feat(newlib): Add time support

components/newlib/component.mk

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+#
+# Component Makefile
+#
+COMPONENT_SRCDIRS := .

components/newlib/time.c

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+// Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdint.h>
+#include <reent.h>
+#include <sys/time.h>
+
+#include "esp_system.h"
+#include "esp_timer.h"
+
+static uint64_t s_boot_time;
+
+static os_timer_t microsecond_overflow_timer;
+static uint32_t microsecond_last_overflow_tick;
+static uint32_t microsecond_overflow_count;
+
+static bool microsecond_overflow_timer_start_flag = false;
+
+static void microsecond_overflow_tick(void* arg)
+{
+    uint32_t m = system_get_time();
+
+    if (m < microsecond_last_overflow_tick) {
+        microsecond_overflow_count ++;
+    }
+
+    microsecond_last_overflow_tick = m;
+}
+
+/* Start a timer which period is 60s to check the overflow of microsecond. */
+static void microsecond_overflow_set_check_timer(void)
+{
+    if (microsecond_overflow_timer_start_flag == false) {
+        os_timer_disarm(&microsecond_overflow_timer);
+        os_timer_setfn(&microsecond_overflow_timer, (os_timer_func_t*)microsecond_overflow_tick, 0);
+        os_timer_arm(&microsecond_overflow_timer, 60 * 1000, 1);
+
+        microsecond_overflow_timer_start_flag = true;
+    }
+}
+
+static void set_boot_time(uint64_t time_us)
+{
+    s_boot_time = time_us;
+}
+
+static uint64_t get_boot_time()
+{
+    uint64_t result;
+
+    result = s_boot_time;
+
+    return result;
+}
+
+static uint64_t get_time_since_boot()
+{
+    uint32_t m = system_get_time();
+    uint32_t c = microsecond_overflow_count + ((m < microsecond_last_overflow_tick) ? 1 : 0);
+
+    uint64_t microseconds = c * (1LL << 32) + m;
+
+    return microseconds;
+}
+
+int _gettimeofday_r(struct _reent* r, struct timeval* tv, void* tz)
+{
+    (void) tz;
+
+    /* ToDo: This can be moved to system start up. */
+    microsecond_overflow_set_check_timer();
+
+    if (tv) {
+        uint64_t microseconds = get_boot_time() + get_time_since_boot();
+        tv->tv_sec = microseconds / 1000000;
+        tv->tv_usec = microseconds % 1000000;
+    }
+
+    return 0;
+}
+
+int settimeofday(const struct timeval* tv, const struct timezone* tz)
+{
+    (void) tz;
+
+    microsecond_overflow_set_check_timer();
+
+    if (tv) {
+        uint64_t now = ((uint64_t) tv->tv_sec) * 1000000LL + tv->tv_usec;
+        uint64_t since_boot = get_time_since_boot();
+        set_boot_time(now - since_boot);
+    }
+
+    return 0;
+}