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stringutils.js
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142 lines (132 loc) · 4.96 KB
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/**
* 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;
},
readGBKString: function(bytes, maxBytes){
console.log(bytes)
maxBytes = Math.min(maxBytes||bytes.length, bytes.length);
var array = bytes,
start = 0,
end = maxBytes;
var str = '';
var gbk = 0;
var intGBK;
for(var i=start;i<end;i++){
var item = array[i];
if(item>128&&!intGBK){
intGBK = 1;
gbk = item;
}else{
intGBK = 0;
gbk = gbk*256+item;
str = str + (fromGBKCode(gbk)||'');
gbk = 0;
}
}
return str
},
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;
}
};