/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2014 Nikolay Merinov <nikolay.merinov@member.fsf.org>
 *
 * 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/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/l1/lcd.h>

static void lcd_init(void)
{
	/* Move all needed GPIO pins to LCD alternative mode */
	rcc_peripheral_enable_clock (&RCC_AHBENR, RCC_AHBENR_GPIOAEN
				     | RCC_AHBENR_GPIOBEN | RCC_AHBENR_GPIOCEN);
	rcc_peripheral_enable_clock (&RCC_AHBLPENR, RCC_AHBLPENR_GPIOALPEN
				     | RCC_AHBLPENR_GPIOBLPEN | RCC_AHBLPENR_GPIOCLPEN);
	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO1 | GPIO2
			| GPIO3 | GPIO8 | GPIO9 | GPIO10 | GPIO15);
	gpio_mode_setup(GPIOB, GPIO_MODE_AF, GPIO_PUPD_NONE,
			GPIO3 | GPIO4 | GPIO5 | GPIO8 | GPIO9 | GPIO10 | GPIO11
			| GPIO12 | GPIO13 | GPIO14 | GPIO15);
	gpio_mode_setup(GPIOC, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO0 | GPIO1
			| GPIO2 | GPIO3 | GPIO6 | GPIO7 | GPIO8 | GPIO9
			| GPIO10 | GPIO11);

	gpio_set_af (GPIOA, GPIO_AF11, GPIO1 | GPIO2 | GPIO3 | GPIO8 | GPIO9
		     | GPIO10 | GPIO15);
	gpio_set_af (GPIOB, GPIO_AF11, GPIO3 | GPIO4 | GPIO5 | GPIO8 | GPIO9
		     | GPIO10 | GPIO11 | GPIO12 | GPIO13 | GPIO14 | GPIO15);
	gpio_set_af (GPIOC, GPIO_AF11, GPIO0 | GPIO1 | GPIO2 | GPIO3 | GPIO6
		     | GPIO7 | GPIO8 | GPIO9 | GPIO10 | GPIO11);

	/* Enable LCD and use LSE clock as RTC/LCD clock.	*/
	rcc_peripheral_enable_clock (&RCC_APB1ENR, RCC_APB1ENR_PWREN | RCC_APB1ENR_LCDEN);
	pwr_disable_backup_domain_write_protect ();
	rcc_osc_on (LSE);
	rcc_wait_for_osc_ready (LSE);
	rcc_rtc_select_clock (RCC_CSR_RTCSEL_LSE);
	RCC_CSR |= RCC_CSR_RTCEN;	/* Enable RTC clock */
	pwr_enable_backup_domain_write_protect ();

	/* Map SEG[43:40] to SEG[31:28], use 4 LCD commons, use 3 voltage levels
		 when driving LCD display */
	lcd_enable_segment_multiplexing ();
	lcd_set_duty (LCD_CR_DUTY_1_4);
	lcd_set_bias (LCD_CR_BIAS_1_3);

	/* Set screen redraw frequency to 100Hz */
	lcd_set_refresh_frequency (100);
	/* And increase contrast */
	lcd_set_contrast (LCD_FCR_CC_5);

	lcd_enable ();
	do {} while (!lcd_is_enabled ());
	do {} while (!lcd_is_step_up_ready ());
}

static void clear_lcd_ram(void)
{
	LCD_RAM_COM0 = 0;
	LCD_RAM_COM1 = 0;
	LCD_RAM_COM2 = 0;
	LCD_RAM_COM3 = 0;
}

/*	LCD MAPPING:
	    A
     _  ----------
COL |_| |\   |J  /|
       F| H  |  K |B
     _  |  \ | /  |
COL |_| --G-- --M--
        |   /| \  |
       E|  Q |  N |C
     _  | /  |P  \|
DP  |_| -----------
	    D

