mirror of
https://github.com/superseriousbusiness/gotosocial.git
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ed46224573
* Add SQLite support, fix un-thread-safe DB caches, small performance fixes Signed-off-by: kim (grufwub) <grufwub@gmail.com> * add SQLite licenses to README Signed-off-by: kim (grufwub) <grufwub@gmail.com> * appease the linter, and fix my dumbass-ery Signed-off-by: kim (grufwub) <grufwub@gmail.com> * make requested changes Signed-off-by: kim (grufwub) <grufwub@gmail.com> * add back comment Signed-off-by: kim (grufwub) <grufwub@gmail.com>
280 lines
5.8 KiB
Go
280 lines
5.8 KiB
Go
// Copyright (c) 2018 The mathutil Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package mathutil // import "modernc.org/mathutil"
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import (
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"fmt"
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"math"
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"math/big"
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)
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var (
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// MaxInt128 represents the maximun Int128 value as big.Int
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MaxInt128 *big.Int
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// MinInt128 represents the minimun Int128 value as big.Int
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MinInt128 *big.Int
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// MaxUint128 represents the maximun Uint128 value as big.Int
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MaxUint128 *big.Int
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)
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func init() {
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var ok bool
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MaxInt128, ok = big.NewInt(0).SetString("0x7fffffff_ffffffff_ffffffff_ffffffff", 0)
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if !ok {
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panic("internal error")
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}
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MinInt128 = big.NewInt(0).Set(MaxInt128)
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MinInt128.Add(MinInt128, _1)
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MinInt128.Neg(MinInt128)
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MaxUint128, ok = big.NewInt(0).SetString("0xffffffff_ffffffff_ffffffff_ffffffff", 0)
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if !ok {
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panic("internal error")
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}
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}
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const (
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maxInt128 = 1<<127 - 1
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maxUint128 = 1<<128 - 1
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minInt128 = -maxInt128 - 1
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)
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// Int128 is an 128 bit signed integer.
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type Int128 struct {
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Lo int64 // Bits 63..0.
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Hi int64 // Bits 127..64.
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}
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// Add returns the sum of x and y and a carry indication.
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func (x Int128) Add(y Int128) (r Int128, cy bool) {
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r.Lo = x.Lo + y.Lo
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r.Hi = x.Hi + y.Hi
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if uint64(r.Lo) < uint64(x.Lo) {
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r.Hi++
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}
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return r, (r.Cmp(x) < 0) == (y.Sign() >= 0)
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}
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// BigInt returns x in the form of a big.Int.
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func (x Int128) BigInt() *big.Int {
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r := big.NewInt(x.Hi)
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r.Lsh(r, 64)
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lo := big.NewInt(0)
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lo.SetUint64(uint64(x.Lo))
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return r.Add(r, lo)
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}
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// Cmp compares x and y and returns:
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//
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// -1 if x < y
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// 0 if x == y
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// +1 if x > y
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func (x Int128) Cmp(y Int128) int {
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if x.Hi > y.Hi {
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return 1
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}
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if x.Hi < y.Hi {
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return -1
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}
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if uint64(x.Lo) > uint64(y.Lo) {
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return 1
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}
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if uint64(x.Lo) < uint64(y.Lo) {
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return -1
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}
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return 0
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}
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// Neg returns -x and an indication that x was not equal to MinInt128.
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func (x Int128) Neg() (r Int128, ok bool) {
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if x == (Int128{Hi: math.MinInt64}) {
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return x, false
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}
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x.Lo = ^x.Lo
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x.Hi = ^x.Hi
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r, _ = x.Add(Int128{Lo: 1})
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return r, true
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}
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// SetBigInt sets x to y, returns x and an error, if any.
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func (x *Int128) SetBigInt(y *big.Int) (r Int128, err error) {
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if y.Cmp(MaxInt128) > 0 {
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return *x, fmt.Errorf("%T.SetInt: overflow", x)
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}
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if y.Cmp(MinInt128) < 0 {
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return *x, fmt.Errorf("%T.SetInt: underflow", x)
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}
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neg := y.Sign() < 0
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var z big.Int
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z.Set(y)
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if neg {
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z.Neg(&z)
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}
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r.Lo = z.Int64()
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z.Rsh(&z, 64)
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r.Hi = z.Int64()
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if neg {
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r, _ = r.Neg()
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}
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*x = r
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return r, nil
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}
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// SetInt64 sets x to y and returns x.
