/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.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/>.
 */

#define _GNU_SOURCE
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>
#include <stdio.h>
#include <errno.h>
#include <stddef.h>
#include <sys/types.h>

static ssize_t _iord(void *_cookie, char *_buf, size_t _n);
static ssize_t _iowr(void *_cookie, const char *_buf, size_t _n);

static ssize_t _iord(void *_cookie, char *_buf, size_t _n)
{
	/* dont support reading now */
	(void)_cookie;
	(void)_buf;
	(void)_n;
	return 0;
}

static ssize_t _iowr(void *_cookie, const char *_buf, size_t _n)
{
	uint32_t dev = (uint32_t)_cookie;

	int written = 0;
	while (_n-- > 0) {
		usart_send_blocking(dev, *_buf++);
		written++;
	};
	return written;
}


static FILE *usart_setup(uint32_t dev)
{
	/* Setup USART parameters. */
	usart_set_baudrate(dev, 115200);
	usart_set_databits(dev, 8);
	usart_set_parity(dev, USART_PARITY_NONE);
	usart_set_stopbits(dev, USART_CR2_STOPBITS_1);
	usart_set_mode(dev, USART_MODE_TX_RX);
	usart_set_flow_control(dev, USART_FLOWCONTROL_NONE);

	/* Finally enable the USART. */
	usart_enable(dev);

	cookie_io_functions_t stub = { _iord, _iowr, NULL, NULL };
	FILE *fp = fopencookie((void *)dev, "rw+", stub);
	/* Do not buffer the serial line */
	setvbuf(fp, NULL, _IONBF, 0);
	return fp;

}

static void clock_setup(void)
{
	/* Enable GPIOC clock for LED & USARTs. */
	rcc_periph_clock_enable(RCC_GPIOC);
	rcc_periph_clock_enable(RCC_GPIOA);

	/* Enable clocks for USART. */
	rcc_periph_clock_enable(RCC_USART1);
}

static void gpio_setup(void)
{
	/* Setup GPIO pin GPIO8/9 on GPIO port C for LEDs. */
	gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO8 | GPIO9);

	/* Setup GPIO pins for USART transmit. */
	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO9);

	/* Setup USART TX pin as alternate function. */
	gpio_set_af(GPIOA, GPIO_AF1, GPIO9);
}

int main(void)
{
	int i, c = 0;
	FILE *fp;

	clock_setup();
	gpio_setup();
	fp = usart_setup(USART1);

	/* Blink the LED on the board with every transmitted byte. */
	while (1) {
		gpio_toggle(GPIOC, GPIO8);	/* LED on/off */

		fprintf(fp, "Pass: %d\n", c);

		c = (c == 200) ? 0 : c + 1;	/* Increment c. */

		for (i = 0; i < 1000000; i++) {	/* Wait a bit. */
			__asm__("NOP");
		}
	}

	return 0;
}