555 lines
17 KiB
Go
555 lines
17 KiB
Go
// uint256: Fixed size 256-bit math library
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// Copyright 2020 uint256 Authors
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// SPDX-License-Identifier: BSD-3-Clause
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package uint256
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"math/big"
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"math/bits"
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)
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const (
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maxWords = 256 / bits.UintSize // number of big.Words in 256-bit
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// The constants below work as compile-time checks: in case evaluated to
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// negative value it cannot be assigned to uint type and compilation fails.
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// These particular expressions check if maxWords either 4 or 8 matching
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// 32-bit and 64-bit architectures.
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_ uint = -(maxWords & (maxWords - 1)) // maxWords is power of two.
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_ uint = -(maxWords & ^(4 | 8)) // maxWords is 4 or 8.
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)
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// ToBig returns a big.Int version of z.
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func (z *Int) ToBig() *big.Int {
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b := new(big.Int)
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switch maxWords { // Compile-time check.
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case 4: // 64-bit architectures.
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words := [4]big.Word{big.Word(z[0]), big.Word(z[1]), big.Word(z[2]), big.Word(z[3])}
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b.SetBits(words[:])
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case 8: // 32-bit architectures.
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words := [8]big.Word{
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big.Word(z[0]), big.Word(z[0] >> 32),
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big.Word(z[1]), big.Word(z[1] >> 32),
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big.Word(z[2]), big.Word(z[2] >> 32),
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big.Word(z[3]), big.Word(z[3] >> 32),
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}
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b.SetBits(words[:])
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}
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return b
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}
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// FromBig is a convenience-constructor from big.Int.
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// Returns a new Int and whether overflow occurred.
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func FromBig(b *big.Int) (*Int, bool) {
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z := &Int{}
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overflow := z.SetFromBig(b)
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return z, overflow
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}
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// fromHex is the internal implementation of parsing a hex-string.
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func (z *Int) fromHex(hex string) error {
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if err := checkNumberS(hex); err != nil {
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return err
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}
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if len(hex) > 66 {
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return ErrBig256Range
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}
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end := len(hex)
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for i := 0; i < 4; i++ {
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start := end - 16
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if start < 2 {
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start = 2
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}
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for ri := start; ri < end; ri++ {
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nib := bintable[hex[ri]]
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if nib == badNibble {
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return ErrSyntax
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}
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z[i] = z[i] << 4
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z[i] += uint64(nib)
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}
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end = start
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}
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return nil
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}
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// FromHex is a convenience-constructor to create an Int from
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// a hexadecimal string. The string is required to be '0x'-prefixed
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// Numbers larger than 256 bits are not accepted.
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func FromHex(hex string) (*Int, error) {
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var z Int
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if err := z.fromHex(hex); err != nil {
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return nil, err
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}
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return &z, nil
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}
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// UnmarshalText implements encoding.TextUnmarshaler
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func (z *Int) UnmarshalText(input []byte) error {
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return z.fromHex(string(input))
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}
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// SetFromBig converts a big.Int to Int and sets the value to z.
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// TODO: Ensure we have sufficient testing, esp for negative bigints.
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func (z *Int) SetFromBig(b *big.Int) bool {
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z.Clear()
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words := b.Bits()
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overflow := len(words) > maxWords
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switch maxWords { // Compile-time check.
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case 4: // 64-bit architectures.
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if len(words) > 0 {
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z[0] = uint64(words[0])
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if len(words) > 1 {
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z[1] = uint64(words[1])
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if len(words) > 2 {
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z[2] = uint64(words[2])
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if len(words) > 3 {
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z[3] = uint64(words[3])
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}
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}
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}
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}
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case 8: // 32-bit architectures.
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numWords := len(words)
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if overflow {
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numWords = maxWords
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}
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for i := 0; i < numWords; i++ {
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if i%2 == 0 {
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z[i/2] = uint64(words[i])
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} else {
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z[i/2] |= uint64(words[i]) << 32
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}
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}
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}
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if b.Sign() == -1 {
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z.Neg(z)
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}
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return overflow
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}
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// Format implements fmt.Formatter. It accepts the formats
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// 'b' (binary), 'o' (octal with 0 prefix), 'O' (octal with 0o prefix),
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// 'd' (decimal), 'x' (lowercase hexadecimal), and
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// 'X' (uppercase hexadecimal).
