palemoon-dev/platform/dom/canvas/WebGLTexelConversions.h

/*
 * 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"
#include "mozilla/Casting.h"

namespace mozilla {

bool ConvertImage(size_t width, size_t height,
                  const void* srcBegin, size_t srcStride, gl::OriginPos srcOrigin,
                  WebGLTexelFormat srcFormat, bool srcPremultiplied,
                  void* dstBegin, size_t dstStride, gl::OriginPos dstOrigin,
                  WebGLTexelFormat dstFormat, bool dstPremultiplied,
                  bool* out_wasTrivial);

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

// 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;
}

// These routines come from angle/common/mathutil.h
// They are copied here to remove the dependency on ANGLE headers
// included from mathutil.h
MOZ_ALWAYS_INLINE uint16_t
packToFloat11(float fp32)
{
    const unsigned int float32MantissaMask = 0x7FFFFF;
    const unsigned int float32ExponentMask = 0x7F800000;
    const unsigned int float32SignMask = 0x80000000;
    const unsigned int float32ValueMask = ~float32SignMask;
    const unsigned int float32ExponentFirstBit = 23;
    const unsigned int float32ExponentBias = 127;

    const unsigned short float11Max = 0x7BF;
    const unsigned short float11MantissaMask = 0x3F;
    const unsigned short float11ExponentMask = 0x7C0;
    const unsigned short float11BitMask = 0x7FF;
    const unsigned int float11ExponentBias = 14;

    const unsigned int float32Maxfloat11 = 0x477E0000;
    const unsigned int float32Minfloat11 = 0x38800000;

    const unsigned int float32Bits = BitwiseCast<unsigned int>(fp32);
    const bool float32Sign = (float32Bits & float32SignMask) == float32SignMask;

    unsigned int float32Val = float32Bits & float32ValueMask;

    if ((float32Val & float32ExponentMask) == float32ExponentMask)
    {
        // INF or NAN
        if ((float32Val & float32MantissaMask) != 0)
        {
            return float11ExponentMask | (((float32Val >> 17) | (float32Val >> 11) | (float32Val >> 6) | (float32Val)) & float11MantissaMask);
        }
        else if (float32Sign)
        {
            // -INF is clamped to 0 since float11 is positive only
            return 0;
        }
        else
        {
            return float11ExponentMask;
        }
    }
    else if (float32Sign)
    {
        // float11 is positive only, so clamp to zero
        return 0;
    }
    else if (float32Val > float32Maxfloat11)
    {
        // The number is too large to be represented as a float11, set to max
        return float11Max;
    }
    else
    {
        if (float32Val < float32Minfloat11)
        {
            // The number is too small to be represented as a normalized float11
            // Convert it to a denormalized value.
            const unsigned int shift = (float32ExponentBias - float11ExponentBias) - (float32Val >> float32ExponentFirstBit);
            float32Val = ((1 << float32ExponentFirstBit) | (float32Val & float32MantissaMask)) >> shift;
        }
        else
        {
            // Rebias the exponent to represent the value as a normalized float11
            float32Val += 0xC8000000;
        }

        return ((float32Val + 0xFFFF + ((float32Val >> 17) & 1)) >> 17) & float11BitMask;
    }
}

MOZ_ALWAYS_INLINE uint16_t
packToFloat10(float fp32)
{
    const unsigned int float32MantissaMask = 0x7FFFFF;
    const unsigned int float32ExponentMask = 0x7F800000;
    const unsigned int float32SignMask = 0x80000000;
    const unsigned int float32ValueMask = ~float32SignMask;
    const unsigned int float32ExponentFirstBit = 23;
    const unsigned int float32ExponentBias = 127;

    const unsigned short float10Max = 0x3DF;
    const unsigned short float10MantissaMask = 0x1F;
    const unsigned short float10ExponentMask = 0x3E0;
    const unsigned short float10BitMask = 0x3FF;
    const unsigned int float10ExponentBias = 14;

    const unsigned int float32Maxfloat10 = 0x477C0000;
    const unsigned int float32Minfloat10 = 0x38800000;

    const unsigned int float32Bits = BitwiseCast<unsigned int>(fp32);
    const bool float32Sign = (float32Bits & float32SignMask) == float32SignMask;

    unsigned int float32Val = float32Bits & float32ValueMask;

