| Abhay Kumar | a2ae599 | 2025-11-10 14:02:24 +0000 | [diff] [blame^] | 1 | // Copyright 2019+ Klaus Post. All rights reserved. |
| 2 | // License information can be found in the LICENSE file. |
| 3 | |
| 4 | package flate |
| 5 | |
| 6 | import ( |
| 7 | "math/bits" |
| 8 | |
| 9 | "github.com/klauspost/compress/internal/le" |
| 10 | ) |
| 11 | |
| 12 | // matchLen returns the maximum common prefix length of a and b. |
| 13 | // a must be the shortest of the two. |
| 14 | func matchLen(a, b []byte) (n int) { |
| 15 | left := len(a) |
| 16 | for left >= 8 { |
| 17 | diff := le.Load64(a, n) ^ le.Load64(b, n) |
| 18 | if diff != 0 { |
| 19 | return n + bits.TrailingZeros64(diff)>>3 |
| 20 | } |
| 21 | n += 8 |
| 22 | left -= 8 |
| 23 | } |
| 24 | |
| 25 | a = a[n:] |
| 26 | b = b[n:] |
| 27 | for i := range a { |
| 28 | if a[i] != b[i] { |
| 29 | break |
| 30 | } |
| 31 | n++ |
| 32 | } |
| 33 | return n |
| 34 | } |