1 files changed, 251 insertions, 0 deletions
diff --git a/alc/ringbuffer.cpp b/alc/ringbuffer.cpp
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+++ b/alc/ringbuffer.cpp
@@ -0,0 +1,251 @@
+/**
+ * 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 <stdexcept>
+
+#include "almalloc.h"
+
+
+RingBufferPtr CreateRingBuffer(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::readSpace() const noexcept
+{
+    size_t w = mWritePtr.load(std::memory_order_acquire);
+    size_t r = mReadPtr.load(std::memory_order_acquire);
+    return (w-r) & mSizeMask;
+}
+
+size_t RingBuffer::writeSpace() const noexcept
+{
+    size_t w = mWritePtr.load(std::memory_order_acquire);
+    size_t r = mReadPtr.load(std::memory_order_acquire) + mWriteSize - mSizeMask;
+    return (r-w-1) & mSizeMask;
+}
+
+
+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;
+}
+
+
+void RingBuffer::readAdvance(size_t cnt) noexcept
+{
+    mReadPtr.fetch_add(cnt, std::memory_order_acq_rel);
+}
+
+void RingBuffer::writeAdvance(size_t cnt) noexcept
+{
+    mWritePtr.fetch_add(cnt, std::memory_order_acq_rel);
+}
+
+
+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;
+}