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// Also supported are the full suite of package fmt's format
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// flags for integral types, including '+' and ' ' for sign
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// control, '#' for leading zero in octal and for hexadecimal,
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// a leading "0x" or "0X" for "%#x" and "%#X" respectively,
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// specification of minimum digits precision, output field
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// width, space or zero padding, and '-' for left or right
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// justification.
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//
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func (z *Int) Format(s fmt.State, ch rune) {
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z.ToBig().Format(s, ch)
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}
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// SetBytes8 is identical to SetBytes(in[:8]), but panics is input is too short
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func (z *Int) SetBytes8(in []byte) *Int {
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_ = in[7] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = binary.BigEndian.Uint64(in[0:8])
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return z
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}
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// SetBytes16 is identical to SetBytes(in[:16]), but panics is input is too short
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func (z *Int) SetBytes16(in []byte) *Int {
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_ = in[15] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = binary.BigEndian.Uint64(in[0:8])
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z[0] = binary.BigEndian.Uint64(in[8:16])
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return z
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}
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// SetBytes16 is identical to SetBytes(in[:24]), but panics is input is too short
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func (z *Int) SetBytes24(in []byte) *Int {
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_ = in[23] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = binary.BigEndian.Uint64(in[0:8])
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z[1] = binary.BigEndian.Uint64(in[8:16])
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z[0] = binary.BigEndian.Uint64(in[16:24])
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return z
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}
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func (z *Int) SetBytes32(in []byte) *Int {
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_ = in[31] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = binary.BigEndian.Uint64(in[0:8])
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z[2] = binary.BigEndian.Uint64(in[8:16])
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z[1] = binary.BigEndian.Uint64(in[16:24])
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z[0] = binary.BigEndian.Uint64(in[24:32])
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return z
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}
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func (z *Int) SetBytes1(in []byte) *Int {
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = uint64(in[0])
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return z
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}
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func (z *Int) SetBytes9(in []byte) *Int {
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_ = in[8] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = uint64(in[0])
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z[0] = binary.BigEndian.Uint64(in[1:9])
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return z
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}
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func (z *Int) SetBytes17(in []byte) *Int {
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_ = in[16] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = uint64(in[0])
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z[1] = binary.BigEndian.Uint64(in[1:9])
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z[0] = binary.BigEndian.Uint64(in[9:17])
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return z
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}
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func (z *Int) SetBytes25(in []byte) *Int {
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_ = in[24] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = uint64(in[0])
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z[2] = binary.BigEndian.Uint64(in[1:9])
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z[1] = binary.BigEndian.Uint64(in[9:17])
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z[0] = binary.BigEndian.Uint64(in[17:25])
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return z
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}
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func (z *Int) SetBytes2(in []byte) *Int {
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_ = in[1] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = uint64(binary.BigEndian.Uint16(in[0:2]))
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return z
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}
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func (z *Int) SetBytes10(in []byte) *Int {
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_ = in[9] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = uint64(binary.BigEndian.Uint16(in[0:2]))
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z[0] = binary.BigEndian.Uint64(in[2:10])
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return z
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}
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func (z *Int) SetBytes18(in []byte) *Int {
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_ = in[17] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = uint64(binary.BigEndian.Uint16(in[0:2]))
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z[1] = binary.BigEndian.Uint64(in[2:10])
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z[0] = binary.BigEndian.Uint64(in[10:18])
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return z
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}
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func (z *Int) SetBytes26(in []byte) *Int {
