91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
/*
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* This software is licensed under the terms of the MIT License.
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* See COPYING for further information.
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* ---
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* Copyright (c) 2011-2019, Lukas Weber <laochailan@web.de>.
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* Copyright (c) 2012-2019, Andrei Alexeyev <akari@taisei-project.org>.
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*/
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#include "taisei.h"
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#include "util.h"
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#include "hirestime.h"
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#include "thread.h"
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static bool use_hires;
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static hrtime_t time_current;
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static hrtime_t time_offset;
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static uint64_t prev_hires_time;
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static uint64_t prev_hires_freq;
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static uint64_t fast_path_mul;
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INLINE void set_freq(uint64_t freq) {
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prev_hires_freq = freq;
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lldiv_t d = lldiv(HRTIME_RESOLUTION, freq);
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fast_path_mul = d.quot * (d.rem == 0);
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}
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static void time_update(void) {
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bool retry;
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do {
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retry = false;
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uint64_t freq = SDL_GetPerformanceFrequency();
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uint64_t cntr = SDL_GetPerformanceCounter();
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if(freq != prev_hires_freq) {
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log_debug("High resolution timer frequency changed: was %"PRIu64", now %"PRIu64". Saved time offset: %"PRIuTIME"", prev_hires_freq, freq, time_offset);
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time_offset = time_current;
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set_freq(freq);
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prev_hires_time = SDL_GetPerformanceCounter();
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retry = true;
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continue;
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}
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hrtime_t time_new;
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if(fast_path_mul) {
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time_new = time_offset + (cntr - prev_hires_time) * fast_path_mul;
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} else {
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time_new = time_offset + umuldiv64(cntr - prev_hires_time, HRTIME_RESOLUTION, freq);
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}
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if(time_new < time_current) {
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log_warn("BUG: time went backwards. Was %"PRIuTIME", now %"PRIuTIME". Possible cause: your OS sucks spherical objects. Attempting to correct this...", time_current, time_new);
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time_offset = time_current;
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time_current = 0;
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prev_hires_time = SDL_GetPerformanceCounter();
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retry = true;
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} else {
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time_current = time_new;
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}
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} while(retry);
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}
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void time_init(void) {
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use_hires = env_get("TAISEI_HIRES_TIMER", 1);
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if(use_hires) {
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log_info("Using the system high resolution timer");
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prev_hires_time = SDL_GetPerformanceCounter();
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set_freq(SDL_GetPerformanceFrequency());
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} else {
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log_info("Not using the system high resolution timer: disabled by environment");
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return;
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}
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}
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void time_shutdown(void) {
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}
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hrtime_t time_get(void) {
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if(use_hires) {
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assert(thread_current_is_main());
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time_update();
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return time_current;
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}
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return SDL_GetTicks() * (HRTIME_RESOLUTION / 1000);
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}
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