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int.go
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int.go
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// Copyright (c) 2022 Gobalsky Labs Limited
//
// Use of this software is governed by the Business Source License included
// in the LICENSE.ZETA file and at https://www.mariadb.com/bsl11.
//
// Change Date: 18 months from the later of the date of the first publicly
// available Distribution of this version of the repository, and 25 June 2022.
//
// On the date above, in accordance with the Business Source License, use
// of this software will be governed by version 3 or later of the GNU General
// Public License.
package num
import (
"math/big"
"github.com/holiman/uint256"
)
var intZero = NewInt(0)
// Int a wrapper to a signed big int.
type Int struct {
// The unsigned version of the integer
U *Uint
// The sign of the integer true = positive, false = negative
s bool
}
func IntFromUint(u *Uint, s bool) *Int {
return &Int{
s: s,
U: u.Clone(),
}
}
func IntToString(u *Int) string {
if u != nil {
return u.String()
}
return "0"
}
// IntFromString creates a new Int from a string
// interpreted using the give base.
// A big.Int is used to read the string, so
// all error related to big.Int parsing applied here.
// will return true if an error happened.
func IntFromString(str string, base int) (*Int, bool) {
b, ok := big.NewInt(0).SetString(str, base)
if !ok {
return NewInt(0), true
}
return IntFromBig(b)
}
// IntFromBig construct a new Int with a big.Int
// returns true if overflow happened.
func IntFromBig(b *big.Int) (*Int, bool) {
positive := true
if b.Sign() < 0 {
b.Neg(b)
positive = false
}
u, overflow := uint256.FromBig(b)
if overflow {
return NewInt(0), true
}
return &Int{
U: &Uint{*u},
s: positive,
}, false
}
// IsNegative tests if the stored value is negative
// true if < 0
// false if >= 0.
func (i *Int) IsNegative() bool {
return !i.s && !i.U.IsZero()
}
// IsPositive tests if the stored value is positive
// true if > 0
// false if <= 0.
func (i *Int) IsPositive() bool {
return i.s && !i.U.IsZero()
}
// IsZero tests if the stored value is zero
// true if == 0.
func (i *Int) IsZero() bool {
return i.U.IsZero()
}
// FlipSign changes the sign of the number from - to + and back again.
func (i *Int) FlipSign() {
i.s = !i.s
}
// Clone creates a copy of the object so nothing is shared.
func (i Int) Clone() *Int {
return &Int{
U: i.U.Clone(),
s: i.s,
}
}
func (i Int) EQ(o *Int) bool {
return i.s == o.s && i.U.EQ(o.U)
}
// GT returns if i > o.
func (i Int) GT(o *Int) bool {
if i.IsNegative() {
if o.IsPositive() || o.IsZero() {
return false
}
return i.U.LT(o.U)
}
if i.IsPositive() {
if o.IsZero() || o.IsNegative() {
return true
}
return i.U.GT(o.U)
}
return o.IsNegative()
}
func (i Int) GTE(o *Int) bool {
return i.GT(o) || i.EQ(o)
}
// LT returns if i < o.
func (i Int) LT(o *Int) bool {
if i.IsNegative() {
if o.IsPositive() || o.IsZero() {
return true
}
return i.U.GT(o.U)
}
if i.IsPositive() {
if o.IsZero() || o.IsNegative() {
return false
}
return i.U.LT(o.U)
}
return o.IsPositive()
}
func (i Int) LTE(o *Int) bool {
return i.LT(o) || i.EQ(o)
}
func (i Int) Int64() int64 {
val := int64(i.U.Uint64())
if i.IsNegative() {
return -val
}
return val
}
// String returns a string version of the number.
func (i Int) String() string {
val := i.U.String()
if i.IsNegative() {
return "-" + val
}
return val
}
// Add will add the passed in value to the base value
// i = i + a.
func (i *Int) Add(a *Int) *Int {
// Handle cases where we have a zero
if a.IsZero() {
return i
}
if i.IsZero() {
i.U.Set(a.U)
i.s = a.s
return i
}
// Handle the easy cases were both are the same sign
if i.IsPositive() && a.IsPositive() {
i.U.Add(i.U, a.U)
return i
}
if i.IsNegative() && a.IsNegative() {
i.U.Add(i.U, a.U)
return i
}
// Now the cases where the signs are different
if i.IsNegative() {
if i.U.GTE(a.U) {
// abs(i) >= a
i.U.Sub(i.U, a.U)
} else {
// abs(i) < a
i.U.Sub(a.U, i.U)
i.s = true
}
return i
}
if i.U.GTE(a.U) {
// i >= abs(a)
i.U.Sub(i.U, a.U)
} else {
// i < abs(a)
i.U.Sub(a.U, i.U)
i.s = false
}
return i
}
// Sub will subtract the passed in value from the base value
// i = i - a.
func (i *Int) Sub(a *Int) *Int {
a.FlipSign()
i.Add(a)
a.FlipSign()
return i
}
// AddSum adds all of the parameters to i
// i = i + a + b + c.
func (i *Int) AddSum(vals ...*Int) *Int {
for _, x := range vals {
i.Add(x)
}
return i
}
// SubSum subtracts all of the parameters from i
// i = i - a - b - c.
func (i *Int) SubSum(vals ...*Int) *Int {
for _, x := range vals {
i.Sub(x)
}
return i
}
// NewInt creates a new Int with the value of the
// int64 passed as a parameter.
func NewInt(val int64) *Int {
if val < 0 {
return &Int{
U: NewUint(uint64(-val)),
s: false,
}
}
return &Int{
U: NewUint(uint64(val)),
s: true,
}
}
func IntZero() *Int {
return intZero.Clone()
}
// NewIntFromUint creates a new Int with the value of the
// uint passed as a parameter.
func NewIntFromUint(val *Uint) *Int {
return &Int{
U: val,
s: true,
}
}