Support for gettime and sleep functions

Provide `gettime` and `sleep` functions with at least 1 millisecond
resolution.

1 files changed, 89 insertions, 0 deletions

diff --git a/src/time.c b/src/time.c
new file mode 100644
index 0000000..3f61001
--- /dev/null
+++ b/src/time.c
@@ -0,0 +1,89 @@
+#include <lua.h>
+#include <lauxlib.h>
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <time.h>
+#include <sys/time.h>
+#endif
+
+#include "compat.h"
+
+/*-------------------------------------------------------------------------
+ * Gets time in s, relative to January 1, 1970 (UTC)
+ * Returns
+ *   time in s.
+ *-------------------------------------------------------------------------*/
+#ifdef _WIN32
+static double time_gettime(void) {
+    FILETIME ft;
+    double t;
+    GetSystemTimeAsFileTime(&ft);
+    /* Windows file time (time since January 1, 1601 (UTC)) */
+    t  = ft.dwLowDateTime/1.0e7 + ft.dwHighDateTime*(4294967296.0/1.0e7);
+    /* convert to Unix Epoch time (time since January 1, 1970 (UTC)) */
+    return (t - 11644473600.0);
+}
+#else
+static double time_gettime(void) {
+    struct timeval v;
+    gettimeofday(&v, (struct timezone *) NULL);
+    /* Unix Epoch time (time since January 1, 1970 (UTC)) */
+    return v.tv_sec + v.tv_usec/1.0e6;
+}
+#endif
+
+/*-------------------------------------------------------------------------
+ * Returns the time the system has been up, in secconds.
+ *-------------------------------------------------------------------------*/
+static int time_lua_gettime(lua_State *L)
+{
+    lua_pushnumber(L, time_gettime());
+    return 1;
+}
+
+/*-------------------------------------------------------------------------
+ * Sleep for n seconds.
+ *-------------------------------------------------------------------------*/
+#ifdef _WIN32
+static int time_lua_sleep(lua_State *L)
+{
+    double n = luaL_checknumber(L, 1);
+    if (n < 0.0) n = 0.0;
+    if (n < DBL_MAX/1000.0) n *= 1000.0;
+    if (n > INT_MAX) n = INT_MAX;
+    Sleep((int)n);
+    return 0;
+}
+#else
+static int time_lua_sleep(lua_State *L)
+{
+    double n = luaL_checknumber(L, 1);
+    struct timespec t, r;
+    if (n < 0.0) n = 0.0;
+    if (n > INT_MAX) n = INT_MAX;
+    t.tv_sec = (int) n;
+    n -= t.tv_sec;
+    t.tv_nsec = (int) (n * 1000000000);
+    if (t.tv_nsec >= 1000000000) t.tv_nsec = 999999999;
+    while (nanosleep(&t, &r) != 0) {
+        t.tv_sec = r.tv_sec;
+        t.tv_nsec = r.tv_nsec;
+    }
+    return 0;
+}
+#endif
+
+static luaL_Reg func[] = {
+    { "gettime", time_lua_gettime },
+    { "sleep", time_lua_sleep },
+    { NULL, NULL }
+};
+
+/*-------------------------------------------------------------------------
+ * Initializes module
+ *-------------------------------------------------------------------------*/
+void time_open(lua_State *L) {
+    luaL_setfuncs(L, func, 0);
+}