node-a2r-slip/lib/slip.js

RFC 1055 compliant SLIP decoder and encoder stram classes

// Generated by CoffeeScript 1.4.0
(function() {
  var END, ESC, ESC_END, ESC_ESC, SlipDecoder, SlipEncoder, stream,
    __hasProp = {}.hasOwnProperty,
    __extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };

  stream = require("stream");

  END = 0xc0;

  ESC = 0xdb;

  ESC_END = 0xdc;

  ESC_ESC = 0xde;

  SlipEncoder = (function(_super) {

    __extends(SlipEncoder, _super);

    function SlipEncoder(bufsize) {
      if (bufsize == null) {
        bufsize = 65536;
      }
      this.buffer = new Buffer(bufsize);
      this.pos = 0;
      this.writable = true;
      this.readable = true;
    }

    SlipEncoder.prototype.write = function(buffer, encoding) {
      var byte, i, len;
      try {
        if (Buffer.isBuffer(buffer)) {
          this.buffer[this.pos++] = END;
          i = 0;
          len = buffer.length;
          while (i < len) {
            if (this.pos >= this.buffer.length) {
              this.pos = 0;
              this.emit("error", new Error("Buffer is to small"));
              return false;
            }
            byte = buffer[i++];
            switch (byte) {
              case END:
                this.buffer[this.pos++] = ESC;
                this.buffer[this.pos++] = ESC_END;
                break;
              case ESC:
                this.buffer[this.pos++] = ESC;
                this.buffer[this.pos++] = ESC_ESC;
                break;
              default:
                this.buffer[this.pos++] = byte;
            }
          }
          this.buffer[this.pos++] = END;
          buffer = new Buffer(this.pos);
          this.buffer.copy(buffer, 0, 0, this.pos);
          this.pos = 0;
          this.emit("data", buffer);
        } else {
          this.write(new Buffer(buffer, encoding));
        }
      } catch (e) {
        this.emit("error", e);
      }
      return true;
    };

    SlipEncoder.prototype.end = function(buffer, encoding) {
      if (buffer) {
        this.write(buffer, encoding);
      }
      return this.emit("end");
    };

    return SlipEncoder;

  })(stream.Stream);

  SlipDecoder = (function(_super) {

    __extends(SlipDecoder, _super);

    function SlipDecoder(bufsize) {
      if (bufsize == null) {
        bufsize = 65536;
      }
      this.buffer = new Buffer(bufsize);
      this.pos = 0;
      this.writable = true;
      this.readable = true;
    }

    SlipDecoder.prototype.protocolViolation = function() {
      var buf;
      if (this.pos > 0) {
        buf = new Buffer(this.pos);
        this.buffer.copy(buf, 0, 0, this.pos);
      }
      this.lastWasEsc = false;
      this.pos = 0;
      return this.emit("error", new Error("Invalid data"), buf);
    };

    SlipDecoder.prototype.write = function(buffer, encoding) {
      var buf, byte, i, len;
      try {
        if (Buffer.isBuffer(buffer)) {
          i = 0;
          len = buffer.length;
          while (i < len) {
            byte = buffer[i++];
            if (this.pos >= this.buffer.length) {
              this.emit("error", new Error("Buffer is to small"));
              this.pos = 0;
              return false;
            }
            if (this.lastWasEsc) {
              switch (byte) {
                case ESC_END:
                  this.buffer[this.pos++] = END;
                  break;
                case ESC_ESC:
                  this.buffer[this.pos++] = ESC;
                  break;
                default:
                  this.protocolViolation();
                  return true;
              }
              this.lastWasEsc = false;
            } else {
              switch (byte) {
                case END:
                  if (this.pos > 0) {
                    buf = new Buffer(this.pos);
                    this.buffer.copy(buf, 0, 0, this.pos);
                    this.emit("data", buf);
                    this.pos = 0;
                  }
                  break;
                case ESC:
                  if ((i + 1) <= len) {
                    byte = buffer[i++];
                    switch (byte) {
                      case ESC_END:
                        this.buffer[this.pos++] = END;
                        break;
                      case ESC_ESC:
                        this.buffer[this.pos++] = ESC;
                        break;
                      default:
                        this.protocolViolation();
                        return true;
                    }
                  } else {
                    this.lastWasEsc = true;
                  }
                  break;
                default:
                  this.buffer[this.pos++] = byte;
              }
            }
          }
        } else {
          this.write(new Buffer(buffer, encoding));
        }
      } catch (e) {
        this.emit("error", e);
      }
      return true;
    };

    SlipDecoder.prototype.end = function(buffer, encoding) {
      if (buffer) {
        this.write(buffer, encoding);
      }
      return this.emit("end");
    };

    return SlipDecoder;

  })(stream.Stream);

  module.exports.SlipDecoder = SlipDecoder;

  module.exports.SlipEncoder = SlipEncoder;

  module.exports.END = END;

  module.exports.ESC = ESC;

  module.exports.ESC_END = ESC_END;

  module.exports.ESC_ESC = ESC_ESC;

}).call(this);