time: add support for C99 <time.h> (DONE)

CMakeLists.txt

@@ -192,7 +192,15 @@ set(SOURCES
   src/libc/string/strstr.c
   src/libc/string/strstr_base.c
   src/libc/string/strtok.c
-  src/libc/string/strxfrm.c)
+  src/libc/string/strxfrm.c
+  # time
+  src/libc/time/asctime.c
+  src/libc/time/ctime.c
+  src/libc/time/difftime.c
+  src/libc/time/gmtime.c
+  src/libc/time/localtime.c
+  src/libc/time/mktime.c
+  src/libc/time/strftime.c)
 
 # Silence extended warnings on Grisu2b code
 set_source_files_properties(3rdparty/grisu2b_59_56/grisu2b_59_56.c PROPERTIES
@@ -239,9 +247,13 @@ endif()
 
 if(gint IN_LIST TARGET_FOLDERS)
   list(APPEND SOURCES
+    # stdlib
     src/libc/stdlib/target/gint/free.c
     src/libc/stdlib/target/gint/malloc.c
-    src/libc/stdlib/target/gint/realloc.c)
+    src/libc/stdlib/target/gint/realloc.c
+    # time
+    src/libc/time/target/gint/clock.c
+    src/libc/time/target/gint/time.c)
 endif()
 
 if(casiowin-fx IN_LIST TARGET_FOLDERS)

STATUS

@@ -157,16 +157,16 @@ DONE:       Function/symbol/macro is defined, builds, links, and is tested
 7.22 <tgmath.h> => GCC
 
 7.23 <time.h>
-!    7.23.1    Components of time: TODO
-!    7.23.2.1  clock: TODO
-!    7.23.2.2  difftime: TODO
-!    7.23.2.3  mktime: TODO
-!    7.23.2.4  time: TODO
-!    7.23.3.1  asctime: TODO
-!    7.23.3.2  ctime: TODO
-!    7.23.3.3  gmtime: TODO
-!    7.23.3.4  localtime: TODO
-!    7.23.3.5  strftime: TODO
+     7.23.1    Components of time: DONE
+     7.23.2.1  clock: DONE
+     7.23.2.2  difftime: DONE
+     7.23.2.3  mktime: DONE     (DST flag ignored)
+     7.23.2.4  time: DONE
+     7.23.3.1  asctime: DONE
+     7.23.3.2  ctime: DONE
+     7.23.3.3  gmtime: DONE
+     7.23.3.4  localtime: DONE  (No timezones; same as gmtime)
+     7.23.3.5  strftime: DONE   (No %g/%G/%U/%V/%W; timezones %z/%Z empty)
 
 7.24 <wchar.h>
      TODO (not a priority)
@@ -184,6 +184,7 @@ What if we wanted to support more locales?
 -> Fix the "TODO: locale: ..." messages wherever assumptions on the locale are
    made in the code
 -> Properly implement strcoll() and strxfrm()
+-> Add support in strftime()
 
 # Supporting text and binary files (newline translation)
 
@@ -195,3 +196,8 @@ This requires all the wide-char functions but also updating fpos_t to be a
 structure with at least some mbstate_t member (7.19.2§6).
 
 I really don't want to do that. Use multi-byte functions with UTF-8.
+
+# Supporting timezones
+
+-> Update localtime()
+-> Add some timezone API

include/time.h

@@ -5,28 +5,65 @@
 extern "C" {
 #endif
 
-/* Number of ticks per second in a clock_t value. */
+#include <stddef.h>
+#include <stdint.h>
+
+/* Number of ticks per second in a clock_t value. This is not necessarily the
+   full precision (eg. the RTC has only 128 units per second). */
 #define CLOCKS_PER_SEC 1000000
 
-/* Type used to represent process CPU time; unit is CLOCKS_PER_SEC. */
+/* Represent process CPU time; unit is CLOCKS_PER_SEC. */
 typedef uint64_t clock_t;
 
-/* Type used to represent a number of seconds since Epoch. */
-typedef uint64_t time_t;
+/* Represent a number of seconds since 1970-01-01 00:00:00 +0000 (UTC). */
+typedef int64_t time_t;
 
