package main

// This file contains functions that are also used by the runtime. These must be
// kept in sync.

// Get FNV-1a hash of this string.
//
// https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
func stringhash(s *string) uint32 {
	var result uint32 = 2166136261 // FNV offset basis
	for i := 0; i < len(*s); i++ {
		result ^= uint32((*s)[i])
		result *= 16777619 // FNV prime
	}
	return result
}

// Get the topmost 8 bits of the hash, without using a special value (like 0).
func hashmapTopHash(hash uint32) uint8 {
	tophash := uint8(hash >> 24)
	if tophash < 1 {
		// 0 means empty slot, so make it bigger.
		tophash += 1
	}
	return tophash
}