github.com/ethersphere/bee/v2@v2.2.0/pkg/bitvector/bitvector.go (about)

     1  // Copyright 2018 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  // Package bitvector provides functionality of a
    18  // simple bit vector implementation.
    19  package bitvector
    20  
    21  import (
    22  	"errors"
    23  )
    24  
    25  var errInvalidLength = errors.New("invalid length")
    26  
    27  // BitVector is a convenience object for manipulating and representing bit vectors
    28  type BitVector struct {
    29  	len int
    30  	b   []byte
    31  }
    32  
    33  // New creates a new bit vector with the given length
    34  func New(l int) (*BitVector, error) {
    35  	return NewFromBytes(make([]byte, l/8+1), l)
    36  }
    37  
    38  // NewFromBytes creates a bit vector from the passed byte slice.
    39  //
    40  // Leftmost bit in byte slice becomes leftmost bit in bit vector
    41  func NewFromBytes(b []byte, l int) (*BitVector, error) {
    42  	if l <= 0 {
    43  		return nil, errInvalidLength
    44  	}
    45  	if len(b)*8 < l {
    46  		return nil, errInvalidLength
    47  	}
    48  	return &BitVector{
    49  		len: l,
    50  		b:   b,
    51  	}, nil
    52  }
    53  
    54  // Get gets the corresponding bit, counted from left to right
    55  func (bv *BitVector) Get(i int) bool {
    56  	bi := i / 8
    57  	return bv.b[bi]&(0x1<<uint(i%8)) != 0
    58  }
    59  
    60  // Set sets the bit corresponding to the index in the bitvector, counted from left to right
    61  func (bv *BitVector) Set(i int) {
    62  	bi := i / 8
    63  	if !bv.Get(i) {
    64  		bv.b[bi] ^= 0x1 << uint8(i%8)
    65  	}
    66  }
    67  
    68  // Bytes retrieves the underlying bytes of the bitvector
    69  func (bv *BitVector) Bytes() []byte {
    70  	return bv.b
    71  }