Add time support (time, gettimeofday, etc.) (#138)

cores/rp2040/main.cpp

@@ -149,12 +149,27 @@ extern "C" int _getpid (void) {
     return -1;
 }
 
-struct timeval;
 
-extern "C" int _gettimeofday (struct timeval  *ptimeval, void *ptimezone)
-{
-    errno = ENOSYS;
-    return -1;
+static int64_t __timedelta_us = 0.0;
+
+extern "C" int _gettimeofday (struct timeval *tv, void *tz) {
+    uint64_t now_us = to_us_since_boot(get_absolute_time()) + __timedelta_us;
+    if (tv) {
+        tv->tv_sec = now_us / 1000000L;
+        tv->tv_usec = now_us % 1000000L;
+    }
+    return 0;
+}
+
+extern "C" int settimeofday (const struct timeval *tv, const struct timezone *tz) {
+    uint64_t now_us = to_us_since_boot(get_absolute_time());
+    if (tv) {
+        uint64_t newnow_us;
+        newnow_us = tv->tv_sec * 1000000L;
+        newnow_us += tv->tv_usec;
+        __timedelta_us = newnow_us - now_us;
+    }
+    return 0;
 }
 
 extern "C" int _isatty (int file) {

libraries/rp2040/examples/Time/Time.ino

@@ -0,0 +1,28 @@
+/* Simple demonstration of setting and printing the current time */
+/* The initial time will need to come from an RTC, NTP, or user */
+
+/* Released to the public domain by Earle F. Philhower, III <earlephilhower@yahoo.com> */
+
+#include <time.h>
+#include <sys/time.h>
+
+void setup() {
+  Serial.begin(115200);
+  delay(5000);
+  struct timeval tv;
+
+  tv.tv_sec = 1611198855; // Jan 21, 2021  3:14:15AM ...RPi Pico Release;
+  tv.tv_usec = 0;
+  settimeofday(&tv, nullptr);
+}
+
+void loop() {
+  time_t now;
+  struct tm *info;
+  char buff[80];
+
+  time(&now);
+  strftime(buff, sizeof(buff), "%c", localtime(&now));
+  Serial.println(buff);
+  delay(1000);
+}