/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>,
 * Copyright (C) 2010 Piotr Esden-Tempski <piotr@esden.net>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <libopencm3/stm32/f1/rcc.h>
#include <libopencm3/stm32/f1/gpio.h>
#include <libopencm3/stm32/nvic.h>
#include <libopencm3/stm32/exti.h>

#define FALLING 0
#define RISING 1

u16 exti_direction = FALLING;

/* Set STM32 to 72 MHz. */
void clock_setup(void)
{
	rcc_clock_setup_in_hse_8mhz_out_72mhz();
}

void gpio_setup(void)
{
	/* Enable GPIOC clock. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPCEN);

	/* Set GPIO12 (in GPIO port C) to 'output push-pull'. */
	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ,
		      GPIO_CNF_OUTPUT_PUSHPULL, GPIO12);
}

void exti_setup(void)
{
	/* Enable GPIOA clock. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN);

	/* Enable AFIO clock. */
	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN);

	/* Enable EXTI0 interrupt. */
	nvic_enable_irq(NVIC_EXTI0_IRQ);

	/* Set GPIO0 (in GPIO port A) to 'input open-drain'. */
	gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO0);

	/* Configure the EXTI subsystem. */
	exti_select_source(EXTI0, GPIOA);
	exti_direction = FALLING;
	exti_set_trigger(EXTI0, EXTI_TRIGGER_FALLING);
	exti_enable_request(EXTI0);
}

void exti0_isr(void)
{
	exti_reset_request(EXTI0);

	if (exti_direction == FALLING) {
		gpio_set(GPIOC, GPIO12);
		exti_direction = RISING;
		exti_set_trigger(EXTI0, EXTI_TRIGGER_RISING);
	} else {
		gpio_clear(GPIOC, GPIO12);
		exti_direction = FALLING;
		exti_set_trigger(EXTI0, EXTI_TRIGGER_FALLING);
	}
}

int main(void)
{
	clock_setup();
	gpio_setup();
	exti_setup();

	while (1)
		__asm("nop");

	return 0;
}