Changeset c2b0e10 in mainline for uspace/lib/c/generic/time.c

Timestamp:

2012-04-23T21:42:27Z (13 years ago)

Author:

Maurizio Lombardi <m.lombardi85@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

5b3394c

Parents:

cb948777

Message:

libc: move mktime() and strftime() from libposix to libc, remove the helper functions left
unused in libposix.

File:

• uspace/lib/c/generic/time.c (modified) (4 diffs)

uspace/lib/c/generic/time.c

@@ -1 +1 @@
 /*
  * Copyright (c) 2006 Ondrej Palkovsky
+ * Copyright (c) 2011 Petr Koupy
+ * Copyright (c) 2011 Jiri Zarevucky
  * All rights reserved.
  *
@@ -43 +45 @@
 #include <ddi.h>
 #include <libc.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <ctype.h>
 
 /** Pointer to kernel shared variables with time */
@@ -50 +55 @@
         volatile sysarg_t seconds2;
 } *ktime = NULL;
+
+/* Helper functions ***********************************************************/
+
+#define HOURS_PER_DAY (24)
+#define MINS_PER_HOUR (60)
+#define SECS_PER_MIN (60)
+#define MINS_PER_DAY (MINS_PER_HOUR * HOURS_PER_DAY)
+#define SECS_PER_HOUR (SECS_PER_MIN * MINS_PER_HOUR)
+#define SECS_PER_DAY (SECS_PER_HOUR * HOURS_PER_DAY)
+
+/**
+ * Checks whether the year is a leap year.
+ *
+ * @param year Year since 1900 (e.g. for 1970, the value is 70).
+ * @return true if year is a leap year, false otherwise
+ */
+static bool _is_leap_year(time_t year)
+{
+        year += 1900;
+
+        if (year % 400 == 0)
+                return true;
+        if (year % 100 == 0)
+                return false;
+        if (year % 4 == 0)
+                return true;
+        return false;
+}
+
+/**
+ * Returns how many days there are in the given month of the given year.
+ * Note that year is only taken into account if month is February.
+ *
+ * @param year Year since 1900 (can be negative).
+ * @param mon Month of the year. 0 for January, 11 for December.
+ * @return Number of days in the specified month.
+ */
+static int _days_in_month(time_t year, time_t mon)
+{
+        assert(mon >= 0 && mon <= 11);
+
+        static int month_days[] =
+                { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+        if (mon == 1) {
+                year += 1900;
+                /* february */
+                return _is_leap_year(year) ? 29 : 28;
+        } else {
+                return month_days[mon];
+        }
+}
+
+/**
+ * For specified year, month and day of month, returns which day of that year
+ * it is.
+ *
+ * For example, given date 2011-01-03, the corresponding expression is:
+ *     _day_of_year(111, 0, 3) == 2
+ *
+ * @param year Year (year 1900 = 0, can be negative).
+ * @param mon Month (January = 0).
+ * @param mday Day of month (First day is 1).
+ * @return Day of year (First day is 0).
+ */
+static int _day_of_year(time_t year, time_t mon, time_t mday)
+{
+        static int mdays[] =
+            { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
+        static int leap_mdays[] =
+            { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335 };
+
+        return (_is_leap_year(year) ? leap_mdays[mon] : mdays[mon]) + mday - 1;
+}
+
+/**
+ * Integer division that rounds to negative infinity.
+ * Used by some functions in this file.
+ *
+ * @param op1 Dividend.
+ * @param op2 Divisor.
+ * @return Rounded quotient.
+ */
+static time_t _floor_div(time_t op1, time_t op2)
+{
+        if (op1 >= 0 || op1 % op2 == 0) {
+                return op1 / op2;
+        } else {
+                return op1 / op2 - 1;
+        }
+}
+
+/**
+ * Modulo that rounds to negative infinity.
+ * Used by some functions in this file.
+ *
+ * @param op1 Dividend.
+ * @param op2 Divisor.
+ * @return Remainder.
+ */
+static time_t _floor_mod(time_t op1, time_t op2)
