//
// Copyright 2018 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.
//
// AtomicCounterFunctionHLSL: Class for writing implementation of atomic counter functions into HLSL
// output.
//

#include "compiler/translator/AtomicCounterFunctionHLSL.h"

#include "compiler/translator/Common.h"
#include "compiler/translator/ImmutableStringBuilder.h"
#include "compiler/translator/InfoSink.h"
#include "compiler/translator/IntermNode.h"
#include "nb/cpp14oncpp11.h"

namespace sh
{

namespace
{
CONSTEXPR ImmutableString kAtomicCounter("atomicCounter");
CONSTEXPR ImmutableString kAtomicCounterIncrement("atomicCounterIncrement");
CONSTEXPR ImmutableString kAtomicCounterDecrement("atomicCounterDecrement");
CONSTEXPR ImmutableString kAtomicCounterBaseName("_acbase_");
}  // namespace

AtomicCounterFunctionHLSL::AtomicCounterFunctionHLSL(bool forceResolution)
    : mForceResolution(forceResolution)
{}

ImmutableString AtomicCounterFunctionHLSL::useAtomicCounterFunction(const ImmutableString &name)
{
    // The largest string that will be create created is "_acbase_increment" or "_acbase_decrement"
    ImmutableStringBuilder hlslFunctionNameSB(kAtomicCounterBaseName.length() +
                                              strlen("increment"));
    hlslFunctionNameSB << kAtomicCounterBaseName;

    AtomicCounterFunction atomicMethod;
    if (kAtomicCounter == name)
    {
        atomicMethod = AtomicCounterFunction::LOAD;
        hlslFunctionNameSB << "load";
    }
    else if (kAtomicCounterIncrement == name)
    {
        atomicMethod = AtomicCounterFunction::INCREMENT;
        hlslFunctionNameSB << "increment";
    }
    else if (kAtomicCounterDecrement == name)
    {
        atomicMethod = AtomicCounterFunction::DECREMENT;
        hlslFunctionNameSB << "decrement";
    }
    else
    {
        atomicMethod = AtomicCounterFunction::INVALID;
        UNREACHABLE();
    }

    ImmutableString hlslFunctionName(hlslFunctionNameSB);
    mAtomicCounterFunctions[hlslFunctionName] = atomicMethod;

    return hlslFunctionName;
}

void AtomicCounterFunctionHLSL::atomicCounterFunctionHeader(TInfoSinkBase &out)
{
    for (auto &atomicFunction : mAtomicCounterFunctions)
    {
        out << "uint " << atomicFunction.first
            << "(in RWByteAddressBuffer counter, int address)\n"
               "{\n"
               "    uint ret;\n";

        switch (atomicFunction.second)
        {
            case AtomicCounterFunction::INCREMENT:
                out << "    counter.InterlockedAdd(address, 1u, ret);\n";
                break;
            case AtomicCounterFunction::DECREMENT:
                out << "    counter.InterlockedAdd(address, 0u - 1u, ret);\n"
                       "    ret -= 1u;\n";  // atomicCounterDecrement is a post-decrement op
                break;
            case AtomicCounterFunction::LOAD:
                out << "    ret = counter.Load(address);\n";
                break;
            default:
                UNREACHABLE();
                break;
        }

        if (mForceResolution && atomicFunction.second != AtomicCounterFunction::LOAD)
        {
            out << "    if (ret == 0) {\n"
                   "        ret = 0 - ret;\n"
                   "    }\n";
        }

        out << "    return ret;\n"
               "}\n\n";
    }
}

ImmutableString getAtomicCounterNameForBinding(int binding)
{
    std::stringstream counterName = sh::InitializeStream<std::stringstream>();
    counterName << kAtomicCounterBaseName << binding;
    return ImmutableString(counterName.str());
}

}  // namespace sh