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libs/libc/time/strftime: complete the strftime implementation

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1. make the strftime implementation can pass the
ltp/open_posix_testsuite/strftime/1-1 testcase
2. the modification are referred to https://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html

Signed-off-by: guoshichao <guoshichao@xiaomi.com>
This commit is contained in:
guoshichao 2023-06-13 13:54:18 +08:00 committed by Xiang Xiao
parent a40f07640f
commit 083c11ef1a
1 changed files with 253 additions and 0 deletions
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253
libs/libc/time/lib_strftime.c
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@ -25,6 +25,7 @@
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <stdio.h>
#include <debug.h>
@ -81,6 +82,115 @@ static const char * const g_monthname[12] =
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: is_leap
*
* Description:
* determine if the given year is a leap year or not
*
* Input Parameters:
* year - a year value
*
* Returnd value:
* true if current is leap year, false is not a leap year
*/
static bool is_leap(int year)
{
return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}
/****************************************************************************
* Name: get_week_num
*
* Description:
* get the week number in a year based on iso8601 standard
*
* Input Parameters:
* time - the specified time
*
* Returnd value:
* the week numer in a year
*/
static int get_week_num(FAR const struct tm *time)
{
/* calculate the total week number in a year */
int week = (time->tm_yday + DAYSPERWEEK -
(time->tm_wday + 6) % DAYSPERWEEK) / DAYSPERWEEK;
/* if xxxx-1-1 is just passed 1-3 days after Monday
* then the previous week will calculated into this year
*/
if ((time->tm_wday + 371 - time->tm_yday - 2) % DAYSPERWEEK <= 2)
{
week++;
}
if (week == 0)
{
week = 52;
/* if xxxx-12-31 is Thursday or Friday, and the previous year is
* leap year, then the previous year has 53 weeks
*/
int dec31 = (time->tm_wday + DAYSPERWEEK - time->tm_yday - 1)
% DAYSPERWEEK;
if (dec31 == TM_THURSDAY ||
(dec31 == TM_FRIDAY && is_leap(time->tm_year % 400 - 1)))
{
week++;
}
}
else if (week == 53)
{
/* If xxxx-1.1 is not a Thursday, and not a Wednesday of a leap year,
* then this year has only 52 weeks
*/
int jan1 = (time->tm_wday + 371 - time->tm_yday) % DAYSPERWEEK;
if (jan1 != TM_THURSDAY &&
(jan1 != TM_WEDNESDAY || !is_leap(time->tm_year)))
{
week = 1;
}
}
return week;
}
/****************************************************************************
* Name: get_week_year
*
* Description:
* get the week year based on iso8601 standard
*
* Input Parameters:
* time - the specified time
*
* Returnd value:
* the year that calculated based on week number
*/
static int get_week_year(FAR const struct tm *time)
{
int week_num = get_week_num(time);
int week_year = time->tm_year + TM_YEAR_BASE;
if (time->tm_yday < 3 && week_num != 1)
{
week_year--;
}
else if (time->tm_yday > 360 && week_num == 1)
{
week_year++;
}
return week_year;
}
/****************************************************************************
* Public Functions
****************************************************************************/
@ -106,6 +216,10 @@ static const char * const g_monthname[12] =
* %d The day of the month as a decimal number (range 01 to 31).
* %e Like %d, the day of the month as a decimal number, but a leading
* zero is replaced by a space.
* %F The full date format but with no time fields
* %g The last 2 digits of the week-based year as a decimal number
* [00,99]
* %G The full version of %g, display the full year value
* %h Equivalent to %b. (SU)
* %H The hour as a decimal number using a 24-hour clock
* (range 00 to 23).
@ -124,14 +238,25 @@ static const char * const g_monthname[12] =
* as "PM" and midnight as "AM".
* %P Like %p but in lowercase: "am" or "pm" or a corresponding string
* for the current locale. (GNU)
* %r The time in a.m. and p.m. notation
* %R The time in 24-hour notation ( %H : %M ).
* %s The number of seconds since the Epoch, that is, since 1970-01-01
* 00:00:00 UTC. (TZ)
* %S The second as a decimal number (range 00 to 60). (The range is
* up to 60 to allow for occasional leap seconds.)
