dab/random.h

   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
  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