can_ring.c File Reference

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Functions
void	can_ring_init (CAN_RING *ring, CAN_FRAME *frame_buf, int buf_len)
	Initializes the given CAN_RING struct with the allocated CAN_FRAME array/buffer and the length of that array/buffer.
int	can_ring_pop (CAN_RING *ring, CAN_FRAME *frame)
	Pops the oldest CAN_FRAME into the allocated struct given by the pointer.
int	can_ring_push (CAN_RING *ring, CAN_FRAME *frame)
	Pushes the CAN_FRAME onto the CAN_RING buffer.

---

Detailed Description

Author:

Tommy Craig and Jason Cortell

Ring buffers for CAN packets.

Definition in file can_ring.c.

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Function Documentation

void can_ring_init	(	CAN_RING *	ring,
		CAN_FRAME *	frame_buf,
		int	buf_len
	)

Initializes the given CAN_RING struct with the allocated CAN_FRAME array/buffer and the length of that array/buffer.

Parameters:

	ring	A pointer to the CAN_RING struct to setup.
	frame_buf	A pointer to an allocated array of CAN_FRAME structs.
	buf_len	The length of the given array.

Definition at line 26 of file can_ring.c.

                                                                       {
  ring->buf = frame_buf;
  ring->buf_len = buf_len;
  /*
  ring->in_idx = buf_len - 1;
  ring->out_idx = buf_len - 1;
  */
  ring->in_idx = 0;
  ring->out_idx = 0;
}

int can_ring_pop	(	CAN_RING *	ring,
		CAN_FRAME *	frame
	)

Pops the oldest CAN_FRAME into the allocated struct given by the pointer.

Parameters:

	ring	A pointer to the CAN_RING struct.
	frame	An empty allocated frame to put the popped frame into.

Returns:

0 if successful, 1 if buffer is empty.

Definition at line 79 of file can_ring.c.

                                                    {
 
  if (ring->out_idx != ring->in_idx)
  {
    *frame = ring->buf[ring->out_idx];
    if (ring->out_idx == (ring->buf_len) - 1)
    {
      ring->out_idx = 0;
    }
    else
    {
      ++ring->out_idx;
    }
    return 0;   //frame popped successfully
  }
  else
  {
    return 1;   //buffer empty
  }
 
 /* int out_idx = ring->out_idx;
  int  ret;
  int next_out_idx = out_idx + 1;

  if(next_out_idx >= ring->buf_len){
    next_out_idx -= ring->buf_len;
  }
  if(out_idx == ring->in_idx){
    ret = 1;
  } else {
    *frame = ring->buf[next_out_idx];
    ret = 0;
    ring->out_idx = next_out_idx;
  }
  return ret;

  */
}

int can_ring_push	(	CAN_RING *	ring,
		CAN_FRAME *	frame
	)

Pushes the CAN_FRAME onto the CAN_RING buffer.

If the buffer is full, new data is lost.

Parameters:

	ring	A pointer to the CAN_RING struct.
	frame	A pointer to the CAN_FRAME to add to the ring buffer.

Returns:

0 if successful, 1 if buffer is already full.

Definition at line 44 of file can_ring.c.

                                                      {
 // int  ret;
  int next_in_idx;
  /*
  int next_in_idx = ring->in_idx + 1;

  if(next_in_idx >= ring->buf_len){
    next_in_idx -= ring->buf_len;
  }  
  if(next_in_idx == ring->out_idx) {
    ret = 1;
  } else {
    ring->buf[next_in_idx] = *frame;
    ret = 0;
    ring->in_idx = next_in_idx;
  }
  */

  next_in_idx = ring->in_idx;
  if (++next_in_idx == ring->buf_len) {next_in_idx = 0;}
  if (next_in_idx == ring->out_idx) {return 1;} //buffer full

  ring->buf[next_in_idx] = *frame;
  ring->in_idx = next_in_idx;

  return 0;
}