#include <msp430g2553.h>
#include <stdio.h>
#include <isr_compat.h>

#include "uart.h"



volatile uint8_t txBuffer[UART_TX_BUFFER_SIZE+5];

volatile uint8_t txBufferReadIdx = 0;
volatile uint8_t txBufferWriteIdx = 0;

volatile uint8_t rxBuffer[UART_RX_BUFFER_SIZE+5];
volatile uint8_t rxBufferReadIdx = 0;
volatile uint8_t rxBufferWriteIdx = 0;


static inline void enableDataRegisterEmptyInterrupt() {
  IE2 |= UCA0TXIE;
}

static inline void disableDataRegisterEmptyInterrupt() {
  IE2 &= ~UCA0TXIE;
}

void uartInit() {
  UCA0CTL1 |= UCSWRST;

  P1SEL = BIT1 + BIT2;
  P1SEL2 = BIT1 + BIT2;

  UCA0CTL0 |= UCPEN | UCPAR; // even parity
  UCA0CTL1 |= UCSSEL0; // ACLK

  UCA0BR0 = 13;
  UCA0BR1 = 0;

  UCA0MCTL = UCBRS1 | UCBRS2;

  UCA0CTL1 &= ~UCSWRST;

  IE2 |= UCA0RXIE;
}


void uartWrite(uint8_t o) {
  if (txBufferWriteIdx == (UART_TX_BUFFER_SIZE - 1)) {
    while (txBufferReadIdx == UART_TX_BUFFER_SIZE);
  } else {
    while (txBufferReadIdx == (txBufferWriteIdx + 1));
  }

  txBuffer[txBufferWriteIdx] = o;
  txBufferWriteIdx++;

  if (txBufferWriteIdx > UART_TX_BUFFER_SIZE) {
    txBufferWriteIdx = 0;
  }

  enableDataRegisterEmptyInterrupt();
}


//int uartPutchar(char c, FILE *stream) {
//  if (c == '\n')
//    uartPutchar('\r', stream);
//  uartWrite((uint8_t) c);
//  return 0;
//}



ISR(USCIAB0TX, UART_TX_ISR) {
	  if ((IFG2 & UCA0TXIE) != 0) {
	    if (txBufferReadIdx != txBufferWriteIdx) {
	      UCA0TXBUF = txBuffer[txBufferReadIdx];
	      txBufferReadIdx++;
	      if (txBufferReadIdx > UART_TX_BUFFER_SIZE) {
	        txBufferReadIdx = 0;
	      }
	    } else {
	      disableDataRegisterEmptyInterrupt();
	    }
	  }
}

ISR(USCIAB0RX, UART_RX_ISR) {
  while ((IFG2 & UCA0RXIE) != 0) {
    if (rxBufferWriteIdx == UART_RX_BUFFER_SIZE - 1) {
      if (rxBufferReadIdx == UART_RX_BUFFER_SIZE) {
        // rx buffer overflow
      }
    } else {
      if (rxBufferReadIdx == rxBufferWriteIdx + 1) {
        // rx buffer overflow
      }
    }

    rxBuffer[rxBufferWriteIdx] = UCA0RXBUF;
    rxBufferWriteIdx++;

    if (rxBufferWriteIdx > UART_RX_BUFFER_SIZE) {
      rxBufferWriteIdx = 0;
    }
  }
}

uint8_t uartHasChar() {
  return rxBufferWriteIdx != rxBufferReadIdx;
}

uint8_t uartGetChar() {
  uint8_t c = rxBuffer[rxBufferReadIdx];
  rxBufferReadIdx++;
  if (rxBufferReadIdx > UART_RX_BUFFER_SIZE) {
    rxBufferReadIdx = 0;
  }
  return c;
}

int uartRead() {
  int res = -1;
  if (uartHasChar()) {
    res = uartGetChar();
  }
  return res;
}