add difftime()

components/libc/compilers/common/time.c

@@ -12,6 +12,7 @@
  * 2021-02-08     Meco Man     add settimeofday() stime()
  * 2021-02-10     Meco Man     add ctime_r() and re-implement ctime()
  * 2021-02-11     Meco Man     fix bug #3183 - align days[] and months[] to 4 bytes
+ *                             add difftime()
  */
 
 #include <sys/time.h>
@@ -163,6 +164,11 @@ char* ctime(const time_t *tim_p)
     return asctime (localtime (tim_p));
 }
 
+double difftime (time_t tim1, time_t tim2)
+{
+    return (double)(tim1 - tim2);
+}
+
 /**
  * Returns the current time.
  *