fnv.go 1.2 KB

123456789101112131415161718192021222324252627282930313233343536373839404142
  1. // Copyright 2015 The Prometheus Authors
  2. // Licensed under the Apache License, Version 2.0 (the "License");
  3. // you may not use this file except in compliance with the License.
  4. // You may obtain a copy of the License at
  5. //
  6. // http://www.apache.org/licenses/LICENSE-2.0
  7. //
  8. // Unless required by applicable law or agreed to in writing, software
  9. // distributed under the License is distributed on an "AS IS" BASIS,
  10. // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  11. // See the License for the specific language governing permissions and
  12. // limitations under the License.
  13. package model
  14. // Inline and byte-free variant of hash/fnv's fnv64a.
  15. const (
  16. offset64 = 14695981039346656037
  17. prime64 = 1099511628211
  18. )
  19. // hashNew initializies a new fnv64a hash value.
  20. func hashNew() uint64 {
  21. return offset64
  22. }
  23. // hashAdd adds a string to a fnv64a hash value, returning the updated hash.
  24. func hashAdd(h uint64, s string) uint64 {
  25. for i := 0; i < len(s); i++ {
  26. h ^= uint64(s[i])
  27. h *= prime64
  28. }
  29. return h
  30. }
  31. // hashAddByte adds a byte to a fnv64a hash value, returning the updated hash.
  32. func hashAddByte(h uint64, b byte) uint64 {
  33. h ^= uint64(b)
  34. h *= prime64
  35. return h
  36. }