/*      $NetBSD: random.h,v 1.5 2021/12/05 09:22:45 rillig Exp $        */

/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christos Zoulas.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* Randomizer; returns a random sequence of values from [0..fx) returning each
* value exactly once. After fx calls it returns fx.
*/

#ifndef _H_RANDOM
#define _H_RANDOM

#include <stdlib.h>

class RANDOM {
 public:
   // Constructor and destructor
   RANDOM(size_t fx);
   ~RANDOM();

   size_t operator () (void);  // Next random
   void clear(void);           // Reset

 private:

   int isset(size_t z) {
       return (_bm[z >> 3] & (1 << (z & 7))) != 0;
   }

   void set(size_t z) {
       _bm[z >> 3] |= (1 << (z & 7));
   }

   char*       _bm;    // Bitmap indicating the numbers used
   size_t      _nv;    // Number of values returned so far
   size_t      _bs;    // Maximum value
};

#endif