 /* Broken-down time. */
 struct tm {
-	int tm_sec;
-	int tm_min;
-	int tm_hour;
-	int tm_mday;
-	int tm_mon;
-	int tm_year;
-	int tm_wday;
-	int tm_yday;
-	int tm_isdst;
+	int tm_sec;     /* Seconds (0..60) */
+	int tm_min;     /* Minutes (0..59) */
+	int tm_hour;    /* Hours (0..23) */
+	int tm_mday;    /* Day of month (1..31) */
+	int tm_mon;     /* Month (0..11) */
+	int tm_year;    /* Years since 1900 */
+	int tm_wday;    /* Day of week, starting Sunday (0..6) */
+	int tm_yday;    /* Day of year (0..365) */
+	int tm_isdst;   /* Daylight Saving Time flag */
 };
 
+/* Returns CPU time used by the program (in number of CLOCKS_PER_SEC). */
+extern clock_t clock(void);
+
+/* Time elapsed between __start and __end, in seconds. */
+double difftime(time_t __end, time_t __start);
+
+/* Normalizes __time and returns associated timestamp.
+   TODO: Currently ignores the [tm_isdst] field. */
+extern time_t mktime(struct tm *__time);
+
+/* Determine current timestamp; also set it in __timeptr if non-NULL. */
+extern time_t time(time_t *__timeptr);
+
+/* Text representation, like "Sun Sep 16 01:03:52 1973\n". The returned string
+   is statically allocated and is overwritten by every call. */
+extern char *asctime(const struct tm *__time);
+
+/* Convert calendar time to asctime()'s text representation. */
+extern char *ctime(const time_t *__time);
+
+/* Convert calendar time to broken-down time as UTC. */
+extern struct tm *gmtime(const time_t *__time);
+
+/* Convert calendar time to broken-down local time.
+   TODO: We don't have timezones so this always returns UTC. */
+extern struct tm *localtime(const time_t *time);
+
+/* Formats __time according to the specified format; similar to snprintf().
+   TODO: %g, %G, %V (week-based year), and %U, %W (week number) are not
+         supported and substituted by "??". %z and %Z output nothing. */
+size_t strftime(char * restrict __s, size_t __maxsize,
+	const char * restrict __format, const struct tm * restrict __time);
+
 #ifdef __cplusplus
 }
 #endif

src/libc/time/asctime.c

@@ -0,0 +1,21 @@
+#include <time.h>
+#include <stdio.h>
+
+static const char wday_name[8][3] = {
+	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "???"
+};
+static const char mon_name[13][3] = {
+	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "???"
+};
+
+char *asctime(const struct tm *time)
+{
+	int wday = ((unsigned int)time->tm_wday < 7) ? time->tm_wday : 7;
+	int mon  = ((unsigned int)time->tm_mon < 12) ? time->tm_mon : 12;
+	static char str[26];
+	sprintf(str, "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n",
+		wday_name[wday], mon_name[mon], time->tm_mday, time->tm_hour,
+		time->tm_min, time->tm_sec, time->tm_year + 1900);
+	return str;
+}

src/libc/time/ctime.c

@@ -0,0 +1,6 @@
+#include <time.h>
+
+char *ctime(const time_t *time)
+{
+	return asctime(localtime(time));
+}

src/libc/time/difftime.c

@@ -0,0 +1,6 @@
+#include <time.h>
+
+double difftime(time_t t1, time_t t0)
+{
+	return (double)(t1 - t0);
+}

src/libc/time/gmtime.c

@@ -0,0 +1,20 @@
+#include <time.h>
+#include "timeutil.h"
+
+struct tm *gmtime(const time_t *timeptr)
+{
+	static struct tm t;
+
+	/* Specify Epoch + *timeptr seconds */
+	t.tm_year  = 1970 - 1900;
+	t.tm_mon   = 0;
+	t.tm_mday  = 1;
+	t.tm_hour  = 0;
+	t.tm_min   = 0;
+	t.tm_sec   = *timeptr;
+	t.tm_isdst = 0;
+
+	/* Then let mktime() do all the hard work */
+	mktime(&t);
+	return &t;
+}

src/libc/time/localtime.c

@@ -0,0 +1,7 @@
+#include <time.h>
+
+/* TODO: localtime: No timezone specification is supported */
+struct tm *localtime(const time_t *time)
+{
+	return gmtime(time);
+}

