diff options
Diffstat (limited to 'search/hash.go')
| -rw-r--r-- | search/hash.go | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/search/hash.go b/search/hash.go index 0b41b6b..7302d1a 100644 --- a/search/hash.go +++ b/search/hash.go @@ -26,7 +26,14 @@ func (h *Hash[K,V]) Size() int { } func (h *Hash[K,V]) hash(key K) int { - i := key + key*2 + key<<10 + key>>2 + // Mix the key in a full-width int64 rather than in K. K is any ds.Integer, + // so for a narrow type (e.g. int8) the "key<<10" term would shift past the + // type width and vanish to 0, destroying the intended high-bit mixing (and + // go vet rightly flags it). Widening to int64 first keeps the result + // identical for 64-bit int keys while making the mix well-defined for every + // integer width. + i := int64(key) + i = i + i*2 + i<<10 + i>>2 if i < 0 { i = -i } |