#include <SPI.h>
#include "dagon.h"

static const uint32_t ctrlmsg = 0b10010 | (0b0010 << 20);
static const uint32_t readbit = 1 << 23;
static const int DACSS[DACS] = {4, 10, 12, 52};

uint32_t spi_write(uint32_t v, size_t dac) {
	uint32_t r;

	digitalWrite(DACSS[dac], LOW);
	r = SPI.transfer(v >> 16 & 0xFF) << 16;
	r |= SPI.transfer(v >> 8 & 0xFF) << 8;
	r |= SPI.transfer(v & 0xFF);
	digitalWrite(DACSS[dac], HIGH);
	return v;
}

uint32_t spi_transfer(uint32_t v, size_t dac) {
	spi_write(v, dac);
	delayMicroseconds(1);
	return spi_write(0, dac);
}

void spi_init() {
	SPI.begin();
	SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE1));

	for (size_t i = 0; i < DACS; i++) {
		dg.conn[i] = false;
		dg.ch[i].used = false;
		dg.ch[i].volt = V0;
		for (size_t attempts = 0; attempts < 5; attempts++) {
			uint32_t c;

			pinMode(DACSS[i], OUTPUT);
			digitalWrite(DACSS[i], HIGH);
			spi_write(ctrlmsg, i);
			c = spi_transfer(ctrlmsg | readbit, i);
			if (ctrlmsg & 0xFF == c & 0xFF) {
				dg.conn[i] = true;
				continue;
			}
		}
	}
}

void spi_reset() {
	for (size_t i = 0; i < DACS; i++)
		spi_write(i, 0b0100 | spi_register(0b0100));
	spi_init();
}