func (z *Big) quoBig(x, y *Big) *Big {
scale, ok := checked.Sub32(x.scale, y.scale)
if !ok {
z.form = inf
return z
}
zp := z.ctx.prec()
xp := int32(x.Prec())
yp := int32(y.Prec())
// Multiply y by 10 if x' > y'
if cmpNormBig(&x.mantissa, xp, &y.mantissa, yp) {
yp--
}
scale, ok = checked.Int32(int64(scale) + int64(yp) - int64(xp) + int64(zp))
if !ok {
z.form = inf
return z
}
z.scale = scale
shift, ok := checked.SumSub(zp, yp, xp)
if !ok {
z.form = inf
return z
}
if shift > 0 {
xs := checked.MulBigPow10(new(big.Int).Set(&x.mantissa), shift)
return z.quoBigAndRound(xs, &y.mantissa)
}
// shift < 0
ns, ok := checked.Sub32(xp, zp)
if !ok {
z.form = inf
return z
}
shift, ok = checked.Sub32(ns, yp)
if !ok {
z.form = inf
return z
}
ys := checked.MulBigPow10(new(big.Int).Set(&y.mantissa), shift)
return z.quoBigAndRound(&x.mantissa, ys)
}
func shiftRadixRight(x *Big, n int) bool {
ns, ok := checked.Sub32(x.Scale(), int32(n))
if !ok {
return false
}
x.SetScale(ns)
return true
}
func (z *Big) quoCompact(x, y *Big) *Big {
if x.compact == 0 {
if y.compact == 0 {
panic(ErrNaN{"division of zero by zero"})
}
z.form = 0
return z
}
scale, ok := checked.Sub32(x.scale, y.scale)
if !ok {
z.form = inf
return z
}
zp := z.ctx.prec()
xp := int32(x.Prec())
yp := int32(y.Prec())
// Multiply y by 10 if x' > y'
if cmpNorm(x.compact, xp, y.compact, yp) {
yp--
}
scale, ok = checked.Int32(int64(scale) + int64(yp) - int64(xp) + int64(zp))
if !ok {
z.form = inf
return z
}
z.scale = scale
shift, ok := checked.SumSub(zp, yp, xp)
if !ok {
z.form = inf
return z
}
xs, ys := x.compact, y.compact
if shift > 0 {
xs, ok = checked.MulPow10(x.compact, shift)
if !ok {
x0 := checked.MulBigPow10(big.NewInt(x.compact), shift)
return z.quoBigAndRound(x0, big.NewInt(y.compact))
}
return z.quoAndRound(xs, ys)
}
// shift < 0
ns, ok := checked.Sub32(xp, zp)
if !ok {
z.form = inf
return z
}
// new scale == yp, so no inflation needed.
if ns == yp {
return z.quoAndRound(xs, ys)
}
shift, ok = checked.Sub32(ns, yp)
if !ok {
z.form = inf
return z
}
ys, ok = checked.MulPow10(ys, shift)
if !ok {
y0 := checked.MulBigPow10(big.NewInt(y.compact), shift)
return z.quoBigAndRound(big.NewInt(x.compact), y0)
}
return z.quoAndRound(xs, ys)
}
