| //go:build !amd64 || appengine || !gc || noasm |
| // +build !amd64 appengine !gc noasm |
| |
| // Copyright 2019+ Klaus Post. All rights reserved. |
| // License information can be found in the LICENSE file. |
| |
| package flate |
| |
| import ( |
| "encoding/binary" |
| "math/bits" |
| ) |
| |
| // matchLen returns the maximum common prefix length of a and b. |
| // a must be the shortest of the two. |
| func matchLen(a, b []byte) (n int) { |
| for ; len(a) >= 8 && len(b) >= 8; a, b = a[8:], b[8:] { |
| diff := binary.LittleEndian.Uint64(a) ^ binary.LittleEndian.Uint64(b) |
| if diff != 0 { |
| return n + bits.TrailingZeros64(diff)>>3 |
| } |
| n += 8 |
| } |
| |
| for i := range a { |
| if a[i] != b[i] { |
| break |
| } |
| n++ |
| } |
| return n |
| |
| } |