+{
+        int div = _floor_div(op1, op2);
+
+        /* (a / b) * b + a % b == a */
+        /* thus, a % b == a - (a / b) * b */
+
+        int result = op1 - div * op2;
+        
+        /* Some paranoid checking to ensure I didn't make a mistake here. */
+        assert(result >= 0);
+        assert(result < op2);
+        assert(div * op2 + result == op1);
+        
+        return result;
+}
+
+/**
+ * Number of days since the Epoch.
+ * Epoch is 1970-01-01, which is also equal to day 0.
+ *
+ * @param year Year (year 1900 = 0, may be negative).
+ * @param mon Month (January = 0).
+ * @param mday Day of month (first day = 1).
+ * @return Number of days since the Epoch.
+ */
+static time_t _days_since_epoch(time_t year, time_t mon, time_t mday)
+{
+        return (year - 70) * 365 + _floor_div(year - 69, 4) -
+            _floor_div(year - 1, 100) + _floor_div(year + 299, 400) +
+            _day_of_year(year, mon, mday);
+}
+
+/**
+ * Seconds since the Epoch. see also _days_since_epoch().
+ * 
+ * @param tm Normalized broken-down time.
+ * @return Number of seconds since the epoch, not counting leap seconds.
+ */
+static time_t _secs_since_epoch(const struct tm *tm)
+{
+        return _days_since_epoch(tm->tm_year, tm->tm_mon, tm->tm_mday) *
+            SECS_PER_DAY + tm->tm_hour * SECS_PER_HOUR +
+            tm->tm_min * SECS_PER_MIN + tm->tm_sec;
+}
+
+/**
+ * Which day of week the specified date is.
+ * 
+ * @param year Year (year 1900 = 0).
+ * @param mon Month (January = 0).
+ * @param mday Day of month (first = 1).
+ * @return Day of week (Sunday = 0).
+ */
+static int _day_of_week(time_t year, time_t mon, time_t mday)
+{
+        /* 1970-01-01 is Thursday */
+        return _floor_mod((_days_since_epoch(year, mon, mday) + 4), 7);
+}
+
+/**
+ * Normalizes the broken-down time and optionally adds specified amount of
+ * seconds.
+ * 
+ * @param tm Broken-down time to normalize.
+ * @param sec_add Seconds to add.
+ * @return 0 on success, -1 on overflow
+ */
+static int _normalize_time(struct tm *tm, time_t sec_add)
+{
+        // TODO: DST correction
+
+        /* Set initial values. */
+        time_t sec = tm->tm_sec + sec_add;
+        time_t min = tm->tm_min;
+        time_t hour = tm->tm_hour;
+        time_t day = tm->tm_mday - 1;
+        time_t mon = tm->tm_mon;
+        time_t year = tm->tm_year;
+
+        /* Adjust time. */
+        min += _floor_div(sec, SECS_PER_MIN);
+        sec = _floor_mod(sec, SECS_PER_MIN);
+        hour += _floor_div(min, MINS_PER_HOUR);
+        min = _floor_mod(min, MINS_PER_HOUR);
+        day += _floor_div(hour, HOURS_PER_DAY);
+        hour = _floor_mod(hour, HOURS_PER_DAY);
+
+        /* Adjust month. */
+        year += _floor_div(mon, 12);
+        mon = _floor_mod(mon, 12);
+
+        /* Now the difficult part - days of month. */
+        
+        /* First, deal with whole cycles of 400 years = 146097 days. */
+        year += _floor_div(day, 146097) * 400;
+        day = _floor_mod(day, 146097);
+        
+        /* Then, go in one year steps. */
+        if (mon <= 1) {
+                /* January and February. */
+                while (day > 365) {
+                        day -= _is_leap_year(year) ? 366 : 365;
+                        year++;
+                }
+        } else {
+                /* Rest of the year. */
+                while (day > 365) {
+                        day -= _is_leap_year(year + 1) ? 366 : 365;
+                        year++;
+                }
+        }
+        
+        /* Finally, finish it off month per month. */
+        while (day >= _days_in_month(year, mon)) {
+                day -= _days_in_month(year, mon);
+                mon++;
