github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/util/uint128/uint128.go (about)

     1  // Copyright 2017 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package uint128
    12  
    13  import (
    14  	"encoding/binary"
    15  	"encoding/hex"
    16  
    17  	"github.com/cockroachdb/errors"
    18  )
    19  
    20  // Uint128 is a big-endian 128 bit unsigned integer which wraps two uint64s.
    21  type Uint128 struct {
    22  	Hi, Lo uint64
    23  }
    24  
    25  // GetBytes returns a big-endian byte representation.
    26  func (u Uint128) GetBytes() []byte {
    27  	buf := make([]byte, 16)
    28  	binary.BigEndian.PutUint64(buf[:8], u.Hi)
    29  	binary.BigEndian.PutUint64(buf[8:], u.Lo)
    30  	return buf
    31  }
    32  
    33  // String returns a hexadecimal string representation.
    34  func (u Uint128) String() string {
    35  	return hex.EncodeToString(u.GetBytes())
    36  }
    37  
    38  // Equal returns whether or not the Uint128 are equivalent.
    39  func (u Uint128) Equal(o Uint128) bool {
    40  	return u.Hi == o.Hi && u.Lo == o.Lo
    41  }
    42  
    43  // Compare compares the two Uint128.
    44  func (u Uint128) Compare(o Uint128) int {
    45  	if u.Hi > o.Hi {
    46  		return 1
    47  	} else if u.Hi < o.Hi {
    48  		return -1
    49  	} else if u.Lo > o.Lo {
    50  		return 1
    51  	} else if u.Lo < o.Lo {
    52  		return -1
    53  	}
    54  	return 0
    55  }
    56  
    57  // Add returns a new Uint128 incremented by n.
    58  func (u Uint128) Add(n uint64) Uint128 {
    59  	lo := u.Lo + n
    60  	hi := u.Hi
    61  	if u.Lo > lo {
    62  		hi++
    63  	}
    64  	return Uint128{hi, lo}
    65  }
    66  
    67  // Sub returns a new Uint128 decremented by n.
    68  func (u Uint128) Sub(n uint64) Uint128 {
    69  	lo := u.Lo - n
    70  	hi := u.Hi
    71  	if u.Lo < lo {
    72  		hi--
    73  	}
    74  	return Uint128{hi, lo}
    75  }
    76  
    77  // And returns a new Uint128 that is the bitwise AND of two Uint128 values.
    78  func (u Uint128) And(o Uint128) Uint128 {
    79  	return Uint128{u.Hi & o.Hi, u.Lo & o.Lo}
    80  }
    81  
    82  // Or returns a new Uint128 that is the bitwise OR of two Uint128 values.
    83  func (u Uint128) Or(o Uint128) Uint128 {
    84  	return Uint128{u.Hi | o.Hi, u.Lo | o.Lo}
    85  }
    86  
    87  // Xor returns a new Uint128 that is the bitwise XOR of two Uint128 values.
    88  func (u Uint128) Xor(o Uint128) Uint128 {
    89  	return Uint128{u.Hi ^ o.Hi, u.Lo ^ o.Lo}
    90  }
    91  
    92  // FromBytes parses the byte slice as a 128 bit big-endian unsigned integer.
    93  // The caller is responsible for ensuring the byte slice contains 16 bytes.
    94  func FromBytes(b []byte) Uint128 {
    95  	hi := binary.BigEndian.Uint64(b[:8])
    96  	lo := binary.BigEndian.Uint64(b[8:])
    97  	return Uint128{hi, lo}
    98  }
    99  
   100  // FromString parses a hexadecimal string as a 128-bit big-endian unsigned integer.
   101  func FromString(s string) (Uint128, error) {
   102  	if len(s) > 32 {
   103  		return Uint128{}, errors.Errorf("input string %s too large for uint128", s)
   104  	}
   105  	bytes, err := hex.DecodeString(s)
   106  	if err != nil {
   107  		return Uint128{}, errors.Wrapf(err, "could not decode %s as hex", s)
   108  	}
   109  
   110  	// Grow the byte slice if it's smaller than 16 bytes, by prepending 0s
   111  	if len(bytes) < 16 {
   112  		bytesCopy := make([]byte, 16)
   113  		copy(bytesCopy[(16-len(bytes)):], bytes)
   114  		bytes = bytesCopy
   115  	}
   116  
   117  	return FromBytes(bytes), nil
   118  }
   119  
   120  // FromInts takes in two unsigned 64-bit integers and constructs a Uint128.
   121  func FromInts(hi uint64, lo uint64) Uint128 {
   122  	return Uint128{hi, lo}
   123  }