reactos/lib/sdk/crt/math/rand.c

   1 /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
   2 #include <precomp.h>
   3 #include <ntsecapi.h>
   4 #include <internal/tls.h>
   5
   6 /*
   7  * @implemented
   8  */
   9 int
  10 rand(void)
  11 {
  12     thread_data_t *data = msvcrt_get_thread_data();
  13
  14     /* this is the algorithm used by MSVC, according to
  15      * http://en.wikipedia.org/wiki/List_of_pseudorandom_number_generators */
  16     data->random_seed = data->random_seed * 214013 + 2531011;
  17     return (data->random_seed >> 16) & RAND_MAX;
  18 }
  19
  20 /*
  21  * @implemented
  22  */
  23 void
  24 srand(unsigned int seed)
  25 {
  26     thread_data_t *data = msvcrt_get_thread_data();
  27     data->random_seed = seed;
  28 }
  29
  30  /*********************************************************************
  31   *              rand_s (MSVCRT.@)
  32   */
  33 int CDECL rand_s(unsigned int *pval)
  34 {
  35     BOOLEAN (WINAPI *pSystemFunction036)(PVOID, ULONG); // RtlGenRandom
  36     HINSTANCE hadvapi32;
  37
  38     if (!pval)
  39     {
  40         _invalid_parameter(NULL,_CRT_WIDE("rand_s"),_CRT_WIDE(__FILE__),__LINE__, 0);
  41         *_errno() = EINVAL;
  42         return EINVAL;
  43     }
  44
  45     *pval = 0;
  46     hadvapi32 = LoadLibraryA("advapi32.dll");
  47     if (!hadvapi32)
  48     {
  49         _invalid_parameter(NULL,_CRT_WIDE("rand_s"),_CRT_WIDE(__FILE__),__LINE__, 0);
  50         *_errno() = EINVAL;
  51         return EINVAL;
  52     }
  53
  54     pSystemFunction036 = (void*)GetProcAddress(hadvapi32, "SystemFunction036");
  55     if (!pSystemFunction036)
  56     {
  57         _invalid_parameter(NULL,_CRT_WIDE("rand_s"),_CRT_WIDE(__FILE__),__LINE__, 0);
  58         *_errno() = EINVAL;
  59         FreeLibrary(hadvapi32);
  60         return EINVAL;
  61     }
  62
  63     if (!pSystemFunction036(pval, sizeof(*pval)))
  64     {
  65         _invalid_parameter(NULL,_CRT_WIDE("rand_s"),_CRT_WIDE(__FILE__),__LINE__, 0);
  66         *_errno() = EINVAL;
  67         FreeLibrary(hadvapi32);
  68         return EINVAL;
  69     }
  70
  71     FreeLibrary(hadvapi32);
  72     return 0;
  73 }