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Member "udns-0.4/udns_jran.c" (5 Jul 2011, 1513 Bytes) of package /linux/misc/dns/udns-0.4.tar.gz:

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    1 /* udns_jran.c: small non-cryptographic random number generator
    2  * taken from http://burtleburtle.net/bob/rand/smallprng.html
    3  * by Bob Jenkins, Public domain.
    4  */
    5 
    6 #include "udns.h"
    7 
    8 #define rot32(x,k) (((x) << (k)) | ((x) >> (32-(k))))
    9 #define rot64(x,k) (((x) << (k)) | ((x) >> (64-(k))))
   10 #define tr32(x) ((x)&0xffffffffu)
   11 
   12 unsigned udns_jranval(struct udns_jranctx *x) {
   13   /* This routine can be made to work with either 32 or 64bit words -
   14    * if JRAN_32_64 is defined when compiling the file.
   15    * We use if() instead of #if since there's no good
   16    * portable way to check sizeof() in preprocessor without
   17    * introducing some ugly configure-time checks.
   18    * Most compilers will optimize the wrong branches away anyway.
   19    * By default it assumes 32bit integers
   20    */
   21 #ifdef JRAN_32_64
   22   if (sizeof(unsigned) == 4) {
   23 #endif
   24     unsigned e = tr32(x->a - rot32(x->b, 27));
   25     x->a = tr32(x->b ^ rot32(x->c, 17));
   26     x->b = tr32(x->c + x->d);
   27     x->c = tr32(x->d + e);
   28     x->d = tr32(e + x->a);
   29 #ifdef JRAN_32_64
   30   }
   31   else if (sizeof(unsigned) == 8) { /* assuming it's 64bits */
   32     unsigned e = x->a - rot64(x->b, 7);
   33     x->a = x->b ^ rot64(x->c, 13);
   34     x->b = x->c + rot64(x->d, 37);
   35     x->c = x->d + e;
   36     x->d = e + x->a;
   37   }
   38   else {
   39     unsigned e = 0;
   40     x->d = 1/e; /* bail */
   41   }
   42 #endif
   43   return x->d;
   44 }
   45 
   46 void udns_jraninit(struct udns_jranctx *x, unsigned seed) {
   47   unsigned i;
   48   x->a = 0xf1ea5eed;
   49   x->b = x->c = x->d = seed;
   50   for (i = 0; i < 20; ++i)
   51      (void)udns_jranval(x);
   52 }