kc3-lang/libtommath/demo/s_mp_rand_jenkins.c

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• Hash : 34e16d3c
  Author :
  Date : 2020-09-13T19:06:43
  

  allow testing of shared library * move jenkins' prng out of the library into the demo's. * add CI test for shared library

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• demo/s_mp_rand_jenkins.c

• #include "tommath_private.h"
  #ifdef S_MP_RAND_JENKINS_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* Bob Jenkins' http://burtleburtle.net/bob/rand/smallprng.html */
  /* Chosen for speed and a good "mix" */
  
  /* TODO: jenkins prng is not thread safe as of now */
  
  typedef struct {
     uint64_t a;
     uint64_t b;
     uint64_t c;
     uint64_t d;
  } ranctx;
  
  static ranctx jenkins_x;
  
  #define rot(x,k) (((x)<<(k))|((x)>>(64-(k))))
  static uint64_t s_rand_jenkins_val(void)
  {
     uint64_t e = jenkins_x.a - rot(jenkins_x.b, 7);
     jenkins_x.a = jenkins_x.b ^ rot(jenkins_x.c, 13);
     jenkins_x.b = jenkins_x.c + rot(jenkins_x.d, 37);
     jenkins_x.c = jenkins_x.d + e;
     jenkins_x.d = e + jenkins_x.a;
     return jenkins_x.d;
  }
  
  static void s_mp_rand_jenkins_init(uint64_t seed)
  {
     int i;
     jenkins_x.a = 0xF1EA5EEDuL;
     jenkins_x.b = jenkins_x.c = jenkins_x.d = seed;
     for (i = 0; i < 20; ++i) {
        (void)s_rand_jenkins_val();
     }
  }
  
  static mp_err s_mp_rand_jenkins(void *p, size_t n)
  {
     char *q = (char *)p;
     while (n > 0u) {
        int i;
        uint64_t x = s_rand_jenkins_val();
        for (i = 0; (i < 8) && (n > 0u); ++i, --n) {
           *q++ = (char)(x & 0xFFu);
           x >>= 8;
        }
     }
     return MP_OKAY;
  }
  
  #endif
  

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