write-token.js

// write-token.js

var ieee754 = require("ieee754");
var Int64Buffer = require("int64-buffer");
var Uint64BE = Int64Buffer.Uint64BE;
var Int64BE = Int64Buffer.Int64BE;

var uint8 = require("./write-uint8").uint8;
var Bufferish = require("./bufferish");
var Buffer = Bufferish.global;
var IS_BUFFER_SHIM = Bufferish.hasBuffer && ("TYPED_ARRAY_SUPPORT" in Buffer);
var NO_TYPED_ARRAY = IS_BUFFER_SHIM && !Buffer.TYPED_ARRAY_SUPPORT;
var Buffer_prototype = Bufferish.hasBuffer && Buffer.prototype || {};

exports.getWriteToken = getWriteToken;

function getWriteToken(options) {
  if (options && options.uint8array) {
    return init_uint8array();
  } else if (NO_TYPED_ARRAY || (Bufferish.hasBuffer && options && options.safe)) {
    return init_safe();
  } else {
    return init_token();
  }
}

function init_uint8array() {
  var token = init_token();

  // float 32 -- 0xca
  // float 64 -- 0xcb
  token[0xca] = writeN(0xca, 4, writeFloatBE);
  token[0xcb] = writeN(0xcb, 8, writeDoubleBE);

  return token;
}

// Node.js and browsers with TypedArray

function init_token() {
  // (immediate values)
  // positive fixint -- 0x00 - 0x7f
  // nil -- 0xc0
  // false -- 0xc2
  // true -- 0xc3
  // negative fixint -- 0xe0 - 0xff
  var token = uint8.slice();

  // bin 8 -- 0xc4
  // bin 16 -- 0xc5
  // bin 32 -- 0xc6
  token[0xc4] = write1(0xc4);
  token[0xc5] = write2(0xc5);
  token[0xc6] = write4(0xc6);

  // ext 8 -- 0xc7
  // ext 16 -- 0xc8
  // ext 32 -- 0xc9
  token[0xc7] = write1(0xc7);
  token[0xc8] = write2(0xc8);
  token[0xc9] = write4(0xc9);

  // float 32 -- 0xca
  // float 64 -- 0xcb
  token[0xca] = writeN(0xca, 4, (Buffer_prototype.writeFloatBE || writeFloatBE), true);
  token[0xcb] = writeN(0xcb, 8, (Buffer_prototype.writeDoubleBE || writeDoubleBE), true);

  // uint 8 -- 0xcc
  // uint 16 -- 0xcd
  // uint 32 -- 0xce
  // uint 64 -- 0xcf
  token[0xcc] = write1(0xcc);
  token[0xcd] = write2(0xcd);
  token[0xce] = write4(0xce);
  token[0xcf] = writeN(0xcf, 8, writeUInt64BE);

  // int 8 -- 0xd0
  // int 16 -- 0xd1
  // int 32 -- 0xd2
  // int 64 -- 0xd3
  token[0xd0] = write1(0xd0);
  token[0xd1] = write2(0xd1);
  token[0xd2] = write4(0xd2);
  token[0xd3] = writeN(0xd3, 8, writeInt64BE);

  // str 8 -- 0xd9
  // str 16 -- 0xda
  // str 32 -- 0xdb
  token[0xd9] = write1(0xd9);
  token[0xda] = write2(0xda);
  token[0xdb] = write4(0xdb);

  // array 16 -- 0xdc
  // array 32 -- 0xdd
  token[0xdc] = write2(0xdc);
  token[0xdd] = write4(0xdd);

  // map 16 -- 0xde
  // map 32 -- 0xdf
  token[0xde] = write2(0xde);
  token[0xdf] = write4(0xdf);

  return token;
}

// safe mode: for old browsers and who needs asserts

function init_safe() {
  // (immediate values)
  // positive fixint -- 0x00 - 0x7f
  // nil -- 0xc0
  // false -- 0xc2
  // true -- 0xc3
  // negative fixint -- 0xe0 - 0xff
  var token = uint8.slice();

  // bin 8 -- 0xc4
  // bin 16 -- 0xc5
  // bin 32 -- 0xc6
  token[0xc4] = writeN(0xc4, 1, Buffer.prototype.writeUInt8);
  token[0xc5] = writeN(0xc5, 2, Buffer.prototype.writeUInt16BE);
  token[0xc6] = writeN(0xc6, 4, Buffer.prototype.writeUInt32BE);

