From e98d15d4eb88ec13a6e6ef97e915aada231855fa Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <lars@6xq.net>
Date: Mon, 9 Feb 2015 18:04:22 +0100
Subject: Replace isaac with xorshift

No difference in performance. rdrand instruction alone is too slow.
---
 isaac.c | 110 ----------------------------------------------------------------
 1 file changed, 110 deletions(-)
 delete mode 100644 isaac.c

(limited to 'isaac.c')

diff --git a/isaac.c b/isaac.c
deleted file mode 100644
index 014c4d9..0000000
--- a/isaac.c
+++ /dev/null
@@ -1,110 +0,0 @@
-/*
-------------------------------------------------------------------------------
-isaac.c: By Bob Jenkins.  My random number generator, ISAAC.
-MODIFIED:
-  960327: Creation (addition of randinit, really)
-  970719: use context, not global variables, for internal state
-  980324: make a portable version
-  991209: modified for inclusion with GNU Backgammon by Gary Wong
-  070121: modified for inclusion with flam3 by Erik Reckase
-------------------------------------------------------------------------------
-*/
-
-#include "isaacs.h"
-#include "isaac.h"
-
-#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     isaac(randctx *ctx)
-{
-   register ub4 a,b,x,y,*m,*mm,*m2,*r,*mend;
-   mm=ctx->randmem; r=ctx->randrsl;
-   a = ctx->randa; b = (ctx->randb + (++ctx->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);
-   }
-   ctx->randb = b; ctx->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 irandinit(randctx *ctx, word     flag)
-{
-   word i;
-   ub4 a,b,c,d,e,f,g,h;
-   ub4 *m,*r;
-   ctx->randa = ctx->randb = ctx->randc = 0;
-   m=ctx->randmem;
-   r=ctx->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(ctx);            /* fill in the first set of results */
-   ctx->randcnt=RANDSIZ;  /* prepare to use the first set of results */
-}
-- 
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