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/**********************************************************************
Audacity: A Digital Audio Editor
FifoBuffer.h
Dmitry Vedenko
**********************************************************************/
#include "FifoBuffer.h"
#include <algorithm>
FifoBuffer::Page::Page(int size)
: Data(size)
{
}
void FifoBuffer::Page::Reset()
{
WritePosition = 0;
ReadPosition = 0;
}
FifoBuffer::FifoBuffer(int pageSize)
: mPageSize { pageSize }
{
}
int64_t FifoBuffer::Write(const void* dataPtr, int64_t size)
{
const int8_t* data = static_cast<const int8_t*>(dataPtr);
auto bytesLeft = size;
while (bytesLeft > 0)
{
if (
mActivePages.empty() ||
mActivePages.back()->WritePosition == mPageSize)
{
if (mFreePages.empty())
{
mAllocatedPages.emplace_back(mPageSize);
mFreePages.push_back(&mAllocatedPages.back());
}
mActivePages.push(mFreePages.back());
mFreePages.pop_back();
}
auto& page = mActivePages.back();
auto toWrite = std::min(
bytesLeft, static_cast<int64_t>(mPageSize - page->WritePosition));
std::copy(data, data + toWrite, page->Data.begin() + page->WritePosition);
page->WritePosition += toWrite;
mAvaliable += toWrite;
data += toWrite;
bytesLeft -= toWrite;
}
return size;
}
int64_t FifoBuffer::Read(void* data, int64_t size)
{
size = std::min(size, mAvaliable);
int8_t* dataPtr = static_cast<int8_t*>(data);
int bytesRead = 0;
while (size > 0)
{
auto& page = mActivePages.front();
auto toRead =
std::min(size, static_cast<int64_t>(mPageSize - page->ReadPosition));
std::copy(
page->Data.begin() + page->ReadPosition,
page->Data.begin() + page->ReadPosition + toRead, dataPtr);
page->ReadPosition += toRead;
mAvaliable -= toRead;
dataPtr += toRead;
size -= toRead;
bytesRead += toRead;
if (page->ReadPosition == mPageSize)
{
page->Reset();
mFreePages.push_back(page);
mActivePages.pop();
}
}
return bytesRead;
}
int64_t FifoBuffer::GetAvailable() const
{
return mAvaliable;
}
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