package iskra

import "git.smesh.lol/iskradb/lattice"

const (
	fnvOffset64 uint64 = 14695981039346656037
	fnvPrime64  uint64 = 1099511628211
)

// HashBytes computes 56-bit FNV-1a hash, discarding the top 8 bits.
func HashBytes(data []byte) uint64 {
	h := fnvOffset64
	for _, c := range data {
		h ^= uint64(c)
		h *= fnvPrime64
	}
	return h >> 8
}

// SegmentKey builds a 64-bit key for a segment at a given stage.
func SegmentKey(stage uint8, content []byte) lattice.Key {
	return MakeCodeKey(stage, HashBytes(content))
}