timer.c

/**
 * Copyright (c) 2020, 2021, 2022 Adrian Siekierka
 *
 * TinyZoo/GB 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 3 of the License, or (at your option)
 * any later version.
 *
 * TinyZoo/GB 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 TinyZoo/GB. If not, see <https://www.gnu.org/licenses/>. 
 *
 * TinyZoo/GB includes code derived from the Reconstruction of ZZT, used under
 * the following license terms:
 *
 * Copyright (c) 2020 Adrian Siekierka
 *
 * Based on a reconstruction of code from ZZT,
 * Copyright 1991 Epic MegaGames, used with permission.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <gbdk/platform.h>
#include "timer.h"

uint16_t dhsecs;

uint16_t timer_hsecs(void) {
	return dhsecs >> 1;
}

bool timer_has_time_elapsed(uint16_t *ctr, uint16_t duration) {
	uint16_t hsecs_diff = (dhsecs >> 1) - *ctr;

	if (hsecs_diff >= duration) {
		*ctr = dhsecs >> 1;
		return true;
	} else {
		return false;
	}
}