73 строки
1.6 KiB
JavaScript
73 строки
1.6 KiB
JavaScript
var b64map="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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var b64padchar="=";
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function hex2b64(h) {
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var i;
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var c;
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var ret = "";
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for(i = 0; i+3 <= h.length; i+=3) {
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c = parseInt(h.substring(i,i+3),16);
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ret += b64map.charAt(c >> 6) + b64map.charAt(c & 63);
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}
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if(i+1 == h.length) {
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c = parseInt(h.substring(i,i+1),16);
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ret += b64map.charAt(c << 2);
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}
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else if(i+2 == h.length) {
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c = parseInt(h.substring(i,i+2),16);
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ret += b64map.charAt(c >> 2) + b64map.charAt((c & 3) << 4);
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}
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while((ret.length & 3) > 0) ret += b64padchar;
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return ret;
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}
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// convert a base64 string to hex
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function b64tohex(s) {
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var ret = "";
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var i;
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var k = 0; // b64 state, 0-3
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var slop;
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var v;
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for(i = 0; i < s.length; ++i) {
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if(s.charAt(i) == b64padchar) break;
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v = b64map.indexOf(s.charAt(i));
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if(v < 0) continue;
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if(k == 0) {
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ret += int2char(v >> 2);
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slop = v & 3;
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k = 1;
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}
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else if(k == 1) {
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ret += int2char((slop << 2) | (v >> 4));
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slop = v & 0xf;
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k = 2;
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}
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else if(k == 2) {
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ret += int2char(slop);
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ret += int2char(v >> 2);
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slop = v & 3;
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k = 3;
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}
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else {
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ret += int2char((slop << 2) | (v >> 4));
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ret += int2char(v & 0xf);
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k = 0;
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}
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}
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if(k == 1)
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ret += int2char(slop << 2);
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return ret;
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}
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// convert a base64 string to a byte/number array
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function b64toBA(s) {
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//piggyback on b64tohex for now, optimize later
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var h = b64tohex(s);
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var i;
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var a = new Array();
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for(i = 0; 2*i < h.length; ++i) {
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a[i] = parseInt(h.substring(2*i,2*i+2),16);
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}
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return a;
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}
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