src/compiler/BlockLayoutEncoder.cpp

//
// Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#include "compiler/BlockLayoutEncoder.h"
#include "compiler/ShaderVariable.h"
#include "common/mathutil.h"
#include "common/utilities.h"

namespace sh
{

BlockLayoutEncoder::BlockLayoutEncoder(std::vector<BlockMemberInfo> *blockInfoOut)
    : mCurrentOffset(0),
      mBlockInfoOut(blockInfoOut)
{
}

void BlockLayoutEncoder::encodeInterfaceBlockFields(const std::vector<InterfaceBlockField> &fields)
{
    for (unsigned int fieldIndex = 0; fieldIndex < fields.size(); fieldIndex++)
    {
        const InterfaceBlockField &variable = fields[fieldIndex];

        if (variable.fields.size() > 0)
        {
            const unsigned int elementCount = std::max(1u, variable.arraySize);

            for (unsigned int elementIndex = 0; elementIndex < elementCount; elementIndex++)
            {
                enterAggregateType();
                encodeInterfaceBlockFields(variable.fields);
                exitAggregateType();
            }
        }
        else
        {
            encodeInterfaceBlockField(variable);
        }
    }
}

void BlockLayoutEncoder::encodeInterfaceBlockField(const InterfaceBlockField &field)
{
    int arrayStride;
    int matrixStride;

    ASSERT(field.fields.empty());
    getBlockLayoutInfo(field.type, field.arraySize, field.isRowMajorMatrix, &arrayStride, &matrixStride);

    const BlockMemberInfo memberInfo(mCurrentOffset * BytesPerComponent, arrayStride * BytesPerComponent, matrixStride * BytesPerComponent, field.isRowMajorMatrix);

    if (mBlockInfoOut)
    {
        mBlockInfoOut->push_back(memberInfo);
    }

    advanceOffset(field.type, field.arraySize, field.isRowMajorMatrix, arrayStride, matrixStride);
}

void BlockLayoutEncoder::encodeType(GLenum type, unsigned int arraySize, bool isRowMajorMatrix)
{
    int arrayStride;
    int matrixStride;

    getBlockLayoutInfo(type, arraySize, isRowMajorMatrix, &arrayStride, &matrixStride);

    const BlockMemberInfo memberInfo(mCurrentOffset * BytesPerComponent, arrayStride * BytesPerComponent, matrixStride * BytesPerComponent, isRowMajorMatrix);

    if (mBlockInfoOut)
    {
        mBlockInfoOut->push_back(memberInfo);
    }

    advanceOffset(type, arraySize, isRowMajorMatrix, arrayStride, matrixStride);
}

void BlockLayoutEncoder::nextRegister()
{
    mCurrentOffset = rx::roundUp(mCurrentOffset, ComponentsPerRegister);
}

Std140BlockEncoder::Std140BlockEncoder(std::vector<BlockMemberInfo> *blockInfoOut)
    : BlockLayoutEncoder(blockInfoOut)
{
}

void Std140BlockEncoder::enterAggregateType()
{
    nextRegister();
}

void Std140BlockEncoder::exitAggregateType()
{
    nextRegister();
}

void Std140BlockEncoder::getBlockLayoutInfo(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int *arrayStrideOut, int *matrixStrideOut)
{
    // We assume we are only dealing with 4 byte components (no doubles or half-words currently)
    ASSERT(gl::UniformComponentSize(gl::UniformComponentType(type)) == BytesPerComponent);

    int numComponents = gl::UniformComponentCount(type);
    size_t baseAlignment = 0;
    int matrixStride = 0;
    int arrayStride = 0;

    if (gl::IsMatrixType(type))
    {
        baseAlignment = ComponentsPerRegister;
        matrixStride = ComponentsPerRegister;

        if (arraySize > 0)
        {
            const int numRegisters = gl::MatrixRegisterCount(type, isRowMajorMatrix);
            arrayStride = ComponentsPerRegister * numRegisters;
        }
    }
    else if (arraySize > 0)
    {
        baseAlignment = ComponentsPerRegister;
        arrayStride = ComponentsPerRegister;
    }
    else
    {
        const int numComponents = gl::UniformComponentCount(type);
        baseAlignment = (numComponents == 3 ? 4u : static_cast<size_t>(numComponents));
    }

    mCurrentOffset = rx::roundUp(mCurrentOffset, baseAlignment);

    *matrixStrideOut = matrixStride;
    *arrayStrideOut = arrayStride;
}

void Std140BlockEncoder::advanceOffset(GLenum type, unsigned int arraySize, bool isRowMajorMatrix, int arrayStride, int matrixStride)
{
    if (arraySize > 0)
    {
        mCurrentOffset += arrayStride * arraySize;
    }
    else if (gl::IsMatrixType(type))
    {
        ASSERT(matrixStride == ComponentsPerRegister);
        const int numRegisters = gl::MatrixRegisterCount(type, isRowMajorMatrix);
        mCurrentOffset += ComponentsPerRegister * numRegisters;
    }
    else
    {
        mCurrentOffset += gl::UniformComponentCount(type);
    }
}

}