zircon/system/ulib/fidl/builder.cpp

// Copyright 2018 The Fuchsia 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 <lib/fidl/cpp/builder.h>

#include <string.h>

#include <lib/fidl/internal.h>

namespace fidl {

Builder::Builder()
    : capacity_(0u), at_(0u), buffer_(nullptr) {}

Builder::Builder(void* buffer, uint32_t capacity)
    : capacity_(capacity), at_(0u), buffer_(static_cast<uint8_t*>(buffer)) {
}

Builder::~Builder() = default;

Builder::Builder(Builder&& other)
    : capacity_(other.capacity_),
      at_(other.at_),
      buffer_(other.buffer_) {
    other.Reset(nullptr, 0);
}

Builder& Builder::operator=(Builder&& other) {
    if (this != &other) {
        capacity_ = other.capacity_;
        at_ = other.at_;
        buffer_ = other.buffer_;
        other.Reset(nullptr, 0);
    }
    return *this;
}

void* Builder::Allocate(uint32_t size) {
    uint64_t limit = FidlAlign(at_ + size);
    if (limit > capacity_)
        return nullptr;
    uint8_t* result = &buffer_[at_];
    memset(buffer_ + at_, 0, limit - at_);
    at_ = static_cast<uint32_t>(limit);
    return result;
}

BytePart Builder::Finalize() {
    BytePart bytes(buffer_, capacity_, at_);
    capacity_ = 0u;
    at_ = 0u;
    return bytes;
}

void Builder::Reset(void* buffer, uint32_t capacity) {
    buffer_ = static_cast<uint8_t*>(buffer);
    capacity_ = capacity;
    at_ = 0u;
}

} // namespace fidl