  // ext 8 -- 0xc7
  // ext 16 -- 0xc8
  // ext 32 -- 0xc9
  token[0xc7] = writeN(0xc7, 1, Buffer.prototype.writeUInt8);
  token[0xc8] = writeN(0xc8, 2, Buffer.prototype.writeUInt16BE);
  token[0xc9] = writeN(0xc9, 4, Buffer.prototype.writeUInt32BE);

  // float 32 -- 0xca
  // float 64 -- 0xcb
  token[0xca] = writeN(0xca, 4, Buffer.prototype.writeFloatBE);
  token[0xcb] = writeN(0xcb, 8, Buffer.prototype.writeDoubleBE);

  // uint 8 -- 0xcc
  // uint 16 -- 0xcd
  // uint 32 -- 0xce
  // uint 64 -- 0xcf
  token[0xcc] = writeN(0xcc, 1, Buffer.prototype.writeUInt8);
  token[0xcd] = writeN(0xcd, 2, Buffer.prototype.writeUInt16BE);
  token[0xce] = writeN(0xce, 4, Buffer.prototype.writeUInt32BE);
  token[0xcf] = writeN(0xcf, 8, writeUInt64BE);

  // int 8 -- 0xd0
  // int 16 -- 0xd1
  // int 32 -- 0xd2
  // int 64 -- 0xd3
  token[0xd0] = writeN(0xd0, 1, Buffer.prototype.writeInt8);
  token[0xd1] = writeN(0xd1, 2, Buffer.prototype.writeInt16BE);
  token[0xd2] = writeN(0xd2, 4, Buffer.prototype.writeInt32BE);
  token[0xd3] = writeN(0xd3, 8, writeInt64BE);

  // str 8 -- 0xd9
  // str 16 -- 0xda
  // str 32 -- 0xdb
  token[0xd9] = writeN(0xd9, 1, Buffer.prototype.writeUInt8);
  token[0xda] = writeN(0xda, 2, Buffer.prototype.writeUInt16BE);
  token[0xdb] = writeN(0xdb, 4, Buffer.prototype.writeUInt32BE);

  // array 16 -- 0xdc
  // array 32 -- 0xdd
  token[0xdc] = writeN(0xdc, 2, Buffer.prototype.writeUInt16BE);
  token[0xdd] = writeN(0xdd, 4, Buffer.prototype.writeUInt32BE);

  // map 16 -- 0xde
  // map 32 -- 0xdf
  token[0xde] = writeN(0xde, 2, Buffer.prototype.writeUInt16BE);
  token[0xdf] = writeN(0xdf, 4, Buffer.prototype.writeUInt32BE);

  return token;
}

function write1(type) {
  return function(encoder, value) {
    var offset = encoder.reserve(2);
    var buffer = encoder.buffer;
    buffer[offset++] = type;
    buffer[offset] = value;
  };
}

function write2(type) {
  return function(encoder, value) {
    var offset = encoder.reserve(3);
    var buffer = encoder.buffer;
    buffer[offset++] = type;
    buffer[offset++] = value >>> 8;
    buffer[offset] = value;
  };
}

function write4(type) {
  return function(encoder, value) {
    var offset = encoder.reserve(5);
    var buffer = encoder.buffer;
    buffer[offset++] = type;
    buffer[offset++] = value >>> 24;
    buffer[offset++] = value >>> 16;
    buffer[offset++] = value >>> 8;
    buffer[offset] = value;
  };
}

function writeN(type, len, method, noAssert) {
  return function(encoder, value) {
    var offset = encoder.reserve(len + 1);
    encoder.buffer[offset++] = type;
    method.call(encoder.buffer, value, offset, noAssert);
  };
}

function writeUInt64BE(value, offset) {
  new Uint64BE(this, offset, value);
}

function writeInt64BE(value, offset) {
  new Int64BE(this, offset, value);
}

function writeFloatBE(value, offset) {
  ieee754.write(this, value, offset, false, 23, 4);
}

function writeDoubleBE(value, offset) {
  ieee754.write(this, value, offset, false, 52, 8);
}