mirror of
https://github.com/kichikuou/xsystem35-sdl2.git
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100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/*
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* Copyright (C) 2025 <KichikuouChrome@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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include "scheduler.h"
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#include "scenario.h"
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#include "sdl_core.h"
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#include "nact.h"
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#include "hacks.h"
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bool scheduler_yield_requested;
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int scheduler_cmd_count;
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#define BLOOM_FILTER_HASHES 4
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// Knuth's multiplicative hash.
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static uint32_t hash(uint32_t x, int s) {
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return (x * 2654435761ULL) >> s;
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}
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/*
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* System 3.x games are basically driven by busy loops that repeatedly check
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* the state of input devices or timers until their state changes. On modern
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* computers such loops waste power, and in emscripten SDL events are not
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* queued until we call emscripten_sleep(). This function detects such busy
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* loops and schedules a yield.
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*/
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void scheduler_on_event(enum scheduler_event event) {
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static int prev_cmd_count = -1;
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static uint64_t bloom = 0;
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switch (event) {
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case SCHEDULER_EVENT_SLEEP:
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scheduler_yield_requested = false;
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bloom = 0;
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scheduler_cmd_count = 0;
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prev_cmd_count = -1;
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break;
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case SCHEDULER_EVENT_INPUT_CHECK_MISS:
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case SCHEDULER_EVENT_INPUT_CHECK_HIT:
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case SCHEDULER_EVENT_TIMER_CHECK:
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case SCHEDULER_EVENT_AUDIO_CHECK:
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case SCHEDULER_EVENT_VA_STATUS_CHECK:
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// A single Sys3x command may generate multiple scheduler events.
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// Deduplicate them.
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if (prev_cmd_count == scheduler_cmd_count)
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break;
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prev_cmd_count = scheduler_cmd_count;
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if (event == SCHEDULER_EVENT_INPUT_CHECK_HIT) {
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// There are new input events. Let's process them without delay.
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bloom = 0;
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} else {
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uint32_t h1 = hash(sl_getPage(), 7);
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uint32_t h2 = hash(sl_getIndex(), 15);
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uint64_t bits = 0;
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for (int i = 0; i < BLOOM_FILTER_HASHES; i++) {
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uint32_t h = (h1 + (i + 1) * h2) % 64;
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bits |= 1ULL << h;
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}
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if ((bloom & bits) == bits) {
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request_yield();
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bloom = 0;
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} else {
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bloom |= bits;
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}
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}
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break;
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}
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}
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void scheduler_yield(void) {
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switch (game_id) {
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case GAME_AGAKE:
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sdl_sleep(6); // The slot game runs in a 6ms-cycle loop.
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break;
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case GAME_PERSIOM:
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sdl_sleep(10); // The slot game runs in a 10ms-cycle loop.
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break;
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default:
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sdl_wait_vsync();
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break;
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}
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}
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