#include "hardware/gpio.h"
#include "hardware/pio.h"
#include "hardware/dma.h"

#include "sseg.pio.h"

#include "sseg.h"
#include "pinout.h"

// Segment Layout:
//
// .--A--.
// |     |
// F     B
// |     |
// +--G--+
// |     |
// E     C
// |     |
// .--D--. .DP.


#define SSEG_START_PIN 0

static volatile uint32_t m_dma_buffer[4] __attribute__((aligned(4*sizeof(uint32_t *)))) = {
	0x0000013D, // segment 0 = 'Z' = '2'
	0x00000277, // segment 1 = A
	0x00000476, // segment 2 = M
	0x00000000, // dummy entry
};

static PIO m_pio;
static uint m_sm;

static int m_dma_chan;

// see doc/sseg_codes.txt for construction details
static uint8_t ascii_to_sseg(char c)
{
	switch(c) {
		case 'o':
		case 'O':
		case '0':
			return 0x7E;

		case '1':
			return 0x60;

		case 'Z':
		case '2':
			return 0x3D;

		case '3':
			return 0x79;

		case '4':
			return 0x63;

		case '5':
			return 0x5B;

		case '6':
			return 0x5F;

		case '7':
			return 0x70;

		case '8':
			return 0x7F;

		case '9':
			return 0x7B;

		case 'm':
		case 'M':
			return 0x76;

		case 'a':
		case 'A':
			return 0x77;

		case 'f':
		case 'F':
			return 0x17;

		case '#':
			return 0x66;

		case 'i':
		case 'I':
		case '|':
			return 0x06;

		case 'd':
		case 'D':
			return 0x6D;

		case 'h':
		case 'H':
			return 0x67;

		case 'n':
		case 'N':
			return 0x45;

		case ' ':
			return 0x00;

		default: // '-'
			return 0x01;
	}
}

void sseg_init(void)
{
	// set up PIO for 7-segment display
	m_pio = pio0;
	uint offset = pio_add_program(m_pio, &sseg_program);
	m_sm = pio_claim_unused_sm(m_pio, true);
	pio_sm_config c = sseg_program_get_default_config(offset);

	sm_config_set_clkdiv_int_frac(&c, 2000, 0);

	sm_config_set_out_pins(&c, SSEG_START_PIN, 11);
	sm_config_set_set_pins(&c, SSEG_START_PIN+8, 3);

	pio_gpio_init(m_pio, SSEG_A_PIN);
	pio_gpio_init(m_pio, SSEG_B_PIN);
	pio_gpio_init(m_pio, SSEG_C_PIN);
	pio_gpio_init(m_pio, SSEG_D_PIN);
	pio_gpio_init(m_pio, SSEG_E_PIN);
	pio_gpio_init(m_pio, SSEG_F_PIN);
	pio_gpio_init(m_pio, SSEG_G_PIN);
	pio_gpio_init(m_pio, SSEG_DP_PIN);
	pio_gpio_init(m_pio, SSEG_MUX_1_PIN);
	pio_gpio_init(m_pio, SSEG_MUX_2_PIN);
	pio_gpio_init(m_pio, SSEG_MUX_3_PIN);

	pio_sm_set_consecutive_pindirs(m_pio, m_sm, SSEG_START_PIN, 11, true);

	pio_sm_init(m_pio, m_sm, offset, &c);

	m_dma_chan = dma_claim_unused_channel(true);
	dma_channel_config dma_config = dma_channel_get_default_config(m_dma_chan);

	channel_config_set_transfer_data_size(&dma_config, DMA_SIZE_32);
	channel_config_set_read_increment(&dma_config, true);
	channel_config_set_write_increment(&dma_config, false);
	channel_config_set_ring(&dma_config, false, 4); // read ringbuffer with 2^4 = 16 bytes = 4 entries
	channel_config_set_dreq(&dma_config, DREQ_PIO0_TX0);

	dma_channel_configure(
			m_dma_chan,
			&dma_config,
			&pio0_hw->txf[0], // Write address (only need to set this once)
			m_dma_buffer,     // Read address
			1<<14,            // Write the buffer many times, then halt and interrupt
			true              // Start right now
			);

	pio_sm_set_enabled(m_pio, m_sm, true);
}

void sseg_loop(void)
{
	// restart the DMA channel if it has completed the transfer
	if((dma_hw->intr & (1u << m_dma_chan)) != 0) {
		dma_hw->ints0 = 1u << m_dma_chan;
		dma_channel_start(m_dma_chan);
	}
}

void sseg_set_char(uint8_t seg, char c, bool with_dot)
{
	uint dot_bit = with_dot ? 0x80 : 0x00;
	m_dma_buffer[seg] = (m_dma_buffer[seg] & 0xFFFFFF00) | dot_bit | ascii_to_sseg(c);
}