    if ((float32Val & float32ExponentMask) == float32ExponentMask)
    {
        // INF or NAN
        if ((float32Val & float32MantissaMask) != 0)
        {
            return float10ExponentMask | (((float32Val >> 18) | (float32Val >> 13) | (float32Val >> 3) | (float32Val)) & float10MantissaMask);
        }
        else if (float32Sign)
        {
            // -INF is clamped to 0 since float11 is positive only
            return 0;
        }
        else
        {
            return float10ExponentMask;
        }
    }
    else if (float32Sign)
    {
        // float10 is positive only, so clamp to zero
        return 0;
    }
    else if (float32Val > float32Maxfloat10)
    {
        // The number is too large to be represented as a float11, set to max
        return float10Max;
    }
    else
    {
        if (float32Val < float32Minfloat10)
        {
            // The number is too small to be represented as a normalized float11
            // Convert it to a denormalized value.
            const unsigned int shift = (float32ExponentBias - float10ExponentBias) - (float32Val >> float32ExponentFirstBit);
            float32Val = ((1 << float32ExponentFirstBit) | (float32Val & float32MantissaMask)) >> shift;
        }
        else
        {
            // Rebias the exponent to represent the value as a normalized float11
            float32Val += 0xC8000000;
        }

        return ((float32Val + 0x1FFFF + ((float32Val >> 18) & 1)) >> 18) & float10BitMask;
    }
}


enum class WebGLTexelPremultiplicationOp : int {
    None,
    Premultiply,
    Unpremultiply
};

namespace WebGLTexelConversions {

template<WebGLTexelFormat Format>
struct IsFloatFormat
{
    static const bool Value =
        Format == WebGLTexelFormat::A32F         ||
        Format == WebGLTexelFormat::R32F         ||
        Format == WebGLTexelFormat::RA32F        ||
        Format == WebGLTexelFormat::RG32F        ||
        Format == WebGLTexelFormat::RGB11F11F10F ||
        Format == WebGLTexelFormat::RGB32F       ||
        Format == WebGLTexelFormat::RGBA32F;
};

template<WebGLTexelFormat Format>
struct IsHalfFloatFormat
{
    static const bool Value =
        Format == WebGLTexelFormat::A16F   ||
        Format == WebGLTexelFormat::R16F   ||
        Format == WebGLTexelFormat::RA16F  ||
        Format == WebGLTexelFormat::RG16F  ||
        Format == WebGLTexelFormat::RGB16F ||
        Format == WebGLTexelFormat::RGBA16F;
};

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

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

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

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

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

template<>
struct DataTypeForFormat<WebGLTexelFormat::RGB11F11F10F, true, false, false>
{
    typedef uint32_t Type;
};

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

inline size_t TexelBytesForFormat(WebGLTexelFormat format) {
    switch (format) {
    case WebGLTexelFormat::A8:
    case WebGLTexelFormat::R8:
        return 1;
    case WebGLTexelFormat::A16F:
    case WebGLTexelFormat::R16F:
    case WebGLTexelFormat::RA8:
    case WebGLTexelFormat::RG8:
    case WebGLTexelFormat::RGB565:
    case WebGLTexelFormat::RGBA4444:
    case WebGLTexelFormat::RGBA5551:
        return 2;
    case WebGLTexelFormat::RGB8:
        return 3;
    case WebGLTexelFormat::A32F:
    case WebGLTexelFormat::R32F:
    case WebGLTexelFormat::RA16F:
    case WebGLTexelFormat::RG16F:
    case WebGLTexelFormat::RGB11F11F10F:
    case WebGLTexelFormat::RGBA8:
    case WebGLTexelFormat::BGRX8:
    case WebGLTexelFormat::BGRA8:
        return 4;
    case WebGLTexelFormat::RGB16F:
        return 6;
    case WebGLTexelFormat::RA32F:
    case WebGLTexelFormat::RG32F:
    case WebGLTexelFormat::RGBA16F:
        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::RGBA4444 ||
            format == WebGLTexelFormat::RGBA5551 ||
            format == WebGLTexelFormat::RGBA8    ||
            format == WebGLTexelFormat::RGBA16F  ||
            format == WebGLTexelFormat::RGBA32F  ||
            format == WebGLTexelFormat::BGRA8);
}

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::RG8      ||
            format == WebGLTexelFormat::RG16F    ||
            format == WebGLTexelFormat::RG32F    ||
            format == WebGLTexelFormat::RGB565   ||
            format == WebGLTexelFormat::RGB8     ||
            format == WebGLTexelFormat::RGB11F11F10F ||
            format == WebGLTexelFormat::RGB16F   ||
            format == WebGLTexelFormat::RGB32F   ||
            format == WebGLTexelFormat::RGBA4444 ||
            format == WebGLTexelFormat::RGBA5551 ||
            format == WebGLTexelFormat::RGBA8    ||
            format == WebGLTexelFormat::RGBA16F  ||
            format == WebGLTexelFormat::RGBA32F  ||
            format == WebGLTexelFormat::BGRX8    ||
            format == WebGLTexelFormat::BGRA8);
}

