“use strict”; var Buffer = require(“safer-buffer”).Buffer;

// Single-byte codec. Needs a 'chars' string parameter that contains 256 or 128 chars that // correspond to encoded bytes (if 128 - then lower half is ASCII).

exports._sbcs = SBCSCodec; function SBCSCodec(codecOptions, iconv) {

if (!codecOptions)
    throw new Error("SBCS codec is called without the data.")

// Prepare char buffer for decoding.
if (!codecOptions.chars || (codecOptions.chars.length !== 128 && codecOptions.chars.length !== 256))
    throw new Error("Encoding '"+codecOptions.type+"' has incorrect 'chars' (must be of len 128 or 256)");

if (codecOptions.chars.length === 128) {
    var asciiString = "";
    for (var i = 0; i < 128; i++)
        asciiString += String.fromCharCode(i);
    codecOptions.chars = asciiString + codecOptions.chars;
}

this.decodeBuf = Buffer.from(codecOptions.chars, 'ucs2');

// Encoding buffer.
var encodeBuf = Buffer.alloc(65536, iconv.defaultCharSingleByte.charCodeAt(0));

for (var i = 0; i < codecOptions.chars.length; i++)
    encodeBuf[codecOptions.chars.charCodeAt(i)] = i;

this.encodeBuf = encodeBuf;

}

SBCSCodec.prototype.encoder = SBCSEncoder; SBCSCodec.prototype.decoder = SBCSDecoder;

function SBCSEncoder(options, codec) {

this.encodeBuf = codec.encodeBuf;

}

SBCSEncoder.prototype.write = function(str) {

var buf = Buffer.alloc(str.length);
for (var i = 0; i < str.length; i++)
    buf[i] = this.encodeBuf[str.charCodeAt(i)];

return buf;

}

SBCSEncoder.prototype.end = function() { }

function SBCSDecoder(options, codec) {

this.decodeBuf = codec.decodeBuf;

}

SBCSDecoder.prototype.write = function(buf) {

// Strings are immutable in JS -> we use ucs2 buffer to speed up computations.
var decodeBuf = this.decodeBuf;
var newBuf = Buffer.alloc(buf.length*2);
var idx1 = 0, idx2 = 0;
for (var i = 0; i < buf.length; i++) {
    idx1 = buf[i]*2; idx2 = i*2;
    newBuf[idx2] = decodeBuf[idx1];
    newBuf[idx2+1] = decodeBuf[idx1+1];
}
return newBuf.toString('ucs2');

}

SBCSDecoder.prototype.end = function() { }