// Exp10 Range.
	if man == 0 {
		if neg {
			f = math.Float64frombits(0x8000000000000000) // Negative zero.
		}
		return f, true
	}
	if exp10 < detailedPowersOfTenMinExp10 || detailedPowersOfTenMaxExp10 < exp10 {
		return 0, false
	}

	// Normalization.
	clz := bits.LeadingZeros64(man)
	man <<= uint(clz)
	const float64ExponentBias = 1023

//	exact = ε == 0
func mult64bitPow10(m uint32, e2, q int) (resM uint32, resE int, exact bool) {
	if q == 0 {
		// P == 1<<63
		return m << 6, e2 - 6, true
	}
	if q < detailedPowersOfTenMinExp10 || detailedPowersOfTenMaxExp10 < q {
		// This never happens due to the range of float32/float64 exponent
		panic("mult64bitPow10: power of 10 is out of range")
	}
	pow := detailedPowersOfTen[q-detailedPowersOfTenMinExp10][1]
	if q < 0 {