From b2dfbdf4d9644c684c938cb2730deab66aa06d9b Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <lars@6xq.net>
Date: Sat, 2 May 2015 21:36:31 +0200
Subject: Move out of subdir

---
 isaac.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 isaac.c

(limited to 'isaac.c')

diff --git a/isaac.c b/isaac.c
new file mode 100644
index 0000000..014c4d9
--- /dev/null
+++ b/isaac.c
@@ -0,0 +1,110 @@
+/*
+------------------------------------------------------------------------------
+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 */
+}
-- 
cgit v1.2.3