/* 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
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities

/* own libraries */
#include "main.h" // board definitions
#include "usart.h" // USART utilities
#include "usb_cdcacm.h" // USB CDC ACM 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
				cdcacm_putchar('\r'); // a second line feed doesn't break the display
			}
			usart_putchar_nonblocking(ptr[i]); // send byte over USART
			cdcacm_putchar(ptr[i]); // send byte over USB
		}
		return i;
	}
	errno = EIO;
	return -1;
}

static void gpio_setup(void)
{
	rcc_periph_clock_enable(LED_RCC); //enable clock for LED
	gpio_set_mode(LED_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, LED_PIN); // set LED pin to 'output push-pull'
	
	rcc_periph_clock_enable(VFD_RCC); //enable clock for VFD
	gpio_set_mode(VFD_PORT, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, VFD_STR); // set VFD pin to 'output push-pull'
	gpio_set_mode(VFD_PORT, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, VFD_NLE); // set VFD pin to 'output push-pull'
	gpio_set_mode(VFD_PORT, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, VFD_CLK); // set VFD pin to 'output push-pull'
	gpio_set_mode(VFD_PORT, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, VFD_DIN); // set VFD pin to 'output push-pull'
	
}

/* the ten seven segments + dot displays
 * actually they also have a comma and underline, but we want to save space
 */
//static uint8_t digits[10];
/* the twelve 5x7 dot matrix displays
 * the last column dot/bit is not used, making them byte aligned
 */
//static uint8_t dots[12][5];
/* the three 32 bit to be shifted out to the VFD controller
 */
static uint32_t vfd_data[3];

/* shift out the VFD data */
static void vfd_shift(void)
{
	gpio_clear(VFD_PORT, VFD_NLE); // do not latch data
	gpio_set(VFD_PORT, VFD_CLK); // clock is idle high	
	for (uint8_t i=0; i<sizeof(vfd_data)/sizeof(vfd_data[0]); i++) {
		//printf("%08lx ",vfd_data[i]);
		for (uint8_t b=0; b<32; b++) {
			gpio_clear(VFD_PORT, VFD_CLK); // change data on low
			if (vfd_data[i]&(1<<b)) { // shift the value
				gpio_set(VFD_PORT, VFD_DIN);
			} else {
				gpio_clear(VFD_PORT, VFD_DIN);
			}
			gpio_set(VFD_PORT, VFD_CLK); // signal need to be valid on high edge
		}
	}
	//printf("\n");
	gpio_set(VFD_PORT, VFD_STR); // disable HV output
	gpio_set(VFD_PORT, VFD_NLE); // latch data
	gpio_clear(VFD_PORT, VFD_STR); // enable HV output
	gpio_clear(VFD_PORT, VFD_NLE); // stop latching data
}

/* transmit each digit and dot */
/*
static void vfd_transmit(void)
{
	// convert digits
	
}
*/

/* ASCII characters encoded for 7 segments display
 * starts with space, ends with tilde
 */
static const uint8_t ascii_7segments[] = {
	0b00000000, // space
	0b00110000, // ! (I)
	0b00100010, // "
	0b01011100, // # (o)
	0b01101101, // $ (s)
	0b01010010, // % (/)
	0b01111101, // & (6)
	0b00100000, // '
	0b00111001, // ( ([)
	0b00001111, // )
	0b01110000, // *
	0b01000110, // +
	0b00010000, // ,
	0b01000000, // -
	0b00010000, // . (,)
	0b01010010, // /
	0b00111111, // 0
	0b00000110, // 1
	0b01011011, // 2
	0b01001111, // 3
	0b01100110, // 4
	0b01101101, // 5
	0b01111101, // 6
	0b00000111, // 7
	0b01111111, // 8
	0b01101111, // 9
	0b01001000, // : (=)
	0b01001000, // ; (=)
	0b01011000, // <
	0b01001000, // =
	0b01001100, // >
	0b01010011, // ?
	0b01111011, // @
	0b01110111, // A
	0b01111111, // B
	0b00111001, // C
	0b01011110, // D
	0b01111001, // E
	0b01110001, // F
	0b00111101, // G
	0b01110110, // H
	0b00110000, // I
	0b00011110, // J
	0b01110110, // K
	0b00111000, // L
	0b00110111, // M
	0b00110111, // N
	0b00111111, // O
	0b01110011, // P
	0b01101011, // Q
	0b00110011, // R
	0b01101101, // S
	0b01111000, // T
	0b00111110, // U
	0b00111110, // V (U)
	0b00111110, // W (U)
	0b01110110, // X (H)
	0b01101110, // Y
	0b01011011, // Z
	0b00111001, // [
	0b01100100, // '\'
	0b00001111, // /
	0b00100011, // ^
	0b00001000, // _
	0b00000010, // `
	0b01011111, // a
	0b01111100, // b
	0b01011000, // c
	0b01011110, // d
	0b01111011, // e
	0b01110001, // f
	0b01101111, // g
	0b01110100, // h
	0b00010000, // i
	0b00001100, // j
	0b01110110, // k
	0b00110000, // l
	0b01010100, // m
	0b01010100, // n
	0b01011100, // o
	0b01110011, // p
	0b01100111, // q
	0b01010000, // r
	0b01101101, // s
	0b01111000, // t
	0b00011100, // u
	0b00011100, // v (u)
	0b00011100, // w (u)
	0b01110110, // x
	0b01101110, // y
	0b01011011, // z
	0b00111001, // { ([)
	0b00110000, // |
	0b00001111, // } ([)
	0b01000000, // ~
};

