I'm not sure if this test is going to be effective as I don't have hardware to test on at the moment. As noted in the documentation, Windows XP should be the only OS where QPC uses a timer source that is non-monotonic(multi-core with non-syncronized TSC).
200 lines
4.2 KiB
C++
200 lines
4.2 KiB
C++
/*
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* Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "pbd/windows_timer_utils.h"
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#include <windows.h>
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#include <mmsystem.h>
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#include "pbd/compose.h"
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#include "pbd/debug.h"
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#define DEBUG_TIMING(msg) DEBUG_TRACE (PBD::DEBUG::Timing, msg);
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namespace {
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UINT&
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timer_resolution ()
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{
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static UINT timer_res_ms = 0;
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return timer_res_ms;
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}
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}
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namespace PBD {
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namespace MMTIMERS {
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bool
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get_min_resolution (uint32_t& min_resolution_ms)
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{
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TIMECAPS caps;
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if (timeGetDevCaps (&caps, sizeof(TIMECAPS)) != TIMERR_NOERROR) {
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DEBUG_TIMING ("Could not get timer device capabilities.\n");
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return false;
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}
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min_resolution_ms = caps.wPeriodMin;
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return true;
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}
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bool
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set_min_resolution ()
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{
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uint32_t min_resolution = 0;
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if (!get_min_resolution (min_resolution)) {
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return false;
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}
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if (!set_resolution (min_resolution)) {
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return false;
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}
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return true;
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}
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bool
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set_resolution (uint32_t timer_resolution_ms)
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{
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if (timer_resolution() != 0) {
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DEBUG_TIMING(
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"Timer resolution must be reset before setting new resolution.\n");
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}
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if (timeBeginPeriod(timer_resolution_ms) != TIMERR_NOERROR) {
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DEBUG_TIMING(
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string_compose("Could not set timer resolution to %1(ms)\n",
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timer_resolution_ms));
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return false;
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}
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timer_resolution() = timer_resolution_ms;
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DEBUG_TIMING (string_compose ("Multimedia timer resolution set to %1(ms)\n",
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timer_resolution_ms));
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return true;
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}
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bool
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reset_resolution ()
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{
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// You must match calls to timeBegin/EndPeriod with the same resolution
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if (timeEndPeriod(timer_resolution()) != TIMERR_NOERROR) {
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DEBUG_TIMING("Could not reset the Timer resolution.\n");
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return false;
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}
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timer_resolution() = 0;
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return true;
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}
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} // namespace MMTIMERS
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namespace {
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bool&
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qpc_frequency_success ()
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{
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static bool success = false;
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return success;
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}
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LARGE_INTEGER
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qpc_frequency ()
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{
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LARGE_INTEGER freq;
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if (QueryPerformanceFrequency(&freq) == 0) {
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DEBUG_TIMING ("Failed to determine frequency of QPC\n");
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qpc_frequency_success() = false;
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} else {
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qpc_frequency_success() = true;
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}
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return freq;
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}
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LARGE_INTEGER
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qpc_frequency_cached ()
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{
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static LARGE_INTEGER frequency = qpc_frequency ();
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return frequency;
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}
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bool
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test_qpc_validity ()
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{
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int64_t last_timer_val = PBD::QPC::get_microseconds ();
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if (last_timer_val < 0) return false;
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for (int i = 0; i < 100000; ++i) {
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int64_t timer_val = PBD::QPC::get_microseconds ();
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if (timer_val < 0) return false;
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// try and test for non-syncronized TSC(AMD K8/etc)
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if (timer_val < last_timer_val) return false;
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last_timer_val = timer_val;
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}
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return true;
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}
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} // anon namespace
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namespace QPC {
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bool
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check_timer_valid ()
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{
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// setup caching the timer frequency
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qpc_frequency_cached ();
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if (!qpc_frequency_success ()) {
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return false;
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}
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return test_qpc_validity ();
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}
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int64_t
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get_microseconds ()
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{
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LARGE_INTEGER current_val;
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if (qpc_frequency_success()) {
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// MS docs say this will always succeed for systems >= XP but it may
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// not return a monotonic value with non-invariant TSC's etc
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if (QueryPerformanceCounter(¤t_val) != 0) {
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return (int64_t)(((double)current_val.QuadPart) /
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((double)qpc_frequency_cached().QuadPart) * 1000000.0);
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}
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}
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DEBUG_TIMING ("Could not get QPC timer\n");
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return -1;
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}
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} // namespace QPC
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int64_t
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get_microseconds ()
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{
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if (qpc_frequency_success()) {
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return QPC::get_microseconds ();
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}
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// For XP systems that don't support a high-res performance counter
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return g_get_monotonic_time ();
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}
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} // namespace PBD
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