@kayahr/text-encoding
Version:
Text encoder and decoder
59 lines • 1.96 kB
JavaScript
/*
* Copyright (C) 2021 Klaus Reimer <k@ailis.de>
* See LICENSE.md for licensing information.
*/
import jis0208 from "../../../data/jis0208.cp.js";
import jis0212 from "../../../data/jis0212.cp.js";
import { AbstractDecoder } from "../AbstractDecoder.js";
import { END_OF_BUFFER } from "../ByteBuffer.js";
import { FINISHED } from "../constants.js";
import { inRange, isASCII } from "../util.js";
/**
* Decoder for euc-jp encoding.
*/
export class EUCJPDecoder extends AbstractDecoder {
jis0212Flag = false;
lead = 0x00;
/** @inheritDoc */
decode(buffer) {
const byte = buffer.read();
if (byte === END_OF_BUFFER && this.lead !== 0x00) {
this.lead = 0x00;
return this.fail();
}
if (byte === END_OF_BUFFER && this.lead === 0x00) {
return FINISHED;
}
if (this.lead === 0x8E && inRange(byte, 0xA1, 0xDF)) {
this.lead = 0x00;
return 0xFF61 - 0xA1 + byte;
}
if (this.lead === 0x8F && inRange(byte, 0xA1, 0xFE)) {
this.jis0212Flag = true;
this.lead = byte;
return null;
}
if (this.lead !== 0x00) {
const lead = this.lead;
this.lead = 0x00;
let codePoint = null;
if (inRange(lead, 0xA1, 0xFE) && inRange(byte, 0xA1, 0xFE)) {
codePoint = (this.jis0212Flag ? jis0212 : jis0208)[(lead - 0xA1) * 94 + (byte - 0xA1)] ?? null;
}
this.jis0212Flag = false;
if (!inRange(byte, 0xA1, 0xFE)) {
buffer.write(byte);
}
return codePoint ?? this.fail();
}
if (isASCII(byte)) {
return byte;
}
if (byte === 0x8E || byte === 0x8F || inRange(byte, 0xA1, 0xFE)) {
this.lead = byte;
return null;
}
return this.fail();
}
}
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