+                if (mon >= 12) {
+                        mon -= 12;
+                        year++;
+                }
+        }
+        
+        /* Calculate the remaining two fields. */
+        tm->tm_yday = _day_of_year(year, mon, day + 1);
+        tm->tm_wday = _day_of_week(year, mon, day + 1);
+        
+        /* And put the values back to the struct. */
+        tm->tm_sec = (int) sec;
+        tm->tm_min = (int) min;
+        tm->tm_hour = (int) hour;
+        tm->tm_mday = (int) day + 1;
+        tm->tm_mon = (int) mon;
+        
+        /* Casts to work around libc brain-damage. */
+        if (year > ((int)INT_MAX) || year < ((int)INT_MIN)) {
+                tm->tm_year = (year < 0) ? ((int)INT_MIN) : ((int)INT_MAX);
+                return -1;
+        }
+        
+        tm->tm_year = (int) year;
+        return 0;
+}
+
+/**
+ * Which day the week-based year starts on, relative to the first calendar day.
+ * E.g. if the year starts on December 31st, the return value is -1.
+ *
+ * @param Year since 1900.
+ * @return Offset of week-based year relative to calendar year.
+ */
+static int _wbyear_offset(int year)
+{
+        int start_wday = _day_of_week(year, 0, 1);
+        return _floor_mod(4 - start_wday, 7) - 3;
+}
+
+/**
+ * Returns week-based year of the specified time.
+ *
+ * @param tm Normalized broken-down time.
+ * @return Week-based year.
+ */
+static int _wbyear(const struct tm *tm)
+{
+        int day = tm->tm_yday - _wbyear_offset(tm->tm_year);
+        if (day < 0) {
+                /* Last week of previous year. */
+                return tm->tm_year - 1;
+        }
+        if (day > 364 + _is_leap_year(tm->tm_year)) {
+                /* First week of next year. */
+                return tm->tm_year + 1;
+        }
+        /* All the other days are in the calendar year. */
+        return tm->tm_year;
+}
+
+/**
+ * Week number of the year, assuming weeks start on sunday.
+ * The first Sunday of January is the first day of week 1;
+ * days in the new year before this are in week 0.
+ *
+ * @param tm Normalized broken-down time.
+ * @return The week number (0 - 53).
+ */
+static int _sun_week_number(const struct tm *tm)
+{
+        int first_day = (7 - _day_of_week(tm->tm_year, 0, 1)) % 7;
+        return (tm->tm_yday - first_day + 7) / 7;
+}
+
+/**
+ * Week number of the year, assuming weeks start on monday.
+ * If the week containing January 1st has four or more days in the new year,
+ * then it is considered week 1. Otherwise, it is the last week of the previous
+ * year, and the next week is week 1. Both January 4th and the first Thursday
+ * of January are always in week 1.
+ *
+ * @param tm Normalized broken-down time.
+ * @return The week number (1 - 53).
+ */
+static int _iso_week_number(const struct tm *tm)
+{
+        int day = tm->tm_yday - _wbyear_offset(tm->tm_year);
+        if (day < 0) {
+                /* Last week of previous year. */
+                return 53;
+        }
+        if (day > 364 + _is_leap_year(tm->tm_year)) {
+                /* First week of next year. */
+                return 1;
+        }
+        /* All the other days give correct answer. */
+        return (day / 7 + 1);
+}
+
+/**
+ * Week number of the year, assuming weeks start on monday.
+ * The first Monday of January is the first day of week 1;
+ * days in the new year before this are in week 0. 
+ *
+ * @param tm Normalized broken-down time.
+ * @return The week number (0 - 53).
+ */
+static int _mon_week_number(const struct tm *tm)
+{
+        int first_day = (1 - _day_of_week(tm->tm_year, 0, 1)) % 7;
+        return (tm->tm_yday - first_day + 7) / 7;
+}
+
+/******************************************************************************/
+
 
