Function adjustLastDigitFixed

fflib/v1/extfloat.go:496–526

adjustLastDigitFixed assumes d contains the representation of the integral part of some number, whose fractional part is num / (den << shift). The numerator num is only known up to an uncertainty of size ε, assumed to be less than (den << shift)/2. It will increase the last digit by one to account

(d *decimalSlice, num, den uint64, shift uint, ε uint64)

// when the fractional part is greater than 1/2, and will return false if ε is such
// that no correct answer can be given.
func adjustLastDigitFixed(d *decimalSlice, num, den uint64, shift uint, ε uint64) bool {
	if num > den<<shift {
		panic("strconv: num > den<<shift in adjustLastDigitFixed")
	}
	if 2*ε > den<<shift {
		panic("strconv: ε > (den<<shift)/2")
	}
	if 2*(num+ε) < den<<shift {
		return true
	}
	if 2*(num-ε) > den<<shift {
		// increment d by 1.
		i := d.nd - 1
		for ; i >= 0; i-- {
			if d.d[i] == '9' {
				d.nd--
			} else {
				break
			}
		}
		if i < 0 {
			d.d[0] = '1'
			d.nd = 1
			d.dp++
		} else {
			d.d[i]++
		}
		return true
	}
	return false
}

// ShortestDecimal stores in d the shortest decimal representation of f
// which belongs to the open interval (lower, upper), where f is supposed