src/libc/time/mktime.c

@@ -0,0 +1,58 @@
+#include <time.h>
+#include "timeutil.h"
+
+/* TODO: mktime: DST not supported */
+time_t mktime(struct tm *time)
+{
+	/* Normalize time */
+	time->tm_min   += (time->tm_sec / 60);
+	time->tm_hour  += (time->tm_min / 60);
+	time->tm_mday  += (time->tm_hour / 24);
+	time->tm_sec   %= 60;
+	time->tm_min   %= 60;
+	time->tm_hour  %= 24;
+
+	/* Normalize date */
+	int days = daysin(time->tm_mon, time->tm_year + 1900);
+	while(time->tm_mday > days) {
+		time->tm_mday -= days;
+		if(++time->tm_mon == 12) {
+			time->tm_mon = 0;
+			time->tm_year++;
+		}
+		days = daysin(time->tm_mon, time->tm_year + 1900);
+	}
+
+	/* Determine day in year */
+	time->tm_yday = time->tm_mday - 1;
+	for(int i = 0; i < time->tm_mon; i++)
+		time->tm_yday += daysin(i, time->tm_year + 1900);
+
+	/* Determine day in week. The calendar has a period of 400 years and
+	   1601-01-01 was a Monday. */
+
+	/* Years elapsed since last 400n+1 year (1601-2001-etc). */
+	int yr = (time->tm_year + 1900 - 1) % 400;
+	/* Leap years during this period */
+	int leaps = (yr / 4) - (yr >= 100) - (yr >= 200) - (yr >= 300);
+	/* Days elapsed since 01-01 on the last 400n+1 year */
+	days = 365 * yr + leaps + time->tm_yday;
+	/* Current day of week (1 is Monday on 01-01 of last 400n+1 year) */
+	time->tm_wday = (1 + days) % 7;
+
+	/* We don't determine DST at the targeted time */
+	time->tm_isdst = 0;
+
+	/* Number of periods elapsed since 1601-01-01 (may be negative) */
+	int periods = (time->tm_year + 1900 - 1601) / 400;
+	periods -= (time->tm_year + 1900 < 1601);
+	/* Days elapsed since 1970-01-01; the calendar period is 146097 days
+	   and there are 134774 days between 1601-01-01 and 1970-01-01 */
+	days += 146097 * periods - 134774;
+
+	time_t t = days;
+	t = 24 * t + time->tm_hour;
+	t = 60 * t + time->tm_min;
+	t = 60 * t + time->tm_sec;
+	return t;
+}

