Generate seed numbers from a microseconds clock, not a seconds clock

src/frontend/inp.c

@@ -89,6 +89,16 @@ extern void exec_controls(wordlist *controls);
 extern void SetSource(char *Name);
 #endif
 
+#if defined (_MSC_VER) || defined (__MINGW32__)
+typedef struct timeval {
+    long tv_sec;
+    long tv_usec;
+} timeval;
+
+extern int gettimeofday(struct timeval* tp, void* unused);
+#endif
+
+
 /* structure used to save expression parse trees for .model and
  * device instance lines
  */
@@ -101,6 +111,7 @@ struct pt_temper {
     struct pt_temper *next;
 };
 
+
 static int inp_parse_temper(struct card *deck,
                             struct pt_temper **motdlist_p,
                             struct pt_temper **devtlist_p);
@@ -439,9 +450,10 @@ eval_opt(struct card* deck)
             char* token = gettok(&begtok);
             /* option seed=random [seed='random'] */
             if (eq(token, "random") || eq(token, "{random}")) {
-                time_t acttime = time(NULL);
-                /* get random value from time in seconds since 1.1.1970 */
-                int rseed = (int)(acttime - 1600000000);
+                struct timeval tv;
+                gettimeofday(&tv, NULL);
+                /* get random value from current timestamp microseconds */
+                int rseed = (int)(tv.tv_usec);
                 cp_vset("rndseed", CP_NUM, &rseed);
                 com_sseed(NULL);
                 has_seed = TRUE;

src/misc/win_time.c

@@ -0,0 +1,32 @@
+#define WIN32_LEAN_AND_MEAN
+//#include "ngspice/ngspice.h"
+#include <Windows.h>
+#include <winsock2.h>
+#include <stdint.h> // portable: uint64_t   MSVC: __int64 
+
+/*/ MSVC defines this in winsock2.h!?
+typedef struct timeval {
+    long tv_sec;
+    long tv_usec;
+} timeval;
+*/
+int gettimeofday(struct timeval * tp, void * unused)
+{
+    // Note: some broken versions only have 8 trailing zero's, the correct epoch has 9 trailing zero's
+    // This magic number is the number of 100 nanosecond intervals since January 1, 1601 (UTC)
+    // until 00:00:00 January 1, 1970 
+    static const uint64_t EPOCH = ((uint64_t) 116444736000000000ULL);
+
+    SYSTEMTIME  system_time;
+    FILETIME    file_time;
+    uint64_t    time;
+
+    GetSystemTime( &system_time );
+    SystemTimeToFileTime( &system_time, &file_time );
+    time =  ((uint64_t)file_time.dwLowDateTime )      ;
+    time += ((uint64_t)file_time.dwHighDateTime) << 32;
+
+    tp->tv_sec  = (long) ((time - EPOCH) / 10000000L);
+    tp->tv_usec = (long) (system_time.wMilliseconds * 1000);
+    return 0;
+}

visualc/sharedspice.vcxproj

@@ -1220,6 +1220,7 @@
     <ClCompile Include="..\src\misc\string.c" />
     <ClCompile Include="..\src\misc\tilde.c" />
     <ClCompile Include="..\src\misc\util.c" />
+    <ClCompile Include="..\src\misc\win_time.c" />
     <ClCompile Include="..\src\misc\wlist.c" />
     <ClCompile Include="..\src\ngspice.c" />
     <ClCompile Include="..\src\osdi\osdiacld.c" />

visualc/vngspice-fftw.vcxproj

@@ -1685,6 +1685,7 @@ lib /machine:x64 /def:..\..\fftw-3.3-dll64\libfftw3-3.def /out:$(IntDir)libfftw3
     <ClCompile Include="..\src\misc\string.c" />
     <ClCompile Include="..\src\misc\tilde.c" />
     <ClCompile Include="..\src\misc\util.c" />
+    <ClCompile Include="..\src\misc\win_time.c" />
     <ClCompile Include="..\src\misc\wlist.c" />
     <ClCompile Include="..\src\ngspice.c" />
     <ClCompile Include="..\src\osdi\osdiacld.c" />

visualc/vngspice.vcxproj

@@ -1700,6 +1700,7 @@
     <ClCompile Include="..\src\misc\string.c" />
     <ClCompile Include="..\src\misc\tilde.c" />
     <ClCompile Include="..\src\misc\util.c" />
+    <ClCompile Include="..\src\misc\win_time.c" />
     <ClCompile Include="..\src\misc\wlist.c" />
     <ClCompile Include="..\src\ngspice.c" />
     <ClCompile Include="..\src\osdi\osdiacld.c" />