#include "main.h"
#include "spi.h"

/* Initialize and enable the SPI module */
void spi_initialize()
{
	P3SEL = 0x00E;  // Setup P3 for SPI mode
	P3OUT |= 0x010; // Setup P3.4 as the SS signal, active low. So, initialize it high.
	P3DIR |= 0x010; // Set up P3.4 as an output

	U0CTL = (CHAR | SYNC | MM | SWRST); // 8-bit, SPI, Master
	U0TCTL = (SSEL1 | STC | CKPH);  // Normal polarity, 3-wire
	U0BR0 = 0x002;  // SPICLK = SMCLK/2 (2=Minimum divisor)
	U0BR1 = 0x000;
	U0MCTL = 0x000;
	ME1 |= USPIE0;  // Module enable
	U0CTL &= ~SWRST;    // SPI enable
}

/* Set the baud-rate divisor. The correct value is computed by dividing
	the clock rate by the desired baud rate. The minimum divisor allowed
	is 2. */

void spi_set_divisor(unsigned int divisor)
{
	U0CTL |= SWRST;  // Temporarily disable the SPI module
	U0BR1 = divisor >> 8;
	U0BR0 = divisor;
	U0CTL &= ~SWRST;  // Re-enable SPI
}

/* Assert the CS signal, active low (CS=0) */
void spi_cs_assert()
{
	// Pin 3.4, Pin 32
	P3OUT &= ~0x010;
}

/* Deassert the CS signal (CS=1) */
void spi_cs_deassert()
{
	// Pin 3.4, Pin 32
	P3OUT |= 0x010;
}


/* Send a single byte over the SPI port */
void spi_send_byte(uint8_t input)
{
	IFG1 &= ~URXIFG0;
	/* Send the byte */
	TXBUF0 = input;
	/* Wait for the byte to be sent */
	while ((IFG1 & URXIFG0) == 0) { }
}


/* Receive a byte. Output an 0xFF (the bus idles high) to receive the byte */
uint8_t spi_rcv_byte()
{
	uint8_t tmp;
	IFG1 &= ~URXIFG0;
	/* Send the byte */
	TXBUF0 = 0xFF;
	/* Wait for the byte to be received */
	while ((IFG1 & URXIFG0) == 0) { }
	tmp = U0RXBUF;
	return (tmp);
}


/* Disable the SPI module. This function assumes the module had
 * already been initialized. */
void spi_disable()
{
	/* Put the SPI module in reset mode */
	U0CTL |= SWRST;
	/* Disable the USART module */
	ME1 &= ~USPIE0;
}

void spi_enable()
{
	/* Enable the USART module */
	ME1 |= USPIE0;
	/* Take the SPI module out of reset mode */
	U0CTL &= ~SWRST;
}