All files / buffers/src/utf8/decodeUtf8 v18.ts

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const fromCharCode = String.fromCharCode;
 
export default (buf: Uint8Array, start: number, length: number): string => {
  let offset = start;
  const end = offset + length;
  const points: number[] = [];
  while (offset < end) {
    let code = buf[offset++]!;
    if ((code & 0x80) !== 0) {
      const octet2 = buf[offset++]! & 0x3f;
      if ((code & 0xe0) === 0xc0) {
        code = ((code & 0x1f) << 6) | octet2;
      } else {
        const octet3 = buf[offset++]! & 0x3f;
        if ((code & 0xf0) === 0xe0) {
          code = ((code & 0x1f) << 12) | (octet2 << 6) | octet3;
        } else {
          if ((code & 0xf8) === 0xf0) {
            const octet4 = buf[offset++]! & 0x3f;
            let unit = ((code & 0x07) << 0x12) | (octet2 << 0x0c) | (octet3 << 0x06) | octet4;
            if (unit > 0xffff) {
              unit -= 0x10000;
              const unit0 = ((unit >>> 10) & 0x3ff) | 0xd800;
              code = 0xdc00 | (unit & 0x3ff);
              points.push(unit0);
            } else E{
              code = unit;
            }
          }
        }
      }
    }
    points.push(code);
  }
  return fromCharCode.apply(String, points);
};