random.h revision 1.4 
1/*	$NetBSD: random.h,v 1.4 2021/05/02 12:50:44 rillig Exp $	*/
2
3/*-
4 * Copyright (c) 2003 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * random.h: Randomizer; returns a random sequence of values from [0..fx)
34 *	     returning each value exactly once. After fx calls it returns fx.
35 */
36
37#ifndef _H_RANDOM
38#define _H_RANDOM
39
40#include <stdlib.h>
41
42class RANDOM {
43  public:
44    // Constructor and destructor
45    RANDOM(size_t fx);
46    ~RANDOM();
47
48    size_t operator () (void);	// Next random
49    void clear(void);		// Reset
50
51  private:
52
53    int isset(size_t z) {
54	return (_bm[z >> 3] & (1 << (z & 7))) != 0;
55    }
56
57    void set(size_t z) {
58	_bm[z >> 3] |= (1 << (z & 7));
59    }
60
61    char*	_bm;	// Bitmap indicating the numbers used
62    size_t	_nv;	// Number of values returned so far
63    size_t	_bs;	// Maximum value
64};
65
66#endif
67