Chris Robinson
f23ff0394d
Certain backends don't need a buffer size to be a strict multiple of the period count, which allows a little more flexibility. The period/update size simply acts as the minimum request, which helps control CPU load by determining how often parameter and other pre-mixing updates are processed.
59 lines
1.5 KiB
C++
59 lines
1.5 KiB
C++
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#include "config.h"
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#include <cstdlib>
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#include <thread>
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#include "alMain.h"
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#include "alu.h"
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#include "backends/base.h"
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ClockLatency GetClockLatency(ALCdevice *device)
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{
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BackendBase *backend{device->Backend.get()};
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ClockLatency ret{backend->getClockLatency()};
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ret.Latency += device->FixedLatency;
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return ret;
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}
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/* BackendBase method implementations. */
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BackendBase::BackendBase(ALCdevice *device) noexcept : mDevice{device}
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{ }
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BackendBase::~BackendBase() = default;
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ALCboolean BackendBase::reset()
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{ return ALC_FALSE; }
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ALCenum BackendBase::captureSamples(void* UNUSED(buffer), ALCuint UNUSED(samples))
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{ return ALC_INVALID_DEVICE; }
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ALCuint BackendBase::availableSamples()
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{ return 0; }
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ClockLatency BackendBase::getClockLatency()
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{
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ClockLatency ret;
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ALuint refcount;
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do {
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while(((refcount=mDevice->MixCount.load(std::memory_order_acquire))&1))
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std::this_thread::yield();
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ret.ClockTime = GetDeviceClockTime(mDevice);
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std::atomic_thread_fence(std::memory_order_acquire);
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} while(refcount != mDevice->MixCount.load(std::memory_order_relaxed));
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/* NOTE: The device will generally have about all but one periods filled at
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* any given time during playback. Without a more accurate measurement from
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* the output, this is an okay approximation.
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*/
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ret.Latency = std::chrono::seconds{maxi(mDevice->BufferSize-mDevice->UpdateSize, 0)};
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ret.Latency /= mDevice->Frequency;
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return ret;
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}
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