1  "use strict";
 2  var Buffer = require("safer-buffer").Buffer;
 3  
 4  // Single-byte codec. Needs a 'chars' string parameter that contains 256 or 128 chars that
 5  // correspond to encoded bytes (if 128 - then lower half is ASCII). 
 6  
 7  exports._sbcs = SBCSCodec;
 8  function SBCSCodec(codecOptions, iconv) {
 9      if (!codecOptions)
10          throw new Error("SBCS codec is called without the data.")
11      
12      // Prepare char buffer for decoding.
13      if (!codecOptions.chars || (codecOptions.chars.length !== 128 && codecOptions.chars.length !== 256))
14          throw new Error("Encoding '"+codecOptions.type+"' has incorrect 'chars' (must be of len 128 or 256)");
15      
16      if (codecOptions.chars.length === 128) {
17          var asciiString = "";
18          for (var i = 0; i < 128; i++)
19              asciiString += String.fromCharCode(i);
20          codecOptions.chars = asciiString + codecOptions.chars;
21      }
22  
23      this.decodeBuf = Buffer.from(codecOptions.chars, 'ucs2');
24      
25      // Encoding buffer.
26      var encodeBuf = Buffer.alloc(65536, iconv.defaultCharSingleByte.charCodeAt(0));
27  
28      for (var i = 0; i < codecOptions.chars.length; i++)
29          encodeBuf[codecOptions.chars.charCodeAt(i)] = i;
30  
31      this.encodeBuf = encodeBuf;
32  }
33  
34  SBCSCodec.prototype.encoder = SBCSEncoder;
35  SBCSCodec.prototype.decoder = SBCSDecoder;
36  
37  
38  function SBCSEncoder(options, codec) {
39      this.encodeBuf = codec.encodeBuf;
40  }
41  
42  SBCSEncoder.prototype.write = function(str) {
43      var buf = Buffer.alloc(str.length);
44      for (var i = 0; i < str.length; i++)
45          buf[i] = this.encodeBuf[str.charCodeAt(i)];
46      
47      return buf;
48  }
49  
50  SBCSEncoder.prototype.end = function() {
51  }
52  
53  
54  function SBCSDecoder(options, codec) {
55      this.decodeBuf = codec.decodeBuf;
56  }
57  
58  SBCSDecoder.prototype.write = function(buf) {
59      // Strings are immutable in JS -> we use ucs2 buffer to speed up computations.
60      var decodeBuf = this.decodeBuf;
61      var newBuf = Buffer.alloc(buf.length*2);
62      var idx1 = 0, idx2 = 0;
63      for (var i = 0; i < buf.length; i++) {
64          idx1 = buf[i]*2; idx2 = i*2;
65          newBuf[idx2] = decodeBuf[idx1];
66          newBuf[idx2+1] = decodeBuf[idx1+1];
67      }
68      return newBuf.toString('ucs2');
69  }
70  
71  SBCSDecoder.prototype.end = function() {
72  }