/**

* Copyright (c) 2010, António Afonso <antonio.afonso gmail.com>. All rights reserved.

*

* Redistribution and use in source and binary forms, with or without modification, are

* permitted provided that the following conditions are met:

*

* 1. Redistributions of source code must retain the above copyright notice, this list of

* conditions and the following disclaimer.

*

* 2. Redistributions in binary form must reproduce the above copyright notice, this list

* of conditions and the following disclaimer in the documentation and/or other materials

* provided with the distribution.

*

* THIS SOFTWARE IS PROVIDED BY António Afonso ``AS IS'' AND ANY EXPRESS OR IMPLIED

* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR

* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON

* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

var StringUtils = {

readUTF16String: function(bytes, bigEndian, maxBytes) {

var ix = 0;

var offset1 = 1, offset2 = 0;

maxBytes = Math.min(maxBytes||bytes.length, bytes.length);

if( bytes[0] == 0xFE && bytes[1] == 0xFF ) {

bigEndian = true;

ix = 2;

} else if( bytes[0] == 0xFF && bytes[1] == 0xFE ) {

bigEndian = false;

ix = 2;

}

if( bigEndian ) {

offset1 = 0;

offset2 = 1;

}

var arr = [];

for( var j = 0; ix < maxBytes; j++ ) {

var byte1 = bytes[ix+offset1];

var byte2 = bytes[ix+offset2];

var word1 = (byte1<<8)+byte2;

ix += 2;

if( word1 == 0x0000 ) {

break;

} else if( byte1 < 0xD8 || byte1 >= 0xE0 ) {

arr[j] = String.fromCharCode(word1);

} else {

var byte3 = bytes[ix+offset1];

var byte4 = bytes[ix+offset2];

var word2 = (byte3<<8)+byte4;

ix += 2;

arr[j] = String.fromCharCode(word1, word2);

}

}

var string = new String(arr.join(""));

string.bytesReadCount = ix;

return string;

},

readUTF8String: function(bytes, maxBytes) {

var ix = 0;

maxBytes = Math.min(maxBytes||bytes.length, bytes.length);

if( bytes[0] == 0xEF && bytes[1] == 0xBB && bytes[2] == 0xBF ) {

ix = 3;

}

var arr = [];

for( var j = 0; ix < maxBytes; j++ ) {

var byte1 = bytes[ix++];

if( byte1 == 0x00 ) {

break;

} else if( byte1 < 0x80 ) {

arr[j] = String.fromCharCode(byte1);

} else if( byte1 >= 0xC2 && byte1 < 0xE0 ) {

var byte2 = bytes[ix++];

arr[j] = String.fromCharCode(((byte1&0x1F)<<6) + (byte2&0x3F));

} else if( byte1 >= 0xE0 && byte1 < 0xF0 ) {

var byte2 = bytes[ix++];

var byte3 = bytes[ix++];

arr[j] = String.fromCharCode(((byte1&0xFF)<<12) + ((byte2&0x3F)<<6) + (byte3&0x3F));

} else if( byte1 >= 0xF0 && byte1 < 0xF5) {

var byte2 = bytes[ix++];

var byte3 = bytes[ix++];

var byte4 = bytes[ix++];

var codepoint = ((byte1&0x07)<<18) + ((byte2&0x3F)<<12)+ ((byte3&0x3F)<<6) + (byte4&0x3F) - 0x10000;

arr[j] = String.fromCharCode(

(codepoint>>10) + 0xD800,

(codepoint&0x3FF) + 0xDC00

);

}

}

var string = new String(arr.join(""));

string.bytesReadCount = ix;

return string;

},

readNullTerminatedString: function(bytes, maxBytes) {

var arr = [];

maxBytes = maxBytes || bytes.length;

for ( var i = 0; i < maxBytes; ) {

var byte1 = bytes[i++];

if( byte1 == 0x00 ) break;

arr[i-1] = String.fromCharCode(byte1);

}

var string = new String(arr.join(""));

string.bytesReadCount = i;

return string;

}

};

module.exports = StringUtils;