// Copyright 2019 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "dawn/wire/WireDeserializeAllocator.h"

#include <algorithm>

namespace dawn::wire {
WireDeserializeAllocator::WireDeserializeAllocator() {
    Reset();
}

WireDeserializeAllocator::~WireDeserializeAllocator() {
    Reset();
}

void* WireDeserializeAllocator::GetSpace(size_t size) {
    // Return space in the current buffer if possible first.
    if (mRemainingSize >= size) {
        char* buffer = mCurrentBuffer;
        mCurrentBuffer += size;
        mRemainingSize -= size;
        return buffer;
    }

    // Otherwise allocate a new buffer and try again.
    size_t allocationSize = std::max(size, size_t(2048));
    char* allocation = static_cast<char*>(malloc(allocationSize));
    if (allocation == nullptr) {
        return nullptr;
    }

    mAllocations.push_back(allocation);
    mCurrentBuffer = allocation;
    mRemainingSize = allocationSize;
    return GetSpace(size);
}

void WireDeserializeAllocator::Reset() {
    for (auto* allocation : mAllocations) {
        free(allocation);
    }
    mAllocations.clear();

    // The initial buffer is the inline buffer so that some allocations can be skipped
    mCurrentBuffer = mStaticBuffer;
    mRemainingSize = sizeof(mStaticBuffer);
}
}  // namespace dawn::wire