// Copyright 2020 The Dawn & Tint Authors
//
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// modification, are permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
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// 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.
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// 3. Neither the name of the copyright holder nor the names of its
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#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/439062058): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "src/tint/lang/spirv/writer/common/binary_writer.h"

#include <cstring>
#include <string>

#include "src/tint/utils/memory/bitcast.h"

namespace tint::spirv::writer {
namespace {

const uint32_t kGeneratorId = 23u << 16;

}  // namespace

BinaryWriter::BinaryWriter() = default;

BinaryWriter::~BinaryWriter() = default;

void BinaryWriter::WriteModule(const Module& module) {
    out_.reserve(module.TotalSize());
    module.Iterate([this](const Instruction& inst) { this->ProcessInstruction(inst); });
}

void BinaryWriter::WriteInstruction(const Instruction& inst) {
    ProcessInstruction(inst);
}

void BinaryWriter::WriteHeader(uint32_t bound, uint32_t version, uint32_t spirv_version) {
    out_.push_back(spv::MagicNumber);
    out_.push_back(spirv_version);
    out_.push_back(kGeneratorId | version);
    out_.push_back(bound);
    out_.push_back(0);
}

void BinaryWriter::ProcessInstruction(const Instruction& inst) {
    TINT_ASSERT(inst.WordLength() < 65536);
    out_.push_back(inst.WordLength() << 16 | static_cast<uint32_t>(inst.Opcode()));
    for (const auto& op : inst.Operands()) {
        ProcessOp(op);
    }
}

void BinaryWriter::ProcessOp(const Operand& op) {
    if (auto* i = std::get_if<uint32_t>(&op)) {
        out_.push_back(*i);
        return;
    }
    if (auto* f = std::get_if<float>(&op)) {
        out_.push_back(tint::Bitcast<uint32_t>(*f));
        return;
    }
    if (auto* str = std::get_if<std::string>(&op)) {
        auto idx = out_.size();
        out_.resize(out_.size() + OperandLength(op), 0);
        memcpy(&out_[idx], str->c_str(), str->size() + 1);
        return;
    }
}

}  // namespace tint::spirv::writer
