github.com/amazechain/amc@v0.1.3/common/math/integer.go (about)

     1  // Copyright 2023 The AmazeChain Authors
     2  // This file is part of the AmazeChain library.
     3  //
     4  // The AmazeChain library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The AmazeChain library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the AmazeChain library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package math
    18  
    19  import (
    20  	"crypto/rand"
    21  	"fmt"
    22  	"math"
    23  	"math/big"
    24  	"math/bits"
    25  	"strconv"
    26  )
    27  
    28  // Integer limit values.
    29  const (
    30  	MaxInt8   = 1<<7 - 1
    31  	MinInt8   = -1 << 7
    32  	MaxInt16  = 1<<15 - 1
    33  	MinInt16  = -1 << 15
    34  	MaxInt32  = 1<<31 - 1
    35  	MinInt32  = -1 << 31
    36  	MaxInt64  = 1<<63 - 1
    37  	MinInt64  = -1 << 63
    38  	MaxUint8  = 1<<8 - 1
    39  	MaxUint16 = 1<<16 - 1
    40  	MaxUint32 = 1<<32 - 1
    41  	MaxUint64 = 1<<64 - 1
    42  )
    43  
    44  // HexOrDecimal64 marshals uint64 as hex or decimal.
    45  type HexOrDecimal64 uint64
    46  
    47  // UnmarshalText implements encoding.TextUnmarshaler.
    48  func (i *HexOrDecimal64) UnmarshalText(input []byte) error {
    49  	int, ok := ParseUint64(string(input))
    50  	if !ok {
    51  		return fmt.Errorf("invalid hex or decimal integer %q", input)
    52  	}
    53  	*i = HexOrDecimal64(int)
    54  	return nil
    55  }
    56  
    57  // MarshalText implements encoding.TextMarshaler.
    58  func (i HexOrDecimal64) MarshalText() ([]byte, error) {
    59  	return []byte(fmt.Sprintf("%#x", uint64(i))), nil
    60  }
    61  
    62  // ParseUint64 parses s as an integer in decimal or hexadecimal syntax.
    63  // Leading zeros are accepted. The empty string parses as zero.
    64  func ParseUint64(s string) (uint64, bool) {
    65  	if s == "" {
    66  		return 0, true
    67  	}
    68  	if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") {
    69  		v, err := strconv.ParseUint(s[2:], 16, 64)
    70  		return v, err == nil
    71  	}
    72  	v, err := strconv.ParseUint(s, 10, 64)
    73  	return v, err == nil
    74  }
    75  
    76  // MustParseUint64 parses s as an integer and panics if the string is invalid.
    77  func MustParseUint64(s string) uint64 {
    78  	v, ok := ParseUint64(s)
    79  	if !ok {
    80  		panic("invalid unsigned 64 bit integer: " + s)
    81  	}
    82  	return v
    83  }
    84  
    85  // SafeSub returns x-y and checks for overflow.
    86  func SafeSub(x, y uint64) (uint64, bool) {
    87  	diff, borrowOut := bits.Sub64(x, y, 0)
    88  	return diff, borrowOut != 0
    89  }
    90  
    91  // SafeAdd returns x+y and checks for overflow.
    92  func SafeAdd(x, y uint64) (uint64, bool) {
    93  	sum, carryOut := bits.Add64(x, y, 0)
    94  	return sum, carryOut != 0
    95  }
    96  
    97  // SafeMul returns x*y and checks for overflow.
    98  func SafeMul(x, y uint64) (uint64, bool) {
    99  	hi, lo := bits.Mul64(x, y)
   100  	return lo, hi != 0
   101  }
   102  
   103  // AbsoluteDifference is a utility method that given 2 int64, it returns the absolute value of their difference in uint64 format.
   104  func AbsoluteDifference(x, y uint64) uint64 {
   105  	if x > y {
   106  		return x - y
   107  	}
   108  	return y - x
   109  }
   110  
   111  func RandInt64() (int64, error) {
   112  	n, err := rand.Int(rand.Reader, big.NewInt(math.MaxInt64))
   113  	if err != nil {
   114  		return 0, err
   115  	}
   116  	return n.Int64(), nil
   117  }