/*
 *  Baltisot
 *  Copyright (C) 1999-2008 Nicolas "Pixel" Noble
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* $Id: RandISAAC.cc,v 1.1 2008-07-18 14:01:49 pixel Exp $ */

/* Based on ISAAC. See original (C) mention below. */

/*
------------------------------------------------------------------------------
rand.c: By Bob Jenkins.  My random number generator, ISAAC.  Public Domain
MODIFIED:
  960327: Creation (addition of randinit, really)
  970719: use context, not global variables, for internal state
  980324: make a portable version
  010626: Note this is public domain
------------------------------------------------------------------------------
*/

#include <stdio.h>

#include <RandISAAC.h>

#define bis(target,mask)  ((target) |=  (mask))
#define bic(target,mask)  ((target) &= ~(mask))
#define bit(target,mask)  ((target) &   (mask))

#ifndef align
# define align(a) (((Uint32)a+(sizeof(void *)-1))&(~(sizeof(void *)-1)))
#endif /* align */

#define ind(mm,x)  ((mm)[(x>>2)&(RANDSIZ-1)])
#define rngstep(mix,a,b,mm,m,m2,r,x) \
{ \
  x = *m;  \
  a = ((a^(mix)) + *(m2++)) & 0xffffffff; \
  *(m++) = y = (ind(mm,x) + a + b) & 0xffffffff; \
  *(r++) = b = (ind(mm,y>>RANDSIZL) + x) & 0xffffffff; \
}

void Random::isaac() {
   Uint32 a,b,x,y,*m,*mm,*m2,*r,*mend;
   mm=randmem; r=randrsl;
   a = randa; b = (randb + (++randc)) & 0xffffffff;
   for (m = mm, mend = m2 = m+(RANDSIZ/2); m<mend; )
   {
      rngstep( a<<13, a, b, mm, m, m2, r, x);
      rngstep( a>>6 , a, b, mm, m, m2, r, x);
      rngstep( a<<2 , a, b, mm, m, m2, r, x);
      rngstep( a>>16, a, b, mm, m, m2, r, x);
   }
   for (m2 = mm; m2<mend; )
   {
      rngstep( a<<13, a, b, mm, m, m2, r, x);
      rngstep( a>>6 , a, b, mm, m, m2, r, x);
      rngstep( a<<2 , a, b, mm, m, m2, r, x);
      rngstep( a>>16, a, b, mm, m, m2, r, x);
   }
   randb = b; randa = a;
}


#define mix(a,b,c,d,e,f,g,h) \
{ \
   a^=b<<11; d+=a; b+=c; \
   b^=c>>2;  e+=b; c+=d; \
   c^=d<<8;  f+=c; d+=e; \
   d^=e>>16; g+=d; e+=f; \
   e^=f<<10; h+=e; f+=g; \
   f^=g>>4;  a+=f; g+=h; \
   g^=h<<8;  b+=g; h+=a; \
   h^=a>>9;  c+=h; a+=b; \
}

/* if (flag==TRUE), then use the contents of randrsl[] to initialize mm[]. */
void Random::randinit(int flag) {
   int i;
   Uint32 a,b,c,d,e,f,g,h;
   Uint32 *m,*r;
   randa = randb = randc = 0;
   m=randmem;
   r=randrsl;
   a=b=c=d=e=f=g=h=0x9e3779b9;  /* the golden ratio */

   for (i=0; i<4; ++i)          /* scramble it */
   {
     mix(a,b,c,d,e,f,g,h);
   }

   if (flag) 
   {
     /* initialize using the contents of r[] as the seed */
     for (i=0; i<RANDSIZ; i+=8)
     {
       a+=r[i  ]; b+=r[i+1]; c+=r[i+2]; d+=r[i+3];
       e+=r[i+4]; f+=r[i+5]; g+=r[i+6]; h+=r[i+7];
       mix(a,b,c,d,e,f,g,h);
       m[i  ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
       m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
     }
     /* do a second pass to make all of the seed affect all of m */
     for (i=0; i<RANDSIZ; i+=8)
     {
       a+=m[i  ]; b+=m[i+1]; c+=m[i+2]; d+=m[i+3];
       e+=m[i+4]; f+=m[i+5]; g+=m[i+6]; h+=m[i+7];
       mix(a,b,c,d,e,f,g,h);
       m[i  ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
       m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
     }
   }
   else
   {
     for (i=0; i<RANDSIZ; i+=8)
     {
       /* fill in mm[] with messy stuff */
       mix(a,b,c,d,e,f,g,h);
       m[i  ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
       m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
     }
   }

   isaac();            /* fill in the first set of results */
   randcnt=RANDSIZ;  /* prepare to use the first set of results */
}

Random::Random() {
    int i;
    
    srand(time(NULL));
    for (i = 0; i < RANDSIZ; i++) {
        randrsl[i] = rand();
    }
    randinit(1);
}

Random::~Random() {
}

Uint32 Random::get() {
    if (!randcnt--) {
        isaac();
        randcnt = RANDSIZ - 1;
    }
    return randrsl[randcnt];
}