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_ = in[25] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = uint64(binary.BigEndian.Uint16(in[0:2]))
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z[2] = binary.BigEndian.Uint64(in[2:10])
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z[1] = binary.BigEndian.Uint64(in[10:18])
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z[0] = binary.BigEndian.Uint64(in[18:26])
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return z
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}
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func (z *Int) SetBytes3(in []byte) *Int {
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_ = in[2] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = uint64(binary.BigEndian.Uint16(in[1:3])) | uint64(in[0])<<16
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return z
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}
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func (z *Int) SetBytes11(in []byte) *Int {
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_ = in[10] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = uint64(binary.BigEndian.Uint16(in[1:3])) | uint64(in[0])<<16
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z[0] = binary.BigEndian.Uint64(in[3:11])
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return z
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}
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func (z *Int) SetBytes19(in []byte) *Int {
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_ = in[18] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = uint64(binary.BigEndian.Uint16(in[1:3])) | uint64(in[0])<<16
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z[1] = binary.BigEndian.Uint64(in[3:11])
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z[0] = binary.BigEndian.Uint64(in[11:19])
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return z
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}
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func (z *Int) SetBytes27(in []byte) *Int {
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_ = in[26] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = uint64(binary.BigEndian.Uint16(in[1:3])) | uint64(in[0])<<16
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z[2] = binary.BigEndian.Uint64(in[3:11])
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z[1] = binary.BigEndian.Uint64(in[11:19])
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z[0] = binary.BigEndian.Uint64(in[19:27])
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return z
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}
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func (z *Int) SetBytes4(in []byte) *Int {
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_ = in[3] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = uint64(binary.BigEndian.Uint32(in[0:4]))
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return z
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}
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func (z *Int) SetBytes12(in []byte) *Int {
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_ = in[11] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = uint64(binary.BigEndian.Uint32(in[0:4]))
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z[0] = binary.BigEndian.Uint64(in[4:12])
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return z
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}
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func (z *Int) SetBytes20(in []byte) *Int {
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_ = in[19] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = uint64(binary.BigEndian.Uint32(in[0:4]))
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z[1] = binary.BigEndian.Uint64(in[4:12])
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z[0] = binary.BigEndian.Uint64(in[12:20])
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return z
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}
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func (z *Int) SetBytes28(in []byte) *Int {
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_ = in[27] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = uint64(binary.BigEndian.Uint32(in[0:4]))
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z[2] = binary.BigEndian.Uint64(in[4:12])
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z[1] = binary.BigEndian.Uint64(in[12:20])
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z[0] = binary.BigEndian.Uint64(in[20:28])
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return z
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}
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func (z *Int) SetBytes5(in []byte) *Int {
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_ = in[4] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = bigEndianUint40(in[0:5])
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return z
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}
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func (z *Int) SetBytes13(in []byte) *Int {
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_ = in[12] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = bigEndianUint40(in[0:5])
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z[0] = binary.BigEndian.Uint64(in[5:13])
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return z
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}
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func (z *Int) SetBytes21(in []byte) *Int {
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_ = in[20] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = bigEndianUint40(in[0:5])
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z[1] = binary.BigEndian.Uint64(in[5:13])
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z[0] = binary.BigEndian.Uint64(in[13:21])
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return z
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}
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func (z *Int) SetBytes29(in []byte) *Int {
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_ = in[23] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = bigEndianUint40(in[0:5])
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z[2] = binary.BigEndian.Uint64(in[5:13])
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z[1] = binary.BigEndian.Uint64(in[13:21])
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z[0] = binary.BigEndian.Uint64(in[21:29])
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return z
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}