/* put digit into memory */
static void vfd_digit(uint8_t nb, char c)
{
	// there are only 10 digits
	if (nb>9) {
		return;
	}
	vfd_data[0] = 0;
	vfd_data[1] = 1<<(4+(9-nb)); // select digit
	/* encode segment
	 * here the bit order (classic 7 segment + underline and dot)
	 *   3_
	 * 8|9_|4
	 * 7|6_|5.1
	 *   0_2,
	 * */
	if (false) { // add the underline (not encoded)
		vfd_data[1] |= (1<<(14));
	}
	if (c&0x80) { // add the dot (encoded in the 8th bit)
		vfd_data[1] |= (1<<(15));
	}
	if (false) { // add the comma (not encoded)
		vfd_data[1] |= (1<<(16));
	}	
	if (((c&0x7f)<' ') || ((c&0x7f)>'~')) { // unknown ASCII character
		vfd_data[1] |= (ascii_7segments[' '-' ']<<(17)); // add empty segments to memory
	} else {
		vfd_data[1] |= (ascii_7segments[c-' ']<<(17)); // add encoded segments to memory
	}	
	
	vfd_data[2] = 0;
}

static void vfd_matrix(uint8_t nb, char c)
{
	(void)c;
	// there are only 12 matrix
	if (nb>11) {
		return;
	} else if (nb<4) {
		vfd_data[0] = 0;
		vfd_data[1] = 1<<(3-nb); // select digit
	} else {
		vfd_data[0] = 1<<(35-nb); // select digit
		vfd_data[1] = 0;
	}
	
	vfd_data[1] |= 0xff000000;
	vfd_data[2] = 0xffffffff;
}

int main(void)
{	
	SCB_VTOR = (uint32_t) 0x08002000; // relocate vector table because of the bootloader
	rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock

	gpio_setup(); // setup main inputs/outputs
	usart_setup(); // setup USART (for printing)
	cdcacm_setup(); // setup USB CDC ACM (for printing)
	
	setbuf(stdout, NULL); // set standard out buffer to NULL to immediately print	
	setbuf(stderr, NULL); // set standard error buffer to NULL to immediately print

	printf("welcome to the STM32F1 CuVoodoo display driver\n");
	
	gpio_set(VFD_PORT, VFD_STR); // disable HV output
	gpio_clear(VFD_PORT, VFD_NLE); // do not latch data
	gpio_set(VFD_PORT, VFD_CLK); // clock is idle high

	bool vfd_transmit = false;
	uint8_t digit = 0;
	uint8_t c = 0;
	vfd_digit(0,0);
	/* blink the LED with every transmitted character */
	while (1) {
		while (usart_received) { // echo every received character
			//gpio_toggle(LED_PORT, LED_PIN); // toggle LED
			printf("%c",usart_getchar()); // transmit receive character
			vfd_transmit = true;
		}
		while (cdcacm_received) { // echo every received character
			//gpio_toggle(LED_PORT, LED_PIN); // toggle LED
			printf("%c",cdcacm_getchar()); // transmit receive character
			vfd_transmit = true;
		}
		while (vfd_transmit) {
			vfd_transmit = false;
			c = digit+'0';
			vfd_matrix(digit,c);
			vfd_shift();
			digit = (digit+1)%12;
			// let the fluorescence glow up a bit
			for (uint32_t i = 0; i < 0x2000; i++) {
				__asm__("nop");
			}
		}
		__WFI(); // go to sleep
	}

	return 0;
}