/**
 * @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 480
#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 c = vga_free_run_program_get_default_config(offset);
	// destination pins for OUT instructions
	sm_config_set_out_pins(&c, 22, 1);
	pio_gpio_init(pio, 22);
	pio_sm_set_consecutive_pindirs(pio, sm, 22, 1, true);

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

	pio_sm_set_clkdiv_int_frac(pio, sm, 1, 0);

	pio->sm->shiftctrl = (1 << PIO_SM0_SHIFTCTRL_FJOIN_TX_LSB) |
	                     (1 << PIO_SM0_SHIFTCTRL_OUT_SHIFTDIR_LSB) |
	                     (1 << PIO_SM0_SHIFTCTRL_OUT_SHIFTDIR_LSB) |
	                     (1 << PIO_SM0_SHIFTCTRL_AUTOPULL_LSB);

	pio_sm_set_enabled(pio, sm, true);
}

static void vga_sync_program_init(PIO pio, uint sm, uint offset)
{
	pio_sm_config config = vga_sync_program_get_default_config(offset);
	// destination pins for SET instructions
	sm_config_set_set_pins(&config, 20, 2);
	pio_gpio_init(pio, 20);
	pio_sm_set_consecutive_pindirs(pio, sm, 20, 2, 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()
{
	// main clock = VCO / divider1 / divider2 = 126MHz
	pll_init(pll_sys, 1, 1500 * MHZ, 6, 2);

	stdio_init_all();

	// "draw" an horizontal dotted line (?)
	for (unsigned int c = 0; c < 20; c += 3)
	{
		frames[0].data[80 * 64 + 20 + c] = 0x55;
	}
	for (unsigned int c = 0; c < 20; c += 3)
	{
		frames[0].data[80 * 128 + 20 + c] = 0x99;
	}

	// PIO and state machines
	PIO pio = pio0;

	sleep_ms(5000);

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

	// VGA sync program
	uint offset1 = pio_add_program(pio, &vga_sync_program);
	uint sm1 = pio_claim_unused_sm(pio, true);
	printf("Starting VGA sync machine on %u...\n", sm1);
	vga_sync_program_init(pio, sm1, offset1);

	printf("Welcome.\n");

	while (true)
	{
		for (size_t i = 0; i < sizeof(frames[0].data);)
		{
			// feed sync machine
			if (pio_sm_get_tx_fifo_level(pio, sm1) <= 4)
			{
				pio_sm_put_blocking(pio, sm1, 63 * 4);
				pio_sm_put_blocking(pio, sm1, 775 * 4);
			}

			// feed pixel machine
			if (!pio_sm_is_tx_fifo_full(pio, sm0))
				pio_sm_put_blocking(pio, sm0, frames[0].data[i++]);
		}
		// printf(".");

		// sleep_ms(1000);
	}
}