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-rw-r--r--common/ringbuffer.cpp224
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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 <stdexcept>
+
+#include "almalloc.h"
+
+
+RingBufferPtr RingBuffer::Create(size_t sz, size_t elem_sz, int limit_writes)
+{
+ 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 SIZE_MAX > UINT_MAX
+ power_of_two |= power_of_two>>32;
+#endif
+ }
+ ++power_of_two;
+ if(power_of_two <= sz || power_of_two > std::numeric_limits<size_t>::max()/elem_sz)
+ throw std::overflow_error{"Ring buffer size overflow"};
+
+ const 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, al::byte{});
+}
+
+
+size_t RingBuffer::read(void *dest, size_t cnt) noexcept
+{
+ const size_t free_cnt{readSpace()};
+ if(free_cnt == 0) return 0;
+
+ const size_t to_read{std::min(cnt, free_cnt)};
+ size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
+
+ size_t n1, n2;
+ const 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<al::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;
+}
+
+size_t RingBuffer::peek(void *dest, size_t cnt) const noexcept
+{
+ const size_t free_cnt{readSpace()};
+ if(free_cnt == 0) return 0;
+
+ const size_t to_read{std::min(cnt, free_cnt)};
+ size_t read_ptr{mReadPtr.load(std::memory_order_relaxed) & mSizeMask};
+
+ size_t n1, n2;
+ const 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<al::byte*>(dest));
+ if(n2 > 0)
+ std::copy_n(mBuffer.begin(), n2*mElemSize, outiter);
+ return to_read;
+}
+
+size_t RingBuffer::write(const void *src, size_t cnt) noexcept
+{
+ const size_t free_cnt{writeSpace()};
+ if(free_cnt == 0) return 0;
+
+ const size_t to_write{std::min(cnt, free_cnt)};
+ size_t write_ptr{mWritePtr.load(std::memory_order_relaxed) & mSizeMask};
+
+ size_t n1, n2;
+ const 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 al::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;
+}
+
+
+ll_ringbuffer_data_pair RingBuffer::getReadVector() const noexcept
+{
+ ll_ringbuffer_data_pair ret;
+
+ size_t w{mWritePtr.load(std::memory_order_acquire)};
+ size_t r{mReadPtr.load(std::memory_order_acquire)};
+ w &= mSizeMask;
+ r &= mSizeMask;
+ const size_t free_cnt{(w-r) & mSizeMask};
+
+ const 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 = const_cast<al::byte*>(mBuffer.data() + r*mElemSize);
+ ret.first.len = mSizeMask+1 - r;
+ ret.second.buf = const_cast<al::byte*>(mBuffer.data());
+ ret.second.len = cnt2 & mSizeMask;
+ }
+ else
+ {
+ /* Single part vector: just the rest of the buffer */
+ ret.first.buf = const_cast<al::byte*>(mBuffer.data() + r*mElemSize);
+ ret.first.len = free_cnt;
+ ret.second.buf = nullptr;
+ ret.second.len = 0;
+ }
+
+ return ret;
+}
+
+ll_ringbuffer_data_pair RingBuffer::getWriteVector() const noexcept
+{
+ ll_ringbuffer_data_pair ret;
+
+ size_t w{mWritePtr.load(std::memory_order_acquire)};
+ size_t r{mReadPtr.load(std::memory_order_acquire) + mWriteSize - mSizeMask};
+ w &= mSizeMask;
+ r &= mSizeMask;
+ const size_t free_cnt{(r-w-1) & mSizeMask};
+
+ const 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 = const_cast<al::byte*>(mBuffer.data() + w*mElemSize);
+ ret.first.len = mSizeMask+1 - w;
+ ret.second.buf = const_cast<al::byte*>(mBuffer.data());
+ ret.second.len = cnt2 & mSizeMask;
+ }
+ else
+ {
+ ret.first.buf = const_cast<al::byte*>(mBuffer.data() + w*mElemSize);
+ ret.first.len = free_cnt;
+ ret.second.buf = nullptr;
+ ret.second.len = 0;
+ }
+
+ return ret;
+}
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