CommandStation-EX/RingStream.cpp

/*

 (c) 2015 Ingo Fischer
 buffer serial device
 based on Arduino SoftwareSerial

 Constructor warning messages fixed by Chris Harlow.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

*/

#include "RingStream.h"
#include "DIAG.h"

RingStream::RingStream( const uint16_t len)
{
  _len=len;
  _buffer=new byte[len];
  _pos_write=0;
  _pos_read=0;
  _buffer[0]=0;
  _overflow=false;
}

size_t RingStream::write(uint8_t byte) {
  if (_overflow) return 0;
  _buffer[_pos_write] = byte;
  ++_pos_write;
  if (_pos_write>=_len) _pos_write=0;
  if (_pos_write==_pos_read) {
    _overflow=true; 
    DIAG(F("\nRingStream(%d) OVERFLOW  %d %d \n"),_len, _pos_write, _pos_read);
    return 0;
  }
  return 1;
}

int RingStream::read() {
  if (_pos_read==_pos_write) return -1; 
  byte b=_buffer[_pos_read];
  _pos_read++;
  if (_pos_read>=_len) _pos_read=0;
  _overflow=false;
  return b;
}


int RingStream::count() {
  int peek=_pos_read;
  int counter=0;
  while(_buffer[peek]) {
    counter++;
    peek++;
    if (peek >= _len) peek=0;
  }
  return counter;
  }