/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.com>
 *
 * 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/>.
 */

/* This version derived from fancy blink */

#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/cm3/systick.h>

/*
 * Definitions for functions being abstracted out
 */
void msleep(uint32_t);
void clock_setup(void);

/* monotonically increasing number of milliseconds from reset
 * overflows every 49 days if you're wondering
 */
volatile uint32_t system_millis;

/* Called when systick fires */
void sys_tick_handler(void) {
	system_millis++;
}

/* sleep for delay milliseconds */
void msleep(uint32_t delay) {
	uint32_t wake = system_millis + delay;
	while (wake > system_millis) ;
}


/*
 * clock_setup(void)
 *
 * This function sets up both the base board clock rate
 * and a 1khz "system tick" count. The SYSTICK counter is
 * a standard feature of the Cortex-M series.
 */
void clock_setup(void)
{
	/* Base board frequency, set to 168Mhz */
	rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_168MHZ]);

	/* clock rate / 168000 to get 1mS interrupt rate */
	systick_set_reload(168000);
	systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
	systick_counter_enable();

	/* this done last */
	systick_interrupt_enable();
}

int main(void)
{
	/* Set up clock and systick */
	clock_setup();

	/* Enable GPIOD clock. */
	rcc_periph_clock_enable(RCC_GPIOG);

	/* Set GPIO13-14 (in GPIO port G) to 'output push-pull'. */
	gpio_mode_setup(GPIOG, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO13 | GPIO14);

	/* Set LED for alternating effect when toggling. */
	gpio_set(GPIOG, GPIO13);

	/* Blink the LEDs (PD12, PD13, PD14 and PD15) on the board. */
	while (1) {
		gpio_toggle(GPIOG, GPIO13 | GPIO14);
		/* Now sleep for 100ms which toggles at 10hz rate */
		msleep(100);
	}

	return 0;
}