Merge pull request #4653 from mysterywolf/fixed-timezone

[libc][time]增加手动设置固定时区的功能

components/libc/Kconfig

@@ -55,8 +55,14 @@ endif
 
 if RT_USING_LIBC != y
     config RT_LIBC_USING_TIME
-    bool "Enable TIME FUNCTIONS WITHOUT COMPILER'S LIBC"
+    bool "Enable time functions without compiler's libc"
     default y
 endif
 
+config RT_LIBC_FIXED_TIMEZONE
+    depends on (RT_LIBC_USING_TIME || RT_USING_LIBC)
+    int "Manually set a fixed time zone (UTC+)"
+    range -12 12
+    default 8
+
 endmenu

components/libc/compilers/common/time.c

@@ -30,6 +30,10 @@
 #define DBG_LVL    DBG_INFO
 #include <rtdbg.h>
 
+#ifndef RT_LIBC_FIXED_TIMEZONE
+#define RT_LIBC_FIXED_TIMEZONE 8 /* UTC+8 */
+#endif
+
 /* seconds per day */
 #define SPD 24*60*60
 
@@ -208,14 +212,11 @@ struct tm* gmtime(const time_t* t)
 }
 RTM_EXPORT(gmtime);
 
-/*TODO: timezone */
 struct tm* localtime_r(const time_t* t, struct tm* r)
 {
     time_t local_tz;
-    int utc_plus;
 
-    utc_plus = 8; /* GMT: UTC+8 */
-    local_tz = *t + utc_plus * 3600;
+    local_tz = *t + RT_LIBC_FIXED_TIMEZONE * 3600;
     return gmtime_r(&local_tz, r);
 }
 RTM_EXPORT(localtime_r);
@@ -227,15 +228,12 @@ struct tm* localtime(const time_t* t)
 }
 RTM_EXPORT(localtime);
 
-/* TODO: timezone */
 time_t mktime(struct tm * const t)
 {
     time_t timestamp;
-    int utc_plus;
 
-    utc_plus = 8; /* GMT: UTC+8 */
     timestamp = timegm(t);
-    timestamp = timestamp - 3600 * utc_plus;
+    timestamp = timestamp - 3600 * RT_LIBC_FIXED_TIMEZONE;
     return timestamp;
 }
 RTM_EXPORT(mktime);