CommandStation-EX/MemStream.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 "MemStream.h"

MemStream::MemStream(uint8_t *buffer, const uint16_t len, uint16_t content_len, bool allowWrite)
:_buffer(buffer),_len(len), _buffer_overflow(false),  _pos_read(0), _allowWrite(allowWrite)
{
  if (content_len==0) memset(_buffer, 0, _len);
  _pos_write=(content_len>len)? len: content_len;
}

size_t MemStream::write(uint8_t byte) {
  if (! _allowWrite) return -1;
  if (_pos_write >= _len) {
    _buffer_overflow = true;
    return 0;
  }
  _buffer[_pos_write] = byte;
  ++_pos_write;
  return 1;
}

void MemStream::flush() {
  memset(_buffer, 0, _len);
  _pos_write = 0;
  _pos_read = 0;
}

int MemStream::read() {
  if (_pos_read >= _len) {
    _buffer_overflow = true;
    return -1;
  }
  if (_pos_read >= _pos_write) {
    return -1;
  }
  return _buffer[_pos_read++];
}

int MemStream::peek() {
  if (_pos_read >= _len) {
    _buffer_overflow = true;
    return -1;
  }
  if (_pos_read >= _pos_write) {
    return -1;
  }
  return _buffer[_pos_read+1];
}

int MemStream::available() {
  int ret=_pos_write-_pos_read;
  if (ret<0) ret=0;
  return ret;
}

void MemStream::setBufferContent(uint8_t *buffer, uint16_t content_len) {
  memset(_buffer, 0, _len);
  memcpy(_buffer, buffer, content_len);
  _buffer_overflow=false;
  _pos_write=content_len;
  _pos_read=0;
}

void MemStream::setBufferContentFromProgmem(uint8_t *buffer, uint16_t content_len) {
  memset(_buffer, 0, _len);
  memcpy_P(_buffer, buffer, content_len);
  _buffer_overflow=false;
  _pos_write=content_len;
  _pos_read=0;
}

void MemStream::setBufferContentPosition(uint16_t read_pos, uint16_t write_pos) {
    _pos_write=write_pos;
    _pos_read=read_pos;
}