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      1 /*	$NetBSD: random.h,v 1.5 2021/12/05 09:22:45 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  * Randomizer; returns a random sequence of values from [0..fx) returning each
     34  * 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 
     42 class 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