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safemath.go
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/
safemath.go
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/*
* Copyright 2019 Insolar Technologies
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package safemath
import (
"errors"
)
// Mul multiplies two uints, error on overflow.
func Mul(a uint, b uint) (uint, error) {
if a == 0 {
return 0, nil
}
c := a * b
if c/a != b {
return 0, errors.New("multiplication overflow")
}
return c, nil
}
// Div is integer division of two uints truncating the quotient, reverts on division by zero.
func Div(a uint, b uint) (uint, error) {
if b == 0 {
return 0, errors.New("divisor cannot be zero")
}
return a / b, nil
}
// Sub subtracts two uints, reverts on overflow (i.e. if subtrahend is greater than minuend).
func Sub(a uint, b uint) (uint, error) {
if a < b {
return 0, errors.New("subtrahend must be smaller than minuend")
}
return a - b, nil
}
// Add adds two uints, reverts on overflow.
func Add(a uint, b uint) (uint, error) {
c := a + b
if c < a {
return 0, errors.New("overflow at addition")
}
return c, nil
}
// Mod divides two uints and returns the remainder (unsigned integer modulo), reverts when dividing by zero.
func Mod(a uint, b uint) (uint, error) {
if b == 0 {
return 0, errors.New("divisor cannot be zero")
}
return a % b, nil
}