Source file src/github.com/klauspost/compress/flate/matchlen_generic.go

Documentation: github.com/klauspost/compress/flate

     1  //go:build !amd64 || appengine || !gc || noasm
     2  // +build !amd64 appengine !gc noasm
     3  
     4  // Copyright 2019+ Klaus Post. All rights reserved.
     5  // License information can be found in the LICENSE file.
     6  
     7  package flate
     8  
     9  import (
    10  	"encoding/binary"
    11  	"math/bits"
    12  )
    13  
    14  // matchLen returns the maximum common prefix length of a and b.
    15  // a must be the shortest of the two.
    16  func matchLen(a, b []byte) (n int) {
    17  	for ; len(a) >= 8 && len(b) >= 8; a, b = a[8:], b[8:] {
    18  		diff := binary.LittleEndian.Uint64(a) ^ binary.LittleEndian.Uint64(b)
    19  		if diff != 0 {
    20  			return n + bits.TrailingZeros64(diff)>>3
    21  		}
    22  		n += 8
    23  	}
    24  
    25  	for i := range a {
    26  		if a[i] != b[i] {
    27  			break
    28  		}
    29  		n++
    30  	}
    31  	return n
    32  
    33  }
    34  

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