AP_Scripting: fixed use of clock and time in lua

not available on stm32

libraries/AP_Scripting/lua/src/lauxlib.c

@@ -1044,3 +1044,15 @@ LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver, size_t sz) {
                   (LUAI_UACNUMBER)ver, (LUAI_UACNUMBER)*v);
 }
 
+
+/*
+  32 bit random number generator for lua internals
+ */
+uint32_t lua_random32(void)
+{
+    static uint32_t m_z = 1234;
+    static uint32_t m_w = 76542;
+    m_z = 36969 * (m_z & 0xFFFFu) + (m_z >> 16);
+    m_w = 18000 * (m_w & 0xFFFFu) + (m_w >> 16);
+    return ((m_z << 16) + m_w);
+}

libraries/AP_Scripting/lua/src/lauxlib.h

@@ -36,6 +36,8 @@ typedef struct luaL_Reg {
 
 #define LUAL_NUMSIZES	(sizeof(lua_Integer)*16 + sizeof(lua_Number))
 
+uint32_t lua_random32(void);
+
 LUALIB_API void (luaL_checkversion_) (lua_State *L, lua_Number ver, size_t sz);
 #define luaL_checkversion(L)  \
 	  luaL_checkversion_(L, LUA_VERSION_NUM, LUAL_NUMSIZES)

libraries/AP_Scripting/lua/src/lstate.c

@@ -26,6 +26,7 @@
 #include "lstring.h"
 #include "ltable.h"
 #include "ltm.h"
+#include "lauxlib.h"
 
 // lua code does lots of casting, these warnings are not helpful
 #pragma GCC diagnostic ignored "-Wcast-align"
@@ -44,10 +45,14 @@
 ** a macro to help the creation of a unique random seed when a state is
 ** created; the seed is used to randomize hashes.
 */
+#if defined(ARDUPILOT_BUILD)
+#define luai_makeseed() lua_random32()
+#else
 #if !defined(luai_makeseed)
 #include <time.h>
 #define luai_makeseed()		cast(unsigned int, time(NULL))
 #endif
+#endif
 
 
 

libraries/AP_Scripting/lua/src/ltablib.c

@@ -256,6 +256,9 @@ typedef unsigned int IdxT;
 ** is to copy them to an array of a known type and use the array values.
 */
 static unsigned int l_randomizePivot (void) {
+#if defined(ARDUPILOT_BUILD)
+  return lua_random32();
+#else
   clock_t c = clock();
   time_t t = time(NULL);
   unsigned int buff[sof(c) + sof(t)];
@@ -265,6 +268,7 @@ static unsigned int l_randomizePivot (void) {
   for (i = 0; i < sof(buff); i++)
     rnd += buff[i];
   return rnd;
+#endif
 }
 
 #endif					/* } */