43 lines
1.9 KiB
JavaScript
43 lines
1.9 KiB
JavaScript
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export const fromUtf8 = (input) => {
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const bytes = [];
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for (let i = 0, len = input.length; i < len; i++) {
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const value = input.charCodeAt(i);
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if (value < 0x80) {
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bytes.push(value);
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}
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else if (value < 0x800) {
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bytes.push((value >> 6) | 0b11000000, (value & 0b111111) | 0b10000000);
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}
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else if (i + 1 < input.length && (value & 0xfc00) === 0xd800 && (input.charCodeAt(i + 1) & 0xfc00) === 0xdc00) {
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const surrogatePair = 0x10000 + ((value & 0b1111111111) << 10) + (input.charCodeAt(++i) & 0b1111111111);
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bytes.push((surrogatePair >> 18) | 0b11110000, ((surrogatePair >> 12) & 0b111111) | 0b10000000, ((surrogatePair >> 6) & 0b111111) | 0b10000000, (surrogatePair & 0b111111) | 0b10000000);
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}
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else {
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bytes.push((value >> 12) | 0b11100000, ((value >> 6) & 0b111111) | 0b10000000, (value & 0b111111) | 0b10000000);
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}
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}
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return Uint8Array.from(bytes);
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};
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export const toUtf8 = (input) => {
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let decoded = "";
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for (let i = 0, len = input.length; i < len; i++) {
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const byte = input[i];
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if (byte < 0x80) {
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decoded += String.fromCharCode(byte);
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}
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else if (0b11000000 <= byte && byte < 0b11100000) {
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const nextByte = input[++i];
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decoded += String.fromCharCode(((byte & 0b11111) << 6) | (nextByte & 0b111111));
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}
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else if (0b11110000 <= byte && byte < 0b101101101) {
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const surrogatePair = [byte, input[++i], input[++i], input[++i]];
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const encoded = "%" + surrogatePair.map((byteValue) => byteValue.toString(16)).join("%");
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decoded += decodeURIComponent(encoded);
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}
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else {
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decoded += String.fromCharCode(((byte & 0b1111) << 12) | ((input[++i] & 0b111111) << 6) | (input[++i] & 0b111111));
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}
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}
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return decoded;
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};
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