/**
 * @file main.c
 * @author giomba@glgprograms.it
 * @brief
 *
 * @copyright Copyright Retrofficina GLG Programs (c) 2022
 *
 */

#include "hardware/clocks.h"
#include "hardware/pio.h"
#include "hardware/pll.h"
#include "hardware/structs/pio.h"
#include "pico/stdlib.h"

#include <stdint.h>

#include "vga.pio.h"

#include <stdio.h>

#define FRAMES 2

#define HPIXEL 640
#define VPIXEL 500
#define BPP    1

typedef struct Frame
{
	uint8_t data[HPIXEL * VPIXEL * BPP / 8];
} Frame;

static Frame frames[FRAMES] = {0};

static void vga_pixel_program_init(PIO pio, uint sm, uint offset)
{
	// magic definition of the called function?
	pio_sm_config config = vga_free_run_program_get_default_config(offset);
	// destination pins for OUT instructions
	sm_config_set_out_pins(&config, 22, 1);
	sm_config_set_out_shift(&config, true, true, 0);
	pio_gpio_init(pio, 22);
	pio_sm_set_consecutive_pindirs(pio, sm, 22, 1, true);

	pio_sm_init(pio, sm, offset, &config);

	pio_sm_set_clkdiv_int_frac(pio, sm, 1, 0);

	pio_sm_set_enabled(pio, sm, true);
}

static void vga_hsync_program_init(PIO pio, uint sm, uint offset)
{
	pio_sm_config config = vga_hsync_program_get_default_config(offset);
	// destination pins for SET instructions
	sm_config_set_set_pins(&config, 20, 1);
	pio_gpio_init(pio, 20);
	pio_sm_set_consecutive_pindirs(pio, sm, 20, 1, true);

	pio_sm_init(pio, sm, offset, &config);

	pio_sm_set_clkdiv_int_frac(pio, sm, 1, 0);

	pio->sm->shiftctrl = (1 << PIO_SM0_SHIFTCTRL_FJOIN_TX_LSB);

	pio_sm_set_enabled(pio, sm, true);
}

static void vga_vsync_program_init(PIO pio, uint sm, uint offset)
{
	pio_sm_config config = vga_vsync_program_get_default_config(offset);
	// destination pins for SET instructions
	sm_config_set_set_pins(&config, 21, 1);
	pio_gpio_init(pio, 21);
	pio_sm_set_consecutive_pindirs(pio, sm, 21, 1, true);

	pio_sm_init(pio, sm, offset, &config);

	pio_sm_set_clkdiv_int_frac(pio, sm, 1, 0);

	pio->sm->shiftctrl = (1 << PIO_SM0_SHIFTCTRL_FJOIN_TX_LSB);

	pio_sm_set_enabled(pio, sm, true);
}

int main()
{
	stdio_init_all();
	sleep_ms(5000);

	// "draw" an horizontal dotted line (?)
	for (unsigned int c = 0; c < 5; c++)
	{
		frames[0].data[80 * 64 + 30 + c] = 0x55;
	}

	// PIO and state machines
	PIO pio = pio0;

	// VGA HSYNC program
	uint offset1 = pio_add_program(pio, &vga_hsync_program);
	uint sm1 = pio_claim_unused_sm(pio, true);
	printf("Starting VGA sync machine on %u...\n", sm1);
	vga_hsync_program_init(pio, sm1, offset1);
	printf("Feeding horizontal sync...\n");
	// low pulse is X pixels long, and SM runs at 4x of pixel clock
	pio_sm_put_blocking(pio, sm1, (64 - 1) * 4);
	pio_sm_put_blocking(pio, sm1, (776 - 1) * 4);

	// VGA VSYNC program
	uint offset2 = pio_add_program(pio, &vga_vsync_program);
	uint sm2 = pio_claim_unused_sm(pio, true);
	printf("Starting VGA vsync machine on %u...\n", sm2);
	vga_vsync_program_init(pio, sm2, offset2);
	printf("Feeding vertical sync...\n");
	// low pulse assert lasts for 3 horizontal lines, then adjust by one
	pio_sm_put_blocking(pio, sm2, 3 - 1);
	pio_sm_put_blocking(pio, sm2, 500 - 3 - 1);
	printf("OK\n");

	// VGA pixel program
	uint offset0 = pio_add_program(pio, &vga_free_run_program);
	uint sm0 = pio_claim_unused_sm(pio, false);
	printf("Starting VGA pixel machine on %u...\n", sm0);
	vga_pixel_program_init(pio, sm0, offset0);
	pio_sm_put_blocking(pio, sm0, 640 - 1);

	printf("Start!\n");

	while (true)
	{
		for (size_t i = 0; i < sizeof(frames[0].data);)
		{
			// feed pixel machine
			pio_sm_put_blocking(pio, sm0, frames[0].data[i++]);
			// printf("%d.", i);
		}
		// sleep_ms(1000);
		// printf(".");
	}
}