lib/libsys/get_randomness.c

   1 #include <lib.h>
   2
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <minix/profile.h>
   6 #include <minix/syslib.h>
   7 #include <minix/type.h>
   8 #include <minix/sysutil.h>
   9
  10 /*===========================================================================*
  11  *                              get_randomness                               *
  12  *===========================================================================*/
  13 PUBLIC void get_randomness(rand, source)
  14 struct k_randomness *rand;
  15 int source;
  16 {
  17 /* Use architecture-dependent high-resolution clock for
  18  * raw entropy gathering.
  19  */
  20   int r_next;
  21   unsigned long tsc_high, tsc_low;
  22
  23   source %= RANDOM_SOURCES;
  24   r_next= rand->bin[source].r_next;
  25   read_tsc(&tsc_high, &tsc_low);
  26   rand->bin[source].r_buf[r_next] = tsc_low;
  27   if (rand->bin[source].r_size < RANDOM_ELEMENTS) {
  28         rand->bin[source].r_size ++;
  29   }
  30   rand->bin[source].r_next = (r_next + 1 ) % RANDOM_ELEMENTS;
  31 }
  32
  33