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func (x *Int128) SetInt64(y int64) (r Int128) {
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r.Lo = y
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if y >= 0 {
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r.Hi = 0
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*x = r
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return r
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}
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r.Hi = -1
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*x = r
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return r
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}
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// SetUint64 sets x to y and returns x.
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func (x *Int128) SetUint64(y uint64) (r Int128) {
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r = Int128{Lo: int64(y)}
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*x = r
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return r
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}
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// Sign returns:
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//
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// -1 if x < 0
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// 0 if x == 0
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// +1 if x > 0
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func (x Int128) Sign() int {
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if x.Hi < 0 {
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return -1
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}
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if x.Hi != 0 || x.Lo != 0 {
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return 1
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}
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return 0
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}
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// String implements fmt.Stringer()
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func (x Int128) String() string { return x.BigInt().String() }
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// NewInt128FromInt64 return a new Int128 value initialized to n.
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func NewInt128FromInt64(n int64) (r Int128) {
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r.Lo = n
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if n < 0 {
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r.Hi = -1
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}
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return r
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}
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// NewInt128FromUint64 return a new Int128 value initialized to n.
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func NewInt128FromUint64(n uint64) (r Int128) { return Int128{Lo: int64(n)} }
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// NewInt128FromFloat32 returns a new Int128 value initialized to n. Result is
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// not specified in n does not represent a number within the range of Int128
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// values.
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func NewInt128FromFloat32(n float32) (r Int128) {
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if n >= minInt128 && n <= maxInt128 {
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if n >= math.MinInt64 && n <= math.MaxInt64 {
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return NewInt128FromInt64(int64(n))
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}
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f := big.NewFloat(float64(n))
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bi, _ := f.Int(nil)
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r.SetBigInt(bi)
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}
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return r
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}
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// NewInt128FromFloat64 returns a new Int128 value initialized to n. Result is
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// not specified in n does not represent a number within the range of Int128
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// values.
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func NewInt128FromFloat64(n float64) (r Int128) {
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if n >= minInt128 && n <= maxInt128 {
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if n >= math.MinInt64 && n <= math.MaxInt64 {
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return NewInt128FromInt64(int64(n))
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}
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f := big.NewFloat(n)
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bi, _ := f.Int(nil)
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r.SetBigInt(bi)
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}
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return r
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}
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// Uint128 is an 128 bit unsigned integer.
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type Uint128 struct {
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Lo uint64 // Bits 63..0.
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Hi uint64 // Bits 127..64.
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}
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// NewUint128FromInt64 return a new Uint128 value initialized to n.
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func NewUint128FromInt64(n int64) (r Uint128) {
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r.Lo = uint64(n)
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if n < 0 {
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r.Hi = ^uint64(0)
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}
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return r
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}
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// NewUint128FromUint64 return a new Uint128 value initialized to n.
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func NewUint128FromUint64(n uint64) (r Uint128) { return Uint128{Lo: n} }
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// NewUint128FromFloat32 returns a new Uint128 value initialized to n. Result is
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// not specified in n does not represent a number within the range of Uint128
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// values.
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func NewUint128FromFloat32(n float32) (r Uint128) {
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if n >= 0 {
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if n <= math.MaxUint64 {
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return NewUint128FromUint64(uint64(n))
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}
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f := big.NewFloat(float64(n))
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bi, _ := f.Int(nil)
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r.SetBigInt(bi)
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}
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return r
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}
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// NewUint128FromFloat64 returns a new Uint128 value initialized to n. Result is
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// not specified in n does not represent a number within the range of Uint128
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// values.
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func NewUint128FromFloat64(n float64) (r Uint128) {
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if n >= 0 && n <= maxUint128 {
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if n <= math.MaxUint64 {
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return NewUint128FromUint64(uint64(n))
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}
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f := big.NewFloat(n)
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bi, _ := f.Int(nil)
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r.SetBigInt(bi)
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}
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return r
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}
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// SetBigInt sets x to y, returns x and an error, if any.
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func (x *Uint128) SetBigInt(y *big.Int) (r Uint128, err error) {
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if y.Sign() < 0 || y.Cmp(MaxUint128) > 0 {
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return *x, fmt.Errorf("%T.SetInt: overflow", x)
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}
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var z big.Int
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z.Set(y)
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r.Lo = z.Uint64()
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z.Rsh(&z, 64)
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r.Hi = z.Uint64()
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*x = r
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return r, nil
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}
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