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/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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 <android/util/EncodedBuffer.h>
#include <stdlib.h>
namespace android {
namespace util {
const size_t BUFFER_SIZE = 8 * 1024; // 8 KB
EncodedBuffer::Pointer::Pointer() : Pointer(BUFFER_SIZE)
{
}
EncodedBuffer::Pointer::Pointer(size_t chunkSize)
:mIndex(0),
mOffset(0)
{
mChunkSize = chunkSize == 0 ? BUFFER_SIZE : chunkSize;
}
size_t
EncodedBuffer::Pointer::pos() const
{
return mIndex * mChunkSize + mOffset;
}
size_t
EncodedBuffer::Pointer::index() const
{
return mIndex;
}
size_t
EncodedBuffer::Pointer::offset() const
{
return mOffset;
}
void
EncodedBuffer::Pointer::move(size_t amt)
{
size_t newOffset = mOffset + amt;
mIndex += newOffset / mChunkSize;
mOffset = newOffset % mChunkSize;
}
void
EncodedBuffer::Pointer::rewind()
{
mIndex = 0;
mOffset = 0;
}
EncodedBuffer::Pointer
EncodedBuffer::Pointer::copy() const
{
Pointer p = Pointer(mChunkSize);
p.mIndex = mIndex;
p.mOffset = mOffset;
return p;
}
// ===========================================================
EncodedBuffer::EncodedBuffer() : EncodedBuffer(0)
{
}
EncodedBuffer::EncodedBuffer(size_t chunkSize)
:mBuffers()
{
mChunkSize = chunkSize == 0 ? BUFFER_SIZE : chunkSize;
mWp = Pointer(mChunkSize);
}
EncodedBuffer::~EncodedBuffer()
{
for (size_t i=0; i<mBuffers.size(); i++) {
uint8_t* buf = mBuffers[i];
free(buf);
}
}
inline uint8_t*
EncodedBuffer::at(const Pointer& p) const
{
return mBuffers[p.index()] + p.offset();
}
/******************************** Write APIs ************************************************/
size_t
EncodedBuffer::size() const
{
return mWp.pos();
}
EncodedBuffer::Pointer*
EncodedBuffer::wp()
{
return &mWp;
}
uint8_t*
EncodedBuffer::writeBuffer()
{
// This prevents write pointer move too fast than allocating the buffer.
if (mWp.index() > mBuffers.size()) return NULL;
uint8_t* buf = NULL;
if (mWp.index() == mBuffers.size()) {
buf = (uint8_t*)malloc(mChunkSize);
if (buf == NULL) return NULL; // This indicates NO_MEMORY
mBuffers.push_back(buf);
}
return at(mWp);
}
size_t
EncodedBuffer::currentToWrite()
{
return mChunkSize - mWp.offset();
}
size_t
EncodedBuffer::writeRawVarint(uint32_t val)
{
size_t size = 0;
while (true) {
size++;
if ((val & ~0x7F) == 0) {
*writeBuffer() = (uint8_t) val;
mWp.move();
return size;
} else {
*writeBuffer() = (uint8_t)((val & 0x7F) | 0x80);
mWp.move();
val >>= 7;
}
}
}
size_t
EncodedBuffer::writeHeader(uint32_t fieldId, uint8_t wireType)
{
return writeRawVarint((fieldId << 3) | wireType);
}
/********************************* Read APIs ************************************************/
EncodedBuffer::iterator
EncodedBuffer::begin() const
{
return EncodedBuffer::iterator(*this);
}
EncodedBuffer::iterator::iterator(const EncodedBuffer& buffer)
:mData(buffer),
mRp(buffer.mChunkSize)
{
}
size_t
EncodedBuffer::iterator::size() const
{
return mData.size();
}
size_t
EncodedBuffer::iterator::bytesRead() const
{
return mRp.pos();
}
EncodedBuffer::Pointer*
EncodedBuffer::iterator::rp()
{
return &mRp;
}
uint8_t const*
EncodedBuffer::iterator::readBuffer()
{
return hasNext() ? const_cast<uint8_t const*>(mData.at(mRp)) : NULL;
}
size_t
EncodedBuffer::iterator::currentToRead()
{
return (mData.mWp.index() > mRp.index()) ?
mData.mChunkSize - mRp.offset() :
mData.mWp.offset() - mRp.offset();
}
bool
EncodedBuffer::iterator::hasNext()
{
return mRp.pos() < mData.mWp.pos();
}
uint8_t
EncodedBuffer::iterator::next()
{
uint8_t res = *(mData.at(mRp));
mRp.move();
return res;
}
uint32_t
EncodedBuffer::iterator::readRawVarint()
{
uint32_t val = 0, shift = 0;
while (true) {
uint8_t byte = next();
val += (byte & 0x7F) << shift;
if ((byte & 0x80) == 0) break;
shift += 7;
}
return val;
}
} // util
} // android
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