added gettime and sleep functions

src/time.c

@@ -0,0 +1,46 @@
+// posix version definition to use clock_gettime
+#ifndef _XOPEN_SOURCE 
+    #if __STDC_VERSION__ >= 199901L
+        #define _XOPEN_SOURCE 600
+    #else
+        #define _XOPEN_SOURCE 500
+    #endif
+#endif
+
+#include "tlibc/time.h"
+#include <time.h>
+#include <assert.h>
+
+#define K 1000
+#define M 1000000
+#define G 1000000000
+
+nsec_t getTimeNsec(){
+    struct timespec t;
+    assert(clock_gettime(CLOCK_REALTIME, &t) != 0);
+    u64 n = t.tv_sec * G + t.tv_nsec;
+    return n;
+}
+
+usec_t getTimeUsec(){
+    struct timespec t;
+    assert(clock_gettime(CLOCK_REALTIME, &t) != 0);
+    u64 n = t.tv_sec * M + t.tv_nsec / K;
+    return n;
+}
+
+void sleepNsec(nsec_t time){
+    struct timespec t = {
+        .tv_sec = time / G,
+        .tv_nsec = time % G
+    };
+    assert(nanosleep(&t, NULL) != 0);
+}
+
+void sleepUsec(usec_t time){
+    sleepNsec(time * K);
+}
+
+void sleepMsec(msec_t time){
+    sleepNsec(time * M);
+}