itoa.c

uint16_t itoa(int16_t num, unsigned char *buf, uint16_t maxlen)
{
  int ofs = maxlen;
  unsigned char *head = buf;
  int16_t abs_num = abs(num);
  do {
    *head++ = "0123456789"[abs_num % 10];
    abs_num /= 10;
  } while(abs_num != 0);
  if(num < 0) *head++ = '-';

  // Terminate&reverse the string
  *head-- = '\0';
  unsigned char *l = buf;
  unsigned char *r = head;
  while(l < r) {
        unsigned char tmp = *r;
        *r-- = *l;
        *l++ = tmp;
  }

  return head - buf + 1;
}