Function leftShift

fflib/v1/decimal.go:232–275

Binary shift left (/ 2) by k bits. k <= maxShift to avoid overflow.

(a *decimal, k uint)

// Binary shift left (/ 2) by k bits.  k <= maxShift to avoid overflow.
func leftShift(a *decimal, k uint) {
	delta := leftcheats[k].delta
	if prefixIsLessThan(a.d[0:a.nd], leftcheats[k].cutoff) {
		delta--
	}

	r := a.nd         // read index
	w := a.nd + delta // write index
	n := 0

	// Pick up a digit, put down a digit.
	for r--; r >= 0; r-- {
		n += (int(a.d[r]) - '0') << k
		quo := n / 10
		rem := n - 10*quo
		w--
		if w < len(a.d) {
			a.d[w] = byte(rem + '0')
		} else if rem != 0 {
			a.trunc = true
		}
		n = quo
	}

	// Put down extra digits.
	for n > 0 {
		quo := n / 10
		rem := n - 10*quo
		w--
		if w < len(a.d) {
			a.d[w] = byte(rem + '0')
		} else if rem != 0 {
			a.trunc = true
		}
		n = quo
	}

	a.nd += delta
	if a.nd >= len(a.d) {
		a.nd = len(a.d)
	}
	a.dp += delta
	trim(a)
}

// Binary shift left (k > 0) or right (k < 0).
func (a *decimal) Shift(k int) {