#include "project.h"

#define BUFFER_SIZE 256

ring_t rx_ring;
static uint8_t rx_ring_buf[BUFFER_SIZE];

ring_t tx_ring;
static uint8_t tx_ring_buf[BUFFER_SIZE];

void
usart1_isr (void)
{
  uint8_t data;

  /* Check if we were called because of RXNE. */
  if (((USART_CR1 (USART1) & USART_CR1_RXNEIE) != 0) &&
      ((USART_SR (USART1) & USART_SR_RXNE) != 0))
    {

      /* Retrieve the data from the peripheral. */
      data = usart_recv (USART1);

      ring_write_byte(&rx_ring,data);
    }

  /* Check if we were called because of TXE. */
  if (((USART_CR1 (USART1) & USART_CR1_TXEIE) != 0) &&
      ((USART_SR (USART1) & USART_SR_TXE) != 0))
    {

      if (ring_read_byte (&tx_ring, &data))
        {
          /*No more data, Disable the TXE interrupt, it's no longer needed. */
          USART_CR1 (USART1) &= ~USART_CR1_TXEIE;
        }
      else
        {
          usart_send (USART1, data);
        }
    }

}

int
_write (int file, char *ptr, int len)
{
  int ret;

  if (file == 1)
    {
      ret = ring_write (&tx_ring, (uint8_t *) ptr, len);

      if (ret < 0)
        ret = -ret;

      USART_CR1 (USART1) |= USART_CR1_TXEIE;
      return ret;
    }

  errno = EIO;
  return -1;
}

void
usart_queue (uint8_t d)
{

  ring_write_byte (&tx_ring, d);
  USART_CR1 (USART1) |= USART_CR1_TXEIE;

#if 0
  printf ("0x%02x ", d);
  fflush (stdout);
#endif
}


void
usart_init (void)
{
  ring_init (&tx_ring, tx_ring_buf, sizeof (tx_ring_buf));
  ring_init (&rx_ring, rx_ring_buf, sizeof (rx_ring_buf));

  /* Enable the USART1 interrupt. */
  nvic_enable_irq (NVIC_USART1_IRQ);

  /* Setup GPIO pin GPIO_USART1_RE_TX on GPIO port B for transmit. */
  gpio_set_mode (GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
                 GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);

  /* Setup GPIO pin GPIO_USART1_RE_RX on GPIO port B for receive. */
  gpio_set_mode (GPIOA, GPIO_MODE_INPUT,
                 GPIO_CNF_INPUT_FLOAT, GPIO_USART1_RX);

  /* Setup UART parameters. */
  usart_set_baudrate (USART1, 38400);
  usart_set_databits (USART1, 8);
  usart_set_stopbits (USART1, USART_STOPBITS_1);
  usart_set_parity (USART1, USART_PARITY_NONE);
  usart_set_flow_control (USART1, USART_FLOWCONTROL_NONE);
  usart_set_mode (USART1, USART_MODE_TX_RX);

  /* Enable USART1 Receive interrupt. */
  USART_CR1 (USART1) |= USART_CR1_RXNEIE;

  /* Finally enable the USART. */
  usart_enable (USART1);
}