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func (z *Int) SetBytes6(in []byte) *Int {
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_ = in[5] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = bigEndianUint48(in[0:6])
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return z
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}
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func (z *Int) SetBytes14(in []byte) *Int {
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_ = in[13] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = bigEndianUint48(in[0:6])
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z[0] = binary.BigEndian.Uint64(in[6:14])
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return z
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}
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func (z *Int) SetBytes22(in []byte) *Int {
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_ = in[21] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = bigEndianUint48(in[0:6])
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z[1] = binary.BigEndian.Uint64(in[6:14])
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z[0] = binary.BigEndian.Uint64(in[14:22])
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return z
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}
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func (z *Int) SetBytes30(in []byte) *Int {
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_ = in[29] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = bigEndianUint48(in[0:6])
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z[2] = binary.BigEndian.Uint64(in[6:14])
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z[1] = binary.BigEndian.Uint64(in[14:22])
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z[0] = binary.BigEndian.Uint64(in[22:30])
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return z
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}
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func (z *Int) SetBytes7(in []byte) *Int {
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_ = in[6] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2], z[1] = 0, 0, 0
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z[0] = bigEndianUint56(in[0:7])
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return z
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}
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func (z *Int) SetBytes15(in []byte) *Int {
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_ = in[14] // bounds check hint to compiler; see golang.org/issue/14808
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z[3], z[2] = 0, 0
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z[1] = bigEndianUint56(in[0:7])
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z[0] = binary.BigEndian.Uint64(in[7:15])
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return z
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}
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func (z *Int) SetBytes23(in []byte) *Int {
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_ = in[22] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = 0
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z[2] = bigEndianUint56(in[0:7])
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z[1] = binary.BigEndian.Uint64(in[7:15])
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z[0] = binary.BigEndian.Uint64(in[15:23])
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return z
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}
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func (z *Int) SetBytes31(in []byte) *Int {
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_ = in[30] // bounds check hint to compiler; see golang.org/issue/14808
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z[3] = bigEndianUint56(in[0:7])
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z[2] = binary.BigEndian.Uint64(in[7:15])
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z[1] = binary.BigEndian.Uint64(in[15:23])
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z[0] = binary.BigEndian.Uint64(in[23:31])
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return z
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}
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// Utility methods that are "missing" among the bigEndian.UintXX methods.
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func bigEndianUint40(b []byte) uint64 {
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_ = b[4] // bounds check hint to compiler; see golang.org/issue/14808
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return uint64(b[4]) | uint64(b[3])<<8 | uint64(b[2])<<16 | uint64(b[1])<<24 |
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uint64(b[0])<<32
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}
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func bigEndianUint48(b []byte) uint64 {
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_ = b[5] // bounds check hint to compiler; see golang.org/issue/14808
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return uint64(b[5]) | uint64(b[4])<<8 | uint64(b[3])<<16 | uint64(b[2])<<24 |
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uint64(b[1])<<32 | uint64(b[0])<<40
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}
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func bigEndianUint56(b []byte) uint64 {
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_ = b[6] // bounds check hint to compiler; see golang.org/issue/14808
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return uint64(b[6]) | uint64(b[5])<<8 | uint64(b[4])<<16 | uint64(b[3])<<24 |
|
|
uint64(b[2])<<32 | uint64(b[1])<<40 | uint64(b[0])<<48
|
|
}
|
|
|
|
// EncodeRLP implements the rlp.Encoder interface from go-ethereum
|
|
// and writes the RLP encoding of z to w.
|
|
func (z *Int) EncodeRLP(w io.Writer) error {
|
|
if z == nil {
|
|
_, err := w.Write([]byte{0x80})
|
|
return err
|
|
}
|
|
nBits := z.BitLen()
|
|
if nBits == 0 {
|
|
_, err := w.Write([]byte{0x80})
|
|
return err
|
|
}
|
|
if nBits <= 7 {
|
|
_, err := w.Write([]byte{byte(z[0])})
|
|
return err
|
|
}
|
|
nBytes := byte((nBits + 7) / 8)
|
|
var b [33]byte
|
|
binary.BigEndian.PutUint64(b[1:9], z[3])
|
|
binary.BigEndian.PutUint64(b[9:17], z[2])
|
|
binary.BigEndian.PutUint64(b[17:25], z[1])
|
|
binary.BigEndian.PutUint64(b[25:33], z[0])
|
|
b[32-nBytes] = 0x80 + nBytes
|
|
_, err := w.Write(b[32-nBytes:])
|
|
return err
|
|
}
|
|
|
|
// MarshalText implements encoding.TextMarshaler
|
|
func (z *Int) MarshalText() ([]byte, error) {
|
|
return []byte(z.Hex()), nil
|
|
}
|
|
|
|
// UnmarshalJSON implements json.Unmarshaler.
