// Copyright 2013, Sébastien Paolacci. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.


/*
Package murmur3 implements Austin Appleby's non-cryptographic MurmurHash3.

 Reference implementation:
    http://code.google.com/p/smhasher/wiki/MurmurHash3

 History, characteristics and (legacy) perfs:
    https://sites.google.com/site/murmurhash/
    https://sites.google.com/site/murmurhash/statistics
*/
package murmur3

type bmixer interface {
	bmix(p []byte) (tail []byte)
	Size() (n int)
	reset()
}

type digest struct {
	clen int      // Digested input cumulative length.
	tail []byte   // 0 to Size()-1 bytes view of `buf'.
	buf  [16]byte // Expected (but not required) to be Size() large.
	seed uint32   // Seed for initializing the hash.
	bmixer
}

func ( *digest) () int { return 1 }

func ( *digest) ( []byte) ( int,  error) {
	 = len()
	.clen += 

	if len(.tail) > 0 {
		// Stick back pending bytes.
		 := .Size() - len(.tail) // nfree ∈ [1, d.Size()-1].
		if  < len() {
			// One full block can be formed.
			 := append(.tail, [:]...)
			 = [:]
			_ = .bmix() // No tail.
		} else {
			// Tail's buf is large enough to prevent reallocs.
			 = append(.tail, ...)
		}
	}

	.tail = .bmix()

	// Keep own copy of the 0 to Size()-1 pending bytes.
	 := copy(.buf[:], .tail)
	.tail = .buf[:]

	return , nil
}

func ( *digest) () {
	.clen = 0
	.tail = nil
	.bmixer.reset()
}