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/**
* OpenAL cross platform audio library
* Copyright (C) 1999-2007 by authors.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include "ringbuffer.h"
#include <algorithm>
#include <climits>
#include <cstdint>
#include <limits>
#include <stdexcept>
#include "almalloc.h"
RingBufferPtr RingBuffer::Create(std::size_t sz, std::size_t elem_sz, int limit_writes)
{
std::size_t power_of_two{0u};
if(sz > 0)
{
power_of_two = sz;
power_of_two |= power_of_two>>1;
power_of_two |= power_of_two>>2;
power_of_two |= power_of_two>>4;
power_of_two |= power_of_two>>8;
power_of_two |= power_of_two>>16;
if constexpr(sizeof(size_t) > sizeof(uint32_t))
power_of_two |= power_of_two>>32;
}
++power_of_two;
if(power_of_two <= sz || power_of_two > std::numeric_limits<std::size_t>::max()/elem_sz)
throw std::overflow_error{"Ring buffer size overflow"};
const std::size_t bufbytes{power_of_two * elem_sz};
RingBufferPtr rb{new(FamCount(bufbytes)) RingBuffer{bufbytes}};
rb->mWriteSize = limit_writes ? sz : (power_of_two-1);
rb->mSizeMask = power_of_two - 1;
rb->mElemSize = elem_sz;
return rb;
}
void RingBuffer::reset() noexcept
{
mWritePtr.store(0, std::memory_order_relaxed);
mReadPtr.store(0, std::memory_order_relaxed);
std::fill_n(mBuffer.begin(), (mSizeMask+1)*mElemSize, std::byte{});
}
std::size_t RingBuffer::read(void *dest, std::size_t cnt) noexcept
{
const std::size_t free_cnt{readSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_read{std::min(cnt, free_cnt)};
std::size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{read_ptr + to_read};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - read_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_read;
n2 = 0;
}
auto outiter = std::copy_n(mBuffer.begin() + read_ptr*mElemSize, n1*mElemSize,
static_cast<std::byte*>(dest));
read_ptr += n1;
if(n2 > 0)
{
std::copy_n(mBuffer.begin(), n2*mElemSize, outiter);
read_ptr += n2;
}
mReadPtr.store(read_ptr, std::memory_order_release);
return to_read;
}
std::size_t RingBuffer::peek(void *dest, std::size_t cnt) const noexcept
{
const std::size_t free_cnt{readSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_read{std::min(cnt, free_cnt)};
std::size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{read_ptr + to_read};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - read_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_read;
n2 = 0;
}
auto outiter = std::copy_n(mBuffer.begin() + read_ptr*mElemSize, n1*mElemSize,
static_cast<std::byte*>(dest));
if(n2 > 0)
std::copy_n(mBuffer.begin(), n2*mElemSize, outiter);
return to_read;
}
std::size_t RingBuffer::write(const void *src, std::size_t cnt) noexcept
{
const std::size_t free_cnt{writeSpace()};
if(free_cnt == 0) return 0;
const std::size_t to_write{std::min(cnt, free_cnt)};
std::size_t write_ptr{mWritePtr.load(std::memory_order_relaxed) & mSizeMask};
std::size_t n1, n2;
const std::size_t cnt2{write_ptr + to_write};
if(cnt2 > mSizeMask+1)
{
n1 = mSizeMask+1 - write_ptr;
n2 = cnt2 & mSizeMask;
}
else
{
n1 = to_write;
n2 = 0;
}
auto srcbytes = static_cast<const std::byte*>(src);
std::copy_n(srcbytes, n1*mElemSize, mBuffer.begin() + write_ptr*mElemSize);
write_ptr += n1;
if(n2 > 0)
{
std::copy_n(srcbytes + n1*mElemSize, n2*mElemSize, mBuffer.begin());
write_ptr += n2;
}
mWritePtr.store(write_ptr, std::memory_order_release);
return to_write;
}
auto RingBuffer::getReadVector() noexcept -> DataPair
{
DataPair ret;
std::size_t w{mWritePtr.load(std::memory_order_acquire)};
std::size_t r{mReadPtr.load(std::memory_order_acquire)};
w &= mSizeMask;
r &= mSizeMask;
const std::size_t free_cnt{(w-r) & mSizeMask};
const std::size_t cnt2{r + free_cnt};
if(cnt2 > mSizeMask+1)
{
/* Two part vector: the rest of the buffer after the current read ptr,
* plus some from the start of the buffer. */
ret.first.buf = mBuffer.data() + r*mElemSize;
ret.first.len = mSizeMask+1 - r;
ret.second.buf = mBuffer.data();
ret.second.len = cnt2 & mSizeMask;
}
else
{
/* Single part vector: just the rest of the buffer */
ret.first.buf = mBuffer.data() + r*mElemSize;
ret.first.len = free_cnt;
ret.second.buf = nullptr;
ret.second.len = 0;
}
return ret;
}
auto RingBuffer::getWriteVector() noexcept -> DataPair
{
DataPair ret;
std::size_t w{mWritePtr.load(std::memory_order_acquire)};
std::size_t r{mReadPtr.load(std::memory_order_acquire) + mWriteSize - mSizeMask};
w &= mSizeMask;
r &= mSizeMask;
const std::size_t free_cnt{(r-w-1) & mSizeMask};
const std::size_t cnt2{w + free_cnt};
if(cnt2 > mSizeMask+1)
{
/* Two part vector: the rest of the buffer after the current write ptr,
* plus some from the start of the buffer. */
ret.first.buf = mBuffer.data() + w*mElemSize;
ret.first.len = mSizeMask+1 - w;
ret.second.buf = mBuffer.data();
ret.second.len = cnt2 & mSizeMask;
}
else
{
ret.first.buf = mBuffer.data() + w*mElemSize;
ret.first.len = free_cnt;
ret.second.buf = nullptr;
ret.second.len = 0;
}
return ret;
}
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