 /** Add microseconds to given timeval.
@@ -228 +566 @@
 }
 
+/**
+ * This function first normalizes the provided broken-down time
+ * (moves all values to their proper bounds) and then tries to
+ * calculate the appropriate time_t representation.
+ *
+ * @param tm Broken-down time.
+ * @return time_t representation of the time, undefined value on overflow.
+ */
+time_t mktime(struct tm *tm)
+{
+        // TODO: take DST flag into account
+        // TODO: detect overflow
+
+        _normalize_time(tm, 0);
+        return _secs_since_epoch(tm);
+}
+
+/**
+ * Convert time and date to a string, based on a specified format and
+ * current locale.
+ * 
+ * @param s Buffer to write string to.
+ * @param maxsize Size of the buffer.
+ * @param format Format of the output.
+ * @param tm Broken-down time to format.
+ * @return Number of bytes written.
+ */
+size_t strftime(char *restrict s, size_t maxsize,
+    const char *restrict format, const struct tm *restrict tm)
+{
+        assert(s != NULL);
+        assert(format != NULL);
+        assert(tm != NULL);
+
+        // TODO: use locale
+        static const char *wday_abbr[] = {
+                "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+        };
+        static const char *wday[] = {
+                "Sunday", "Monday", "Tuesday", "Wednesday",
+                "Thursday", "Friday", "Saturday"
+        };
+        static const char *mon_abbr[] = {
+                "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+                "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+        };
+        static const char *mon[] = {
+                "January", "February", "March", "April", "May", "June", "July",
+                "August", "September", "October", "November", "December"
+        };
+        
+        if (maxsize < 1) {
+                return 0;
+        }
+        
+        char *ptr = s;
+        size_t consumed;
+        size_t remaining = maxsize;
+        
+        #define append(...) { \
+                /* FIXME: this requires POSIX-correct snprintf */ \
+                /*        otherwise it won't work with non-ascii chars */ \
+                consumed = snprintf(ptr, remaining, __VA_ARGS__); \
+                if (consumed >= remaining) { \
+                        return 0; \
+                } \
+                ptr += consumed; \
+                remaining -= consumed; \
+        }
+        
+        #define recurse(fmt) { \
+                consumed = strftime(ptr, remaining, fmt, tm); \
+                if (consumed == 0) { \
+                        return 0; \
+                } \
+                ptr += consumed; \
+                remaining -= consumed; \
+        }
+        
+        #define TO_12H(hour) (((hour) > 12) ? ((hour) - 12) : \
+            (((hour) == 0) ? 12 : (hour)))
+        
+        while (*format != '\0') {
+                if (*format != '%') {
+                        append("%c", *format);
+                        format++;
+                        continue;
+                }
+                
+                format++;
+                if (*format == '0' || *format == '+') {
+                        // TODO: padding
+                        format++;
+                }
+                while (isdigit(*format)) {
+                        // TODO: padding
+                        format++;
+                }
+                if (*format == 'O' || *format == 'E') {
+                        // TODO: locale's alternative format
+                        format++;
+                }
+                
+                switch (*format) {
+                case 'a':
+                        append("%s", wday_abbr[tm->tm_wday]); break;
+                case 'A':
+                        append("%s", wday[tm->tm_wday]); break;
+                case 'b':
+                        append("%s", mon_abbr[tm->tm_mon]); break;
+                case 'B':
+                        append("%s", mon[tm->tm_mon]); break;
+                case 'c':
+                        // TODO: locale-specific datetime format
+                        recurse("%Y-%m-%d %H:%M:%S"); break;
+                case 'C':
+                        append("%02d", (1900 + tm->tm_year) / 100); break;
+                case 'd':
+                        append("%02d", tm->tm_mday); break;
+                case 'D':
+                        recurse("%m/%d/%y"); break;
+                case 'e':
+                        append("%2d", tm->tm_mday); break;
+                case 'F':
+                        recurse("%+4Y-%m-%d"); break;
+                case 'g':
+                        append("%02d", _wbyear(tm) % 100); break;
+                case 'G':
+                        append("%d", _wbyear(tm)); break;
+                case 'h':
+                        recurse("%b"); break;
+                case 'H':
+                        append("%02d", tm->tm_hour); break;
+                case 'I':
+                        append("%02d", TO_12H(tm->tm_hour)); break;
+                case 'j':
+                        append("%03d", tm->tm_yday); break;
+                case 'k':
+                        append("%2d", tm->tm_hour); break;
+                case 'l':
+                        append("%2d", TO_12H(tm->tm_hour)); break;
+                case 'm':
+                        append("%02d", tm->tm_mon); break;
+                case 'M':
+                        append("%02d", tm->tm_min); break;
+                case 'n':
+                        append("\n"); break;
+                case 'p':
+                        append("%s", tm->tm_hour < 12 ? "AM" : "PM"); break;
+                case 'P':
+                        append("%s", tm->tm_hour < 12 ? "am" : "PM"); break;
+                case 'r':
+                        recurse("%I:%M:%S %p"); break;
+                case 'R':
+                        recurse("%H:%M"); break;
+                case 's':
+                        append("%ld", _secs_since_epoch(tm)); break;
+                case 'S':
+                        append("%02d", tm->tm_sec); break;
+                case 't':
+                        append("\t"); break;
+                case 'T':
+                        recurse("%H:%M:%S"); break;
+                case 'u':
+                        append("%d", (tm->tm_wday == 0) ? 7 : tm->tm_wday);
+                        break;
+                case 'U':
+                        append("%02d", _sun_week_number(tm)); break;
+                case 'V':
+                        append("%02d", _iso_week_number(tm)); break;
+                case 'w':
+                        append("%d", tm->tm_wday); break;
+                case 'W':
+                        append("%02d", _mon_week_number(tm)); break;
+                case 'x':
+                        // TODO: locale-specific date format
+                        recurse("%Y-%m-%d"); break;
+                case 'X':
+                        // TODO: locale-specific time format
+                        recurse("%H:%M:%S"); break;
+                case 'y':
+                        append("%02d", tm->tm_year % 100); break;
+                case 'Y':
+                        append("%d", 1900 + tm->tm_year); break;
+                case 'z':
+                        // TODO: timezone
+                        break;
+                case 'Z':
+                        // TODO: timezone
+                        break;
+                case '%':
+                        append("%%");
+                        break;
+                default:
+                        /* Invalid specifier, print verbatim. */
+                        while (*format != '%') {
+                                format--;
+                        }
+                        append("%%");
+                        break;
+                }
+                format++;
+        }
+        
+        #undef append
+        #undef recurse
+        
+        return maxsize - remaining;
+}
+
+
 /** @}
  */