shithub: m8c

ref: 2c4fe83c40da40a982beaffc84564e172f1e9177
dir: /slip.c/

#include "slip.h"
#include "command.h"

#include <assert.h>
#include <stddef.h>

/* This code is originally by marcinbor85, https://github.com/marcinbor85/slip
It has been simplified a bit as CRC checking etc. is not required in this
program. */

static void reset_rx(slip_handler_s *slip) {
  assert(slip != NULL);

  slip->state = SLIP_STATE_NORMAL;
  slip->size = 0;
}

slip_error_t slip_init(slip_handler_s *slip,
                       const slip_descriptor_s *descriptor) {
  assert(slip != NULL);
  assert(descriptor != NULL);
  assert(descriptor->buf != NULL);
  assert(descriptor->recv_message != NULL);

  slip->descriptor = descriptor;
  reset_rx(slip);

  return SLIP_NO_ERROR;
}

static slip_error_t put_byte_to_buffer(slip_handler_s *slip, uint8_t byte) {
  slip_error_t error = SLIP_NO_ERROR;

  assert(slip != NULL);

  if (slip->size >= slip->descriptor->buf_size) {
    error = SLIP_ERROR_BUFFER_OVERFLOW;
    reset_rx(slip);
  } else {
    slip->descriptor->buf[slip->size++] = byte;
    slip->state = SLIP_STATE_NORMAL;
  }

  return error;
}

slip_error_t slip_read_byte(slip_handler_s *slip, uint8_t byte) {
  slip_error_t error = SLIP_NO_ERROR;

  assert(slip != NULL);

  switch (slip->state) {
  case SLIP_STATE_NORMAL:
    switch (byte) {
    case SLIP_SPECIAL_BYTE_END:
      slip->descriptor->recv_message(slip->descriptor->buf, slip->size);
      reset_rx(slip);
      break;
    case SLIP_SPECIAL_BYTE_ESC:
      slip->state = SLIP_STATE_ESCAPED;
      break;
    default:
      error = put_byte_to_buffer(slip, byte);
      break;
    }
    break;

  case SLIP_STATE_ESCAPED:
    switch (byte) {
    case SLIP_ESCAPED_BYTE_END:
      byte = SLIP_SPECIAL_BYTE_END;
      break;
    case SLIP_ESCAPED_BYTE_ESC:
      byte = SLIP_SPECIAL_BYTE_ESC;
      break;
    default:
      error = SLIP_ERROR_UNKNOWN_ESCAPED_BYTE;
      reset_rx(slip);
      break;
    }

    if (error != SLIP_NO_ERROR)
      break;

    error = put_byte_to_buffer(slip, byte);
    break;
  }

  return error;
}