* %t A tab character. (SU)
* %u The weekday as a decimal number [1,7], with 1 representing
* Monday.
* %U The week number of the year as a decimal number [00,53].
* %V The week number of the year
* %w The weekday as a decimal number (range 0 to 6).
* %W The week number of the year as a decimal number [00,53].
* %x The locale's appropriate date representation, but without time.
* %X The locale's appropriate time representation, but without date.
* %y The year as a decimal number without a century (range 00 to 99).
* %Y The year as a decimal number including the century.
* %z The timezone name or abbreviation, or by no bytes if no timezone
* information exists.
* %% A literal '%' character.
*
* Returned Value:
@ -251,6 +376,33 @@ size_t strftime(FAR char *s, size_t max, FAR const char *format,
}
break;
/* %F: ISO 8601 date format: "%Y-%m-%d" */
case 'F':
{
len = snprintf(dest, chleft, "%04d-%02d-%02d",
tm->tm_year + TM_YEAR_BASE, tm->tm_mon,
tm->tm_mday);
}
break;
/* %g: 2-digit year version of %G, (00-99) */
case 'g':
{
value = get_week_year(tm) % 100;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %G: ISO 8601 week based year */
case 'G':
{
len = snprintf(dest, chleft, "%04d", get_week_year(tm));
}
break;
/* %H: The hour as a decimal number using a 24-hour clock
* (range 00 to 23).
*/
@ -369,6 +521,28 @@ size_t strftime(FAR char *s, size_t max, FAR const char *format,
}
break;
/* %r: 12-hour clock time */
case 'r':
{
if (tm->tm_hour >= 12)
{
str = "pm";
}
else
{
str = "am";
}
value = tm->tm_hour == 12 ?
tm->tm_hour == 12 :
tm->tm_hour % (HOURSPERDAY / 2);
len = snprintf(dest, chleft, "%02d:%02d:%02d %s",
value, tm->tm_min, tm->tm_sec, str);
}
break;
/* %R: Shortcut for %H:%M. */
case 'R':
@ -418,6 +592,39 @@ size_t strftime(FAR char *s, size_t max, FAR const char *format,
}
break;
/* %u: The day of the week as a decimal, (1-7). Monday being 1,
* Sunday being 0.
*/
case 'u':
{
value = tm->tm_wday == 0 ? 7 : tm->tm_wday;
len = snprintf(dest, chleft, "%d", value);
}
break;
/* %U: week number of the current year as a decimal number,
* (00-53). Starting with the first Sunday as the first day
* of week 01.
*/
case 'U':
{
value = (tm->tm_yday + DAYSPERWEEK - tm->tm_wday)
/ DAYSPERWEEK;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %V: ISO 8601 week number */
case 'V':
{
value = get_week_num(tm);
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %w: The weekday as a decimal number (range 0 to 6). */
case 'w':
@ -426,6 +633,39 @@ size_t strftime(FAR char *s, size_t max, FAR const char *format,
}
break;
/* %W: Week number of the current year as a decimal number,
* (00-53). Starting with the first Monday as the first day
* of week 01.
*/
case 'W':
{
value = (tm->tm_yday + DAYSPERWEEK -
(tm->tm_wday + 6) % DAYSPERWEEK)
/ DAYSPERWEEK;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %x Locale date without time */
case 'x':
{
len = snprintf(dest, chleft, "%02d/%02d/%04d",
tm->tm_mon, tm->tm_mday,
tm->tm_year + TM_YEAR_BASE);
}
break;
/* %X: Locale time without date */
case 'X':
{
len = snprintf(dest, chleft, "%02d:%02d:%02d",
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
break;
/* %y: The year as a decimal number without a century
* (range 00 to 99).
*/
@ -445,6 +685,19 @@ size_t strftime(FAR char *s, size_t max, FAR const char *format,
}
break;
/* %z: Numeric timezone as hour and minute offset from UTC
* "+hhmm" or "-hhmm"
*/
case 'z':
{
int hour = tm->tm_gmtoff / 3600;
int min = tm->tm_gmtoff % 3600 / 60;
int utc_val = hour * 100 + min;
len = snprintf(dest, chleft, "+%04d", utc_val);
}
break;
/* %%: A literal '%' character. */
case '%':