c6db88b0cf
- Bump revision of protobuf lib - Remove -Wextra for arm64 gcc targets (warnings in stlport) - Add MemoryBarrier implementation in single_rw_fifo.cc. - [pending 15619004]: Bump revision of /deps/tools/android to get md5sum_bin for arm64. BUG=chromium:354405,chromium:354539 R=andrew@webrtc.org, fischman@webrtc.org Review URL: https://webrtc-codereview.appspot.com/15629004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@6330 4adac7df-926f-26a2-2b94-8c16560cd09d
101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
/*
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* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/modules/audio_device/android/single_rw_fifo.h"
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#include <assert.h>
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static int UpdatePos(int pos, int capacity) {
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return (pos + 1) % capacity;
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}
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namespace webrtc {
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namespace subtle {
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#if defined(__aarch64__)
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// From http://http://src.chromium.org/viewvc/chrome/trunk/src/base/atomicops_internals_arm64_gcc.h
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inline void MemoryBarrier() {
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__asm__ __volatile__ ("dmb ish" ::: "memory");
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}
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#elif defined(__ARMEL__)
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// From http://src.chromium.org/viewvc/chrome/trunk/src/base/atomicops_internals_arm_gcc.h
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inline void MemoryBarrier() {
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// Note: This is a function call, which is also an implicit compiler barrier.
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typedef void (*KernelMemoryBarrierFunc)();
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((KernelMemoryBarrierFunc)0xffff0fa0)();
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}
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#elif defined(__x86_64__) || defined (__i386__)
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// From http://src.chromium.org/viewvc/chrome/trunk/src/base/atomicops_internals_x86_gcc.h
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// mfence exists on x64 and x86 platforms containing SSE2.
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// x86 platforms that don't have SSE2 will crash with SIGILL.
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// If this code needs to run on such platforms in the future,
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// add runtime CPU detection here.
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inline void MemoryBarrier() {
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__asm__ __volatile__("mfence" : : : "memory");
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}
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#else
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#error Add an implementation of MemoryBarrier() for this platform!
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#endif
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} // namespace subtle
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SingleRwFifo::SingleRwFifo(int capacity)
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: capacity_(capacity),
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size_(0),
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read_pos_(0),
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write_pos_(0) {
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queue_.reset(new int8_t*[capacity_]);
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}
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SingleRwFifo::~SingleRwFifo() {
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}
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void SingleRwFifo::Push(int8_t* mem) {
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assert(mem);
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// Ensure that there is space for the new data in the FIFO.
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// Note there is only one writer meaning that the other thread is guaranteed
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// only to decrease the size.
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const int free_slots = capacity() - size();
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if (free_slots <= 0) {
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// Size can be queried outside of the Push function. The caller is assumed
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// to ensure that Push will be successful before calling it.
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assert(false);
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return;
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}
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queue_[write_pos_] = mem;
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// Memory barrier ensures that |size_| is updated after the size has changed.
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subtle::MemoryBarrier();
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++size_;
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write_pos_ = UpdatePos(write_pos_, capacity());
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}
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int8_t* SingleRwFifo::Pop() {
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int8_t* ret_val = NULL;
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if (size() <= 0) {
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// Size can be queried outside of the Pop function. The caller is assumed
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// to ensure that Pop will be successfull before calling it.
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assert(false);
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return ret_val;
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}
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ret_val = queue_[read_pos_];
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// Memory barrier ensures that |size_| is updated after the size has changed.
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subtle::MemoryBarrier();
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--size_;
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read_pos_ = UpdatePos(read_pos_, capacity());
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return ret_val;
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}
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} // namespace webrtc
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