/* This program 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.
 *
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // standard utilities
#include <unistd.h> // standard streams
#include <errno.h> // error number utilities

/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/cm3/scb.h> // vector table definition

/* own libraries */
#include "main.h" // board definitions
#include "usart.h" // USART utilities

/* default output (i.e. for printf) */
int _write(int file, char *ptr, int len)
{
	int i;

	if (file == STDOUT_FILENO || file == STDERR_FILENO) {
		for (i = 0; i < len; i++) {
			if (ptr[i] == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
				usart_putchar_nonblocking('\r'); // a second line feed doesn't break the display
			}
			usart_putchar_nonblocking(ptr[i]); // send byte over USART
		}
		return i;
	}
	errno = EIO;
	return -1;
}

static void clock_setup(void)
{
	rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock
	rcc_periph_clock_enable(LED_RCC); //enable clock for LED
}

static void gpio_setup(void)
{
	/* set LED pin to 'output push-pull' */
	gpio_set_mode(LED_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, LED_PIN);
}

int main(void)
{
	int i, c = 0;
	
	SCB_VTOR = (uint32_t) 0x08002000; // relocate vector table because of the bootloader

	clock_setup();
	gpio_setup();
	usart_setup();
	setbuf(stdout, NULL); // set standard out buffer to NULL to immediately print	
	setbuf(stderr, NULL); // set standard error buffer to NULL to immediately print

	/* blink the LED with every transmitted character */
	while (1) {
		gpio_toggle(LED_PORT, LED_PIN);	/* LED on/off */
		printf("%c",c+'0');
		c = (c == 9) ? 0 : c + 1;	/* increment c */
		for (i = 0; i < 8000000; i++)	/* wait a bit */
			__asm__("nop");
	}

	return 0;
}