writeByte(medium.ushr(8) and 0xff)
  writeByte(medium and 0xff)
}

@Throws(IOException::class)
internal fun BufferedSource.readMedium(): Int {
  return (
    readByte() and 0xff shl 16
      or (readByte() and 0xff shl 8)
      or (readByte() and 0xff)
  )
}

/** Run [block] until it either throws an [IOException] or completes. */
internal inline fun ignoreIoExceptions(block: () -> Unit) {
  try {

    // Read a group, one to four hex digits.
    var value = 0
    groupOffset = i
    while (i < limit) {
      val hexDigit = input[i].parseHexDigit()
      if (hexDigit == -1) break
      value = (value shl 4) + hexDigit
      i++
    }
    val groupLength = i - groupOffset
    if (groupLength == 0 || groupLength > 4) return null // Group is the wrong size.

    if (codePoint == '%'.code && i + 2 < limit) {
      val d1 = encoded[i + 1].parseHexDigit()
      val d2 = encoded[i + 2].parseHexDigit()
      if (d1 != -1 && d2 != -1) {
        writeByte((d1 shl 4) + d2)
        i += 2
        i += Character.charCount(codePoint)
        continue
      }
    } else if (codePoint == '+'.code && plusIsSpace) {
      writeByte(' '.code)
      i++
      continue

}

var optab = map[string]token.Token{
	"!": token.NOT,

	"+": token.ADD,
	"-": token.SUB,
	"*": token.MUL,
	"/": token.QUO,
	"%": token.REM,

	"<<": token.SHL,
	">>": token.SHR,

	"&":  token.AND,
	"|":  token.OR,
	"^":  token.XOR,
	"&^": token.AND_NOT,

	"==": token.EQL,
	"!=": token.NEQ,
	"<":  token.LSS,
	"<=": token.LEQ,
	">":  token.GTR,

        while (true) {
          val b = readByte()
          if (b and 0x80 != 0) { // Equivalent to (b >= 128) since b is in [0..255].
            result += b and 0x7f shl shift
            shift += 7
          } else {
            result += b shl shift // Last byte.
            break
          }
        }
        return result
      }

      /** Reads a potentially Huffman encoded byte string. */

	}

	// apply exp2 contributions
	if exp2 < -1e7 || exp2 > 1e7 {
		return nil, false // avoid excessively large exponents
	}
	if exp2 > 0 {
		z.a.abs = z.a.abs.shl(z.a.abs, uint(exp2))
	} else if exp2 < 0 {
		z.b.abs = z.b.abs.shl(z.b.abs, uint(-exp2))
	}

	z.a.neg = neg && len(z.a.abs) > 0 // 0 has no sign

	return z.norm(), true
}

	POPA:      true,
	POPCNT:    true,
	PUSH:      true,
	PUSHA:     true,
	RCL:       true,
	RCR:       true,
	ROL:       true,
	ROR:       true,
	SAR:       true,
	SBB:       true,
	SHL:       true,
	SHLD:      true,
	SHR:       true,
	SHRD:      true,
	SUB:       true,
	TEST:      true,
	XADD:      true,
	XCHG:      true,
	XOR:       true,
}

var plan9Reg = [...]string{

            if (c.isLowSurrogate() || !low.isLowSurrogate()) {
              '?'.code
            } else {
              i++
              0x010000 + (c.code and 0x03ff shl 10 or (low.code and 0x03ff))
            }
          }

          else -> c.code
        }
      i++
    }
    return result
  }

  private val Int.punycodeDigit: Int
    get() =

	{_Star, "*", Mul, precMul},
	{_Operator, "/", Div, precMul},
	{_Operator, "%", Rem, precMul},
	{_Operator, "&", And, precMul},
	{_Operator, "&^", AndNot, precMul},
	{_Operator, "<<", Shl, precMul},
	{_Operator, ">>", Shr, precMul},

	// assignment operations
	{_AssignOp, "+=", Add, precAdd},
	{_AssignOp, "-=", Sub, precAdd},
	{_AssignOp, "|=", Or, precAdd},
	{_AssignOp, "^=", Xor, precAdd},

		return i*_W + uint(bits.TrailingZeros(uint(x[i]))), true
	}
	return 0, false
}

func same(x, y nat) bool {
	return len(x) == len(y) && len(x) > 0 && &x[0] == &y[0]
}

// z = x << s
func (z nat) shl(x nat, s uint) nat {
	if s == 0 {
		if same(z, x) {
			return z
		}
		if !alias(z, x) {
			return z.set(x)
		}
	}

	m := len(x)
	if m == 0 {
		return z[:0]
	}
	// m > 0