1.f / 255.0f;
    dst[0] = packToFloat16(src[0] * scaleFactor);
    dst[1] = packToFloat16(src[1] * scaleFactor);
    dst[2] = packToFloat16(src[2] * scaleFactor);
    dst[3] = packToFloat16(src[3] * scaleFactor);
}

} // end namespace WebGLTexelConversions

} // end namespace mozilla

#endif // WEBGLTEXELCONVERSIONS_H_