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livetrax/libs/pbd/windows_timer_utils.cc
Tim Mayberry f4cb4e479d Rename PBD::QPC::get_timer_valid to check_timer_valid and perform timer test
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).
2015-09-16 11:22:16 +10:00

200 lines
4.2 KiB
C++

/*
* Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "pbd/windows_timer_utils.h"
#include <windows.h>
#include <mmsystem.h>
#include "pbd/compose.h"
#include "pbd/debug.h"
#define DEBUG_TIMING(msg) DEBUG_TRACE (PBD::DEBUG::Timing, msg);
namespace {
UINT&
timer_resolution ()
{
static UINT timer_res_ms = 0;
return timer_res_ms;
}
}
namespace PBD {
namespace MMTIMERS {
bool
get_min_resolution (uint32_t& min_resolution_ms)
{
TIMECAPS caps;
if (timeGetDevCaps (&caps, sizeof(TIMECAPS)) != TIMERR_NOERROR) {
DEBUG_TIMING ("Could not get timer device capabilities.\n");
return false;
}
min_resolution_ms = caps.wPeriodMin;
return true;
}
bool
set_min_resolution ()
{
uint32_t min_resolution = 0;
if (!get_min_resolution (min_resolution)) {
return false;
}
if (!set_resolution (min_resolution)) {
return false;
}
return true;
}
bool
set_resolution (uint32_t timer_resolution_ms)
{
if (timer_resolution() != 0) {
DEBUG_TIMING(
"Timer resolution must be reset before setting new resolution.\n");
}
if (timeBeginPeriod(timer_resolution_ms) != TIMERR_NOERROR) {
DEBUG_TIMING(
string_compose("Could not set timer resolution to %1(ms)\n",
timer_resolution_ms));
return false;
}
timer_resolution() = timer_resolution_ms;
DEBUG_TIMING (string_compose ("Multimedia timer resolution set to %1(ms)\n",
timer_resolution_ms));
return true;
}
bool
reset_resolution ()
{
// You must match calls to timeBegin/EndPeriod with the same resolution
if (timeEndPeriod(timer_resolution()) != TIMERR_NOERROR) {
DEBUG_TIMING("Could not reset the Timer resolution.\n");
return false;
}
timer_resolution() = 0;
return true;
}
} // namespace MMTIMERS
namespace {
bool&
qpc_frequency_success ()
{
static bool success = false;
return success;
}
LARGE_INTEGER
qpc_frequency ()
{
LARGE_INTEGER freq;
if (QueryPerformanceFrequency(&freq) == 0) {
DEBUG_TIMING ("Failed to determine frequency of QPC\n");
qpc_frequency_success() = false;
} else {
qpc_frequency_success() = true;
}
return freq;
}
LARGE_INTEGER
qpc_frequency_cached ()
{
static LARGE_INTEGER frequency = qpc_frequency ();
return frequency;
}
bool
test_qpc_validity ()
{
int64_t last_timer_val = PBD::QPC::get_microseconds ();
if (last_timer_val < 0) return false;
for (int i = 0; i < 100000; ++i) {
int64_t timer_val = PBD::QPC::get_microseconds ();
if (timer_val < 0) return false;
// try and test for non-syncronized TSC(AMD K8/etc)
if (timer_val < last_timer_val) return false;
last_timer_val = timer_val;
}
return true;
}
} // anon namespace
namespace QPC {
bool
check_timer_valid ()
{
// setup caching the timer frequency
qpc_frequency_cached ();
if (!qpc_frequency_success ()) {
return false;
}
return test_qpc_validity ();
}
int64_t
get_microseconds ()
{
LARGE_INTEGER current_val;
if (qpc_frequency_success()) {
// MS docs say this will always succeed for systems >= XP but it may
// not return a monotonic value with non-invariant TSC's etc
if (QueryPerformanceCounter(&current_val) != 0) {
return (int64_t)(((double)current_val.QuadPart) /
((double)qpc_frequency_cached().QuadPart) * 1000000.0);
}
}
DEBUG_TIMING ("Could not get QPC timer\n");
return -1;
}
} // namespace QPC
int64_t
get_microseconds ()
{
if (qpc_frequency_success()) {
return QPC::get_microseconds ();
}
// For XP systems that don't support a high-res performance counter
return g_get_monotonic_time ();
}
} // namespace PBD