src/libc/time/strftime.c

@@ -0,0 +1,94 @@
+#include <time.h>
+#include <stdio.h>
+
+static const char *day_names[7] = {
+	"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
+	"Saturday",
+};
+static const char *month_names[12] = {
+	"January", "February", "March", "April", "May", "June", "July",
+	"August", "September", "October", "November", "December",
+};
+
+/* Perform a call to snprintf() to print a value */
+#define do_snprintf(...) { \
+	size_t _written = snprintf(s+len, n-len, __VA_ARGS__); \
+	len += _written; \
+	if(len >= n) goto full; \
+}; break
+/* Perform a sub-call to strftime to expand a complex format */
+#define do_strftime(fmt) { \
+	size_t _written = strftime2(s+len, n-len, fmt, time); \
+	if(_written == 0) goto full; \
+	len += _written; \
+}; break
+
+size_t strftime2(char * restrict s, size_t n, const char * restrict format,
+	const struct tm * restrict time)
+{
+	size_t len = 0;
+
+	while(*format) {
+		if(*format != '%') {
+			s[len++] = *format++;
+			if(len >= n) goto full;
+			continue;
+		}
+		format++;
+		int c = *format++;
+
+		/* In the "C" locale, ignore modifiers E and O */
+		if(c == 'E') c = *format++;
+		else if(c == 'O') c = *format++;
+
+		switch(c) {
+		case 'a': do_snprintf("%.3s", day_names[time->tm_wday]);
+		case 'A': do_snprintf("%s",   day_names[time->tm_wday]);
+		case 'b': do_snprintf("%.3s", month_names[time->tm_mon]);
+		case 'B': do_snprintf("%s",   month_names[time->tm_mon]);
+		case 'c': do_strftime("%a %b %e %T %Y");
+		case 'C': do_snprintf("%02d", (time->tm_year + 1900) / 100);
+		case 'd': do_snprintf("%02d", time->tm_mday);
+		case 'D': do_strftime("%m/%d/%y");
+		case 'e': do_snprintf("%2d", time->tm_mday);
+		case 'F': do_strftime("%Y-%m-%d");
+		/* TODO: strftime: Support week-based year */
+		case 'g': do_snprintf("??");
+		case 'G': do_snprintf("????");
+		case 'h': do_strftime("%b");
+		case 'H': do_snprintf("%02d", time->tm_hour);
+		case 'I': do_snprintf("%02d", (time->tm_hour+11)%12 + 1);
+		case 'j': do_snprintf("%03d", time->tm_yday + 1);
+		case 'm': do_snprintf("%02d", time->tm_mon + 1);
+		case 'M': do_snprintf("%02d", time->tm_min);
+		case 'n': do_snprintf("\n");
+		case 'p': do_snprintf(time->tm_hour < 12 ? "AM" : "PM");
+		case 'r': do_strftime("%I:%M:%S %p");
+		case 'R': do_strftime("%H:%M");
+		case 'S': do_snprintf("%02d", time->tm_sec);
+		case 't': do_snprintf("\t");
+		case 'T': do_strftime("%H:%M:%S");
+		case 'u': do_snprintf("%d", (time->tm_wday+6) % 7 + 1);
+		/* TODO: strftime: Support week number */
+		case 'U': do_snprintf("??");
+		case 'V': do_snprintf("??");
+		case 'w': do_snprintf("%d", time->tm_wday);
+		case 'W': do_snprintf("??");
+		case 'x': do_strftime("%m/%d/%y");
+		case 'X': do_strftime("%T");
+		case 'y': do_snprintf("%02d", time->tm_year % 100);
+		case 'Y': do_snprintf("%d", time->tm_year + 1900);
+		/* TODO: strftime: Support timezones */
+		case 'z': break;
+		case 'Z': break;
+		case '%': do_snprintf("%%");
+		}
+	}
+
+	s[len] = 0;
+	return len;
+
+full:
+	s[n-1] = 0;
+	return 0;
+}

src/libc/time/target/gint/clock.c

@@ -0,0 +1,20 @@
+#include <time.h>
+#include <gint/rtc.h>
+#include <gint/defs/attributes.h>
+
+static clock_t clock_init;
+
+static clock_t clock_abs(void)
+{
+	return (CLOCKS_PER_SEC * (uint64_t)rtc_ticks()) / 128;
+}
+
+GCONSTRUCTOR static void clock_initialize(void)
+{
+	clock_init = clock_abs();
+}
+
+clock_t clock(void)
+{
+	return clock_abs() - clock_init;
+}

src/libc/time/target/gint/time.c

@@ -0,0 +1,23 @@
+#include <time.h>
+#include <gint/rtc.h>
+
+time_t time(time_t *timeptr)
+{
+	rtc_time_t rtc;
+	struct tm tm;
+	time_t calendar;
+
+	rtc_get_time(&rtc);
+	tm.tm_sec   = rtc.seconds;
+	tm.tm_min   = rtc.minutes;
+	tm.tm_hour  = rtc.hours;
+	tm.tm_mday  = rtc.month_day;
+	tm.tm_mon   = rtc.month;
+	tm.tm_year  = rtc.year - 1900;
+	tm.tm_isdst = 0;
+
+	calendar = mktime(&tm);
+	if(timeptr != NULL)
+		*timeptr = calendar;
+	return calendar;
+}

src/libc/time/timeutil.h

@@ -0,0 +1,30 @@
+#ifndef __TIMEUTIL_H__
+# define __TIMEUTIL_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <time.h>
+#include <stdbool.h>
+
+/* Check whether a given year is a leap year. */
+static inline bool isleap(int yr)
+{
+   if(!(yr % 400)) return true;
+   if(!(yr % 100)) return false;
+   return !(yr & 3);
+}
+
+/* Number of days for the given month (0..11) and year. */
+static inline int daysin(int month, int yr)
+{
+   static char count[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+   return count[month] + (month == 1 && isleap(yr));
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /*__TIMEUTIL_H__*/