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common/math: add safe division, modulo, and utility functions
Add new integer utility functions to common/math package: - SafeDiv: safe division that returns error flag on division by zero - SafeMod: safe modulo that returns error flag on modulo by zero - Min: returns minimum of two uint64 values - Max: returns maximum of two uint64 values - Clamp: constrains value to a range [min, max] - AbsDiff: returns absolute difference between two uint64 values These utilities provide commonly needed operations with proper edge case handling, particularly useful for gas calculations and other EVM-related integer operations where division/modulo by zero must be handled gracefully. Includes comprehensive tests for all new functions.
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SmartFlow Developer
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2 changed files with 240 additions and 0 deletions
76
common/math/integer_additions.go
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76
common/math/integer_additions.go
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package math
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// SafeDiv returns x/y and checks for division by zero.
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// Returns (0, true) if y is zero (indicating an error condition).
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// Returns (x/y, false) if the division is valid.
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func SafeDiv(x, y uint64) (uint64, bool) {
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if y == 0 {
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return 0, true
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}
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return x / y, false
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}
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// SafeMod returns x%y and checks for division by zero.
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// Returns (0, true) if y is zero (indicating an error condition).
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// Returns (x%y, false) if the operation is valid.
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func SafeMod(x, y uint64) (uint64, bool) {
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if y == 0 {
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return 0, true
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}
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return x % y, false
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}
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// Min returns the smaller of x or y.
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func Min(x, y uint64) uint64 {
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if x < y {
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return x
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}
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return y
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}
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// Max returns the larger of x or y.
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func Max(x, y uint64) uint64 {
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if x > y {
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return x
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}
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return y
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}
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// Clamp returns x clamped to the inclusive range [min, max].
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// If x is less than min, min is returned.
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// If x is greater than max, max is returned.
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// Otherwise, x is returned unchanged.
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func Clamp(x, min, max uint64) uint64 {
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if x < min {
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return min
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}
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if x > max {
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return max
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}
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return x
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}
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// AbsDiff returns the absolute difference between x and y.
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// This is useful when you need |x - y| without worrying about underflow.
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func AbsDiff(x, y uint64) uint64 {
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if x > y {
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return x - y
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}
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return y - x
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}
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164
common/math/integer_additions_test.go
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164
common/math/integer_additions_test.go
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package math
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import (
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"math"
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"testing"
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)
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func TestSafeDiv(t *testing.T) {
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tests := []struct {
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x, y uint64
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expected uint64
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isError bool
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}{
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{10, 2, 5, false},
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{10, 3, 3, false},
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{0, 5, 0, false},
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{100, 1, 100, false},
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{math.MaxUint64, 2, math.MaxUint64 / 2, false},
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// Division by zero cases
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{10, 0, 0, true},
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{0, 0, 0, true},
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{math.MaxUint64, 0, 0, true},
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}
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for i, test := range tests {
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result, isError := SafeDiv(test.x, test.y)
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if isError != test.isError {
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t.Errorf("test %d: SafeDiv(%d, %d) error = %v, want %v", i, test.x, test.y, isError, test.isError)
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}
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if !isError && result != test.expected {
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t.Errorf("test %d: SafeDiv(%d, %d) = %d, want %d", i, test.x, test.y, result, test.expected)
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}
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}
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}
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func TestSafeMod(t *testing.T) {
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tests := []struct {
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x, y uint64
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expected uint64
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isError bool
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}{
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{10, 3, 1, false},
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{10, 2, 0, false},
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{0, 5, 0, false},
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{7, 7, 0, false},
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{math.MaxUint64, 2, 1, false},
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// Modulo by zero cases
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{10, 0, 0, true},
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{0, 0, 0, true},
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}
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for i, test := range tests {
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result, isError := SafeMod(test.x, test.y)
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if isError != test.isError {
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t.Errorf("test %d: SafeMod(%d, %d) error = %v, want %v", i, test.x, test.y, isError, test.isError)
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}
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if !isError && result != test.expected {
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t.Errorf("test %d: SafeMod(%d, %d) = %d, want %d", i, test.x, test.y, result, test.expected)
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}
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}
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}
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func TestMin(t *testing.T) {
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tests := []struct {
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x, y uint64
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expected uint64
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}{
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{1, 2, 1},
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{2, 1, 1},
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{5, 5, 5},
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{0, 100, 0},
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{math.MaxUint64, 0, 0},
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{math.MaxUint64, math.MaxUint64 - 1, math.MaxUint64 - 1},
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}
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for i, test := range tests {
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result := Min(test.x, test.y)
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if result != test.expected {
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t.Errorf("test %d: Min(%d, %d) = %d, want %d", i, test.x, test.y, result, test.expected)
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}
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}
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}
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func TestMax(t *testing.T) {
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tests := []struct {
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x, y uint64
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expected uint64
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}{
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{1, 2, 2},
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{2, 1, 2},
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{5, 5, 5},
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{0, 100, 100},
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{math.MaxUint64, 0, math.MaxUint64},
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{math.MaxUint64, math.MaxUint64 - 1, math.MaxUint64},
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}
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for i, test := range tests {
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result := Max(test.x, test.y)
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if result != test.expected {
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t.Errorf("test %d: Max(%d, %d) = %d, want %d", i, test.x, test.y, result, test.expected)
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}
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}
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}
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func TestClamp(t *testing.T) {
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tests := []struct {
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x, min, max uint64
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expected uint64
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}{
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{5, 0, 10, 5}, // within range
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{0, 5, 10, 5}, // below min
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{15, 5, 10, 10}, // above max
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{5, 5, 10, 5}, // at min
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{10, 5, 10, 10}, // at max
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{5, 5, 5, 5}, // min == max == x
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{0, 0, 0, 0}, // all zero
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{100, 0, 50, 50}, // clamped to max
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}
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for i, test := range tests {
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result := Clamp(test.x, test.min, test.max)
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if result != test.expected {
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t.Errorf("test %d: Clamp(%d, %d, %d) = %d, want %d", i, test.x, test.min, test.max, result, test.expected)
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}
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}
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}
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func TestAbsDiff(t *testing.T) {
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tests := []struct {
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x, y uint64
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expected uint64
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}{
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{10, 3, 7},
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{3, 10, 7},
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{5, 5, 0},
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{0, 0, 0},
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{math.MaxUint64, 0, math.MaxUint64},
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{0, math.MaxUint64, math.MaxUint64},
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{100, 99, 1},
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}
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for i, test := range tests {
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result := AbsDiff(test.x, test.y)
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if result != test.expected {
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t.Errorf("test %d: AbsDiff(%d, %d) = %d, want %d", i, test.x, test.y, result, test.expected)
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}
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}
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}
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