75 lines
2.0 KiB
TypeScript
75 lines
2.0 KiB
TypeScript
// credit https://stackoverflow.com/questions/18729405/how-to-convert-utf8-string-to-byte-array
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export function toUTF8Array(str: string) {
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let utf8 = [];
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for (let i = 0; i < str.length; i++) {
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let charcode = str.charCodeAt(i);
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if (charcode < 0x80) utf8.push(charcode);
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else if (charcode < 0x800) {
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utf8.push(0xc0 | (charcode >> 6), 0x80 | (charcode & 0x3f));
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} else if (charcode < 0xd800 || charcode >= 0xe000) {
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utf8.push(
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0xe0 | (charcode >> 12),
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0x80 | ((charcode >> 6) & 0x3f),
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0x80 | (charcode & 0x3f),
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);
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}
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// surrogate pair
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else {
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i++;
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// UTF-16 encodes 0x10000-0x10FFFF by
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// subtracting 0x10000 and splitting the
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// 20 bits of 0x0-0xFFFFF into two halves
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charcode =
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0x10000 + (((charcode & 0x3ff) << 10) | (str.charCodeAt(i) & 0x3ff));
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utf8.push(
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0xf0 | (charcode >> 18),
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0x80 | ((charcode >> 12) & 0x3f),
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0x80 | ((charcode >> 6) & 0x3f),
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0x80 | (charcode & 0x3f),
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);
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}
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}
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return utf8;
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}
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//courtesy https://gist.github.com/joni/3760795
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export function fromUTF8Array(data: number[]) {
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// array of bytes
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let str = '',
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i;
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for (i = 0; i < data.length; i++) {
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const value = data[i];
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if (value < 0x80) {
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str += String.fromCharCode(value);
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} else if (value > 0xbf && value < 0xe0) {
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str += String.fromCharCode(((value & 0x1f) << 6) | (data[i + 1] & 0x3f));
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i += 1;
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} else if (value > 0xdf && value < 0xf0) {
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str += String.fromCharCode(
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((value & 0x0f) << 12) |
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((data[i + 1] & 0x3f) << 6) |
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(data[i + 2] & 0x3f),
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);
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i += 2;
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} else {
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// surrogate pair
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const charCode =
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(((value & 0x07) << 18) |
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((data[i + 1] & 0x3f) << 12) |
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((data[i + 2] & 0x3f) << 6) |
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(data[i + 3] & 0x3f)) -
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0x010000;
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str += String.fromCharCode(
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(charCode >> 10) | 0xd800,
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(charCode & 0x03ff) | 0xdc00,
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);
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i += 3;
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}
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}
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return str;
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}
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