`mask' corresponds to bits in lexicographic order: mask & 1 == A, mask & 2 == B,
and so on.
 */
static void write_mask_to_lcd_ram (int position, uint16_t mask, int clear_before)
{
	/* Every pixel of character at position can be accessed
	   as LCD_RAM_COMx & (1 << Px) */
	int P1,P2,P3,P4;
	if (position < 2) P1 = 2*position;
	else P1 = 2*position+4;
	
	if (position == 1) P2 = P1+5;
	else P2 = P1+1;
	
	if (position < 3) P3 = (23-2*position)+6;
	else P3 = (23-2*position)+4;
	
	if (position == 5) {
		P4 = P3;
		P3 -= 1;
	} else {
		P4 = P3 - 1;
	}

	uint32_t COM0,COM1,COM2,COM3;
	COM0 = LCD_RAM_COM0;
	COM1 = LCD_RAM_COM1;
	COM2 = LCD_RAM_COM2;
	COM3 = LCD_RAM_COM3;
	
	if (clear_before) {
		COM0&= ~(1<<P1 | 1<<P2 | 1<<P3 | 1<<P4);
		COM1&= ~(1<<P1 | 1<<P2 | 1<<P3 | 1<<P4);
		COM2&= ~(1<<P1 | 1<<P2 | 1<<P3 | 1<<P4);
		COM3&= ~(1<<P1 | 1<<P2 | 1<<P3 | 1<<P4);
	}
	
	COM0 |= ((mask >> 0x1) & 1) << P4 | ((mask >> 0x4) & 1) << P1
	      | ((mask >> 0x6) & 1) << P3 | ((mask >> 0xA) & 1) << P2;
	COM1 |= ((mask >> 0x0) & 1) << P4 | ((mask >> 0x2) & 1) << P2
	      | ((mask >> 0x3) & 1) << P1 | ((mask >> 0x5) & 1) << P3;
	COM3 |= ((mask >> 0x7) & 1) << P3 | ((mask >> 0x8) & 1) << P4
	      | ((mask >> 0xB) & 1) << P1 | ((mask >> 0xE) & 1) << P2;
	COM2 |= ((mask >> 0x9) & 1) << P4 | ((mask >> 0xC) & 1) << P1
	      | ((mask >> 0xD) & 1) << P3 | ((mask >> 0xF) & 1) << P2;

	LCD_RAM_COM0 = COM0;
	LCD_RAM_COM1 = COM1;
	LCD_RAM_COM2 = COM2;
	LCD_RAM_COM3 = COM3;
}

static void write_char_to_lcd_ram (int position, uint8_t symbol, bool clear_before)
{
	uint16_t from_ascii[0x60] = {
	  0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  /*         !       "       #       $      %        &       ' */
	  0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  /* (       )       *       +       ,       -       .       / */
	  0x0000, 0x0000, 0x3FC0, 0x1540, 0x0000, 0x0440, 0x4000, 0x2200,
	  /* 0       1       2       3       4       5       6       7 */
	  0x003F, 0x0006, 0x045B, 0x044F, 0x0466, 0x046D, 0x047D, 0x2201,
	  /* 8       9       :       ;       <       =       >       ? */
	  0x047F, 0x046F, 0x8000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
	  /* @       A       B       C       D       E       F       G */
	  0x0000, 0x0477, 0x047C, 0x0039, 0x045E, 0x0479, 0x0471, 0x043D,
	  /* H       I       J       K       L       M       N       O */
	  0x0476, 0x1109, 0x001E, 0x1B00, 0x0038, 0x02B6, 0x08B6, 0x003F,
	  /* P       Q       R       S       T       U       V       W */
	  0x0473, 0x0467, 0x0C73, 0x046D, 0x1101, 0x003E, 0x0886, 0x2836,
	  /* X       Y       Z       [       \       ]       ^       _ */
	  0x2A80, 0x1280, 0x2209, 0x0000, 0x0880, 0x0000, 0x0000, 0x0008
	};
	if (symbol > 0x60) return; // masks not defined. Nothing to display
	
	write_mask_to_lcd_ram (position, from_ascii[symbol], clear_before);
}


static void lcd_display_hello (void)
{
	do {} while (!lcd_is_for_update_ready ());
	clear_lcd_ram (); 	/* all segments off */
	write_char_to_lcd_ram (0, '*', true);
	write_char_to_lcd_ram (1, 'H', true);
	write_char_to_lcd_ram (2, 'E', true);
	write_char_to_lcd_ram (3, 'L', true);
	write_char_to_lcd_ram (4, 'L', true);
	write_char_to_lcd_ram (5, 'O', true);

	lcd_update ();
}

int main(void)
{
	int i;
	lcd_init ();

	lcd_display_hello ();

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

	return 0;
}