ESP8266_RTOS example tweaks

PUBLISHED_FROM=11096f272afc0716e0677c68d58ebf4d4e001a47

examples/ESP8266_RTOS/user/esp_libc.c

@@ -16,7 +16,6 @@
 #include "esp_common.h"
 
 /* Makes fprintf(stdout) and stderr work. */
-/*
 _ssize_t _write_r(struct _reent *r, int fd, void *buf, size_t len) {
   if (fd == 1 || fd == 2) {
     size_t i;
@@ -27,7 +26,6 @@ _ssize_t _write_r(struct _reent *r, int fd, void *buf, size_t len) {
   }
   return -1;
 }
-*/
 
 /*
  * You'll need to implement _open_r and friends if you want file operations. See
@@ -47,9 +45,21 @@ void _exit(int status) {
   abort();
 }
 
+/*
+ * This will prevent counter wrap if time is read regularly.
+ * At least Mongoose poll queries time, so we're covered.
+ */
 int _gettimeofday_r(struct _reent *r, struct timeval *tp, void *tzp) {
+  static uint32_t prev_time = 0;
+  static uint32_t num_overflows = 0;
   uint32_t time = system_get_time();
-  tp->tv_sec = time / 1000000;
-  tp->tv_usec = time % 1000000;
+  uint64_t time64 = time;
+  if (prev_time > 0 && time < prev_time) num_overflows++;
+  time64 += (((uint64_t) num_overflows) * (1ULL << 32));
+  tp->tv_sec = time64 / 1000000ULL;
+  tp->tv_usec = time64 % 1000000ULL;
+  prev_time = time;
   return 0;
+  (void) r;
+  (void) tzp;
 }