go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/common/data/cmpbin/binary_tools.go (about)

     1  // Copyright 2015 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package cmpbin
    16  
    17  import (
    18  	"bytes"
    19  )
    20  
    21  // ConcatBytes is a convenience invocation of bytes.Join(itms, nil)
    22  func ConcatBytes(itms ...[]byte) []byte {
    23  	return bytes.Join(itms, nil)
    24  }
    25  
    26  // InvertBytes simply inverts all the bytes in bs.
    27  func InvertBytes(bs []byte) []byte {
    28  	if len(bs) == 0 {
    29  		return nil
    30  	}
    31  	ret := make([]byte, len(bs))
    32  	for i, b := range bs {
    33  		ret[i] = 0xFF ^ b
    34  	}
    35  	return ret
    36  }
    37  
    38  // IncrementBytes attempts to increment a copy of bstr as if adding 1 to an integer.
    39  //
    40  // If it overflows, the returned []byte will be all 0's, and the overflow bool
    41  // will be true.
    42  func IncrementBytes(bstr []byte) ([]byte, bool) {
    43  	ret := ConcatBytes(bstr)
    44  	for i := len(ret) - 1; i >= 0; i-- {
    45  		if ret[i] == 0xFF {
    46  			ret[i] = 0
    47  		} else {
    48  			ret[i]++
    49  			return ret, false
    50  		}
    51  	}
    52  	return ret, true
    53  }