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Using integer operations rather than float in rescale

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This commit is contained in:
Igor Mikushkin 2018-08-29 02:59:01 +04:00
parent cd690d0c9e
commit b836e56a4d
1 changed files with 8 additions and 3 deletions
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11
decimal.go
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@ -361,11 +361,11 @@ func NewFromFloatWithExponent(value float64, exp int32) Decimal {
//
func (d Decimal) rescale(exp int32) Decimal {
d.ensureInitialized()
// NOTE(vadim): must convert exps to float64 before - to prevent overflow
diff := math.Abs(float64(exp) - float64(d.exp))
// NOTE(vadim): must convert exps to int64 before - to prevent overflow
diff := abs64(int64(exp) - int64(d.exp))
value := new(big.Int).Set(d.value)
expScale := new(big.Int).Exp(tenInt, big.NewInt(int64(diff)), nil)
expScale := new(big.Int).Exp(tenInt, big.NewInt(diff), nil)
if exp > d.exp {
value = value.Quo(value, expScale)
} else if exp < d.exp {
@ -378,6 +378,11 @@ func (d Decimal) rescale(exp int32) Decimal {
}
}
func abs64(n int64) int64 {
y := n >> 63
return (n ^ y) - y
}
// Abs returns the absolute value of the decimal.
func (d Decimal) Abs() Decimal {
d.ensureInitialized()