|
|
func (z *Int) UnmarshalJSON(input []byte) error {
|
|
if len(input) < 2 || input[0] != '"' || input[len(input)-1] != '"' {
|
|
return ErrNonString
|
|
}
|
|
return z.UnmarshalText(input[1 : len(input)-1])
|
|
}
|
|
|
|
// String returns the hex encoding of b.
|
|
func (z *Int) String() string {
|
|
return z.Hex()
|
|
}
|
|
|
|
const (
|
|
hextable = "0123456789abcdef"
|
|
bintable = "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x01\x02\x03\x04\x05\x06\a\b\t\xff\xff\xff\xff\xff\xff\xff\n\v\f\r\x0e\x0f\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\n\v\f\r\x0e\x0f\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
|
|
badNibble = 0xff
|
|
)
|
|
|
|
// Hex encodes z in 0x-prefixed hexadecimal form.
|
|
func (z *Int) Hex() string {
|
|
// This implementation is not optimal, it allocates a full
|
|
// 66-byte output buffer which it fills. It could instead allocate a smaller
|
|
// buffer, and omit the final crop-stage.
|
|
output := make([]byte, 66)
|
|
nibbles := (z.BitLen() + 3) / 4 // nibbles [0,64]
|
|
if nibbles == 0 {
|
|
nibbles = 1
|
|
}
|
|
// Start with the most significant
|
|
zWord := (nibbles - 1) / 16
|
|
for i := zWord; i >= 0; i-- {
|
|
off := (3 - i) * 16
|
|
output[off+2] = hextable[byte(z[i]>>60)&0xf]
|
|
output[off+3] = hextable[byte(z[i]>>56)&0xf]
|
|
output[off+4] = hextable[byte(z[i]>>52)&0xf]
|
|
output[off+5] = hextable[byte(z[i]>>48)&0xf]
|
|
output[off+6] = hextable[byte(z[i]>>44)&0xf]
|
|
output[off+7] = hextable[byte(z[i]>>40)&0xf]
|
|
output[off+8] = hextable[byte(z[i]>>36)&0xf]
|
|
output[off+9] = hextable[byte(z[i]>>32)&0xf]
|
|
output[off+10] = hextable[byte(z[i]>>28)&0xf]
|
|
output[off+11] = hextable[byte(z[i]>>24)&0xf]
|
|
output[off+12] = hextable[byte(z[i]>>20)&0xf]
|
|
output[off+13] = hextable[byte(z[i]>>16)&0xf]
|
|
output[off+14] = hextable[byte(z[i]>>12)&0xf]
|
|
output[off+15] = hextable[byte(z[i]>>8)&0xf]
|
|
output[off+16] = hextable[byte(z[i]>>4)&0xf]
|
|
output[off+17] = hextable[byte(z[i]&0xF)&0xf]
|
|
}
|
|
output[64-nibbles] = '0'
|
|
output[65-nibbles] = 'x'
|
|
return string(output[64-nibbles:])
|
|
}
|
|
|
|
var (
|
|
ErrEmptyString = errors.New("empty hex string")
|
|
ErrSyntax = errors.New("invalid hex string")
|
|
ErrMissingPrefix = errors.New("hex string without 0x prefix")
|
|
ErrEmptyNumber = errors.New("hex string \"0x\"")
|
|
ErrLeadingZero = errors.New("hex number with leading zero digits")
|
|
ErrBig256Range = errors.New("hex number > 256 bits")
|
|
ErrNonString = errors.New("non-string")
|
|
)
|
|
|
|
func checkNumberS(input string) error {
|
|
l := len(input)
|
|
if l == 0 {
|
|
return ErrEmptyString
|
|
}
|
|
if l < 2 || input[0] != '0' ||
|
|
(input[1] != 'x' && input[1] != 'X') {
|
|
return ErrMissingPrefix
|
|
}
|
|
if l == 2 {
|
|
return ErrEmptyNumber
|
|
}
|
|
if len(input) > 3 && input[2] == '0' {
|
|
return ErrLeadingZero
|
|
}
|
|
return nil
|
|
}
|