2 ------------------------------------------------------------------------------
3 rand.c: By Bob Jenkins. My random number generator, ISAAC. Public Domain
5 960327: Creation (addition of randinit, really)
6 970719: use context, not global variables, for internal state
7 980324: make a portable version
8 010626: Note this is public domain
9 ------------------------------------------------------------------------------
19 #define ind(mm,x) ((mm)[(x>>2)&(RANDSIZ-1)])
20 #define rngstep(mix,a,b,mm,m,m2,r,x) \
23 a = ((a^(mix)) + *(m2++)) & 0xffffffff; \
24 *(m++) = y = (ind(mm,x) + a + b) & 0xffffffff; \
25 *(r++) = b = (ind(mm,y>>RANDSIZL) + x) & 0xffffffff; \
28 void isaac(randctx *ctx)
30 register ub4 a,b,x,y,*m,*mm,*m2,*r,*mend;
31 mm=ctx->randmem; r=ctx->randrsl;
32 a = ctx->randa; b = (ctx->randb + (++ctx->randc)) & 0xffffffff;
33 for (m = mm, mend = m2 = m+(RANDSIZ/2); m<mend; )
35 rngstep( a<<13, a, b, mm, m, m2, r, x);
36 rngstep( a>>6 , a, b, mm, m, m2, r, x);
37 rngstep( a<<2 , a, b, mm, m, m2, r, x);
38 rngstep( a>>16, a, b, mm, m, m2, r, x);
40 for (m2 = mm; m2<mend; )
42 rngstep( a<<13, a, b, mm, m, m2, r, x);
43 rngstep( a>>6 , a, b, mm, m, m2, r, x);
44 rngstep( a<<2 , a, b, mm, m, m2, r, x);
45 rngstep( a>>16, a, b, mm, m, m2, r, x);
47 ctx->randb = b; ctx->randa = a;
51 #define mix(a,b,c,d,e,f,g,h) \
53 a^=b<<11; d+=a; b+=c; \
54 b^=c>>2; e+=b; c+=d; \
55 c^=d<<8; f+=c; d+=e; \
56 d^=e>>16; g+=d; e+=f; \
57 e^=f<<10; h+=e; f+=g; \
58 f^=g>>4; a+=f; g+=h; \
59 g^=h<<8; b+=g; h+=a; \
60 h^=a>>9; c+=h; a+=b; \
63 /* if (flag==TRUE), then use the contents of randrsl[] to initialize mm[]. */
64 void randinit(randctx *ctx, word flag)
69 ctx->randa = ctx->randb = ctx->randc = 0;
72 a=b=c=d=e=f=g=h=0x9e3779b9; /* the golden ratio */
74 for (i=0; i<4; ++i) /* scramble it */
81 /* initialize using the contents of r[] as the seed */
82 for (i=0; i<RANDSIZ; i+=8)
84 a+=r[i ]; b+=r[i+1]; c+=r[i+2]; d+=r[i+3];
85 e+=r[i+4]; f+=r[i+5]; g+=r[i+6]; h+=r[i+7];
87 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
88 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
90 /* do a second pass to make all of the seed affect all of m */
91 for (i=0; i<RANDSIZ; i+=8)
93 a+=m[i ]; b+=m[i+1]; c+=m[i+2]; d+=m[i+3];
94 e+=m[i+4]; f+=m[i+5]; g+=m[i+6]; h+=m[i+7];
96 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
97 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
102 for (i=0; i<RANDSIZ; i+=8)
104 /* fill in mm[] with messy stuff */
105 mix(a,b,c,d,e,f,g,h);
106 m[i ]=a; m[i+1]=b; m[i+2]=c; m[i+3]=d;
107 m[i+4]=e; m[i+5]=f; m[i+6]=g; m[i+7]=h;
111 isaac(ctx); /* fill in the first set of results */
112 ctx->randcnt=RANDSIZ; /* prepare to use the first set of results */
121 ctx.randa=ctx.randb=ctx.randc=(ub4)0;
122 for (i=0; i<256; ++i) ctx.randrsl[i]=(ub4)0;
123 randinit(&ctx, TRUE);
127 for (j=0; j<256; ++j)
129 printf("%.8lx",ctx.randrsl[j]);
130 if ((j&7)==7) printf("\n");