/****** 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<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");
}

////////////////////////////////////////////////////////////////////////////////
// 1-channel formats
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::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];
}

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::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::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::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;
}

////////////////////////////////////////////////////////////////////////////////
// 2-channel formats
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::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::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];
}

////////////////////////////////////////////////////////////////////////////////
// 3-channel formats
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::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::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::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;
}

////////////////////////////////////////////////////////////////////////////////
// 4-channel formats
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::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::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::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::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];
}

////////////////////////////////////////////////////////////////////////////////
// DOM element formats
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::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];
}

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

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

////////////////////////////////////////////////////////////////////////////////
// 1-channel formats
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::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::A16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = 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::A32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __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::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::R16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float unpackedAlpha = unpackFromFloat16(src[3]);
    float scaleFactor = unpackedAlpha ? 1.0f / unpackedAlpha : 1.0f;
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
}

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::R32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = src[0] * scaleFactor;
}

////////////////////////////////////////////////////////////////////////////////
// 2-channel formats
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::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] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float unpackedAlpha = unpackFromFloat16(src[3]);
    float scaleFactor = unpackedAlpha ? 1.0f / unpackedAlpha : 1.0f;
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
    dst[1] = src[3];
}

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] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RA32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[3];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG8, WebGLTexelPremultiplicationOp::None, uint8_t, uint8_t>(const uint8_t* __restrict src, uint8_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG8, 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);
    dst[0] = srcR;
    dst[1] = srcG;
}

// FIXME: this routine is lossy and must be removed.
template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG8, 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);
    dst[0] = srcR;
    dst[1] = srcG;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG16F, WebGLTexelPremultiplicationOp::None, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG16F, 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);
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float unpackedAlpha = unpackFromFloat16(src[3]);
    float scaleFactor = unpackedAlpha ? 1.0f / unpackedAlpha : 1.0f;
    dst[0] = packToFloat16(unpackFromFloat16(src[0]) * scaleFactor);
    dst[1] = packToFloat16(unpackFromFloat16(src[1]) * scaleFactor);
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG32F, WebGLTexelPremultiplicationOp::None, float, float>(const float* __restrict src, float* __restrict dst)
{
    dst[0] = src[0];
    dst[1] = src[1];
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG32F, 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;
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RG32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
}

////////////////////////////////////////////////////////////////////////////////
// 3-channel formats
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::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::RGB11F11F10F, WebGLTexelPremultiplicationOp::None, float, uint32_t>(const float* __restrict src, uint32_t* __restrict dst)
{
    dst[0] = ((packToFloat11(src[0]) <<  0) |
              (packToFloat11(src[1]) << 11) |
              (packToFloat10(src[2]) << 22));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB11F11F10F, WebGLTexelPremultiplicationOp::Premultiply, float, uint32_t>(const float* __restrict src, uint32_t* __restrict dst)
{
    float scaleFactor = src[3];
    dst[0] = ((packToFloat11(src[0] * scaleFactor) <<  0) |
              (packToFloat11(src[1] * scaleFactor) << 11) |
              (packToFloat10(src[2] * scaleFactor) << 22));
}

template<> MOZ_ALWAYS_INLINE void
pack<WebGLTexelFormat::RGB11F11F10F, WebGLTexelPremultiplicationOp::Unpremultiply, float, uint32_t>(const float* __restrict src, uint32_t* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = ((packToFloat11(src[0] * scaleFactor) <<  0) |
              (packToFloat11(src[1] * scaleFactor) << 11) |
              (packToFloat10(src[2] * scaleFactor) << 22));
}

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::RGB16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float unpackedAlpha = unpackFromFloat16(src[3]);
    float scaleFactor = unpackedAlpha ? 1.0f / unpackedAlpha : 1.0f;
    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::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::RGB32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
    dst[2] = src[2] * scaleFactor;
}

////////////////////////////////////////////////////////////////////////////////
// 4-channel formats
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::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::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::RGBA16F, WebGLTexelPremultiplicationOp::Unpremultiply, uint16_t, uint16_t>(const uint16_t* __restrict src, uint16_t* __restrict dst)
{
    float unpackedAlpha = unpackFromFloat16(src[3]);
    float scaleFactor = unpackedAlpha ? 1.0f / unpackedAlpha : 1.0f;
    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::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::RGBA32F, WebGLTexelPremultiplicationOp::Unpremultiply, float, float>(const float* __restrict src, float* __restrict dst)
{
    float scaleFactor = src[3] ? 1.0f / src[3] : 1.0f;
    dst[0] = src[0] * scaleFactor;
    dst[1] = src[1] * scaleFactor;
    dst[2] = src[2] * scaleFactor;
    dst[3] = src[3];
}

/****** 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_