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* libc/time/mktm_r.c (_mktm_r): Optimize speed.

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Corinna Vinschen
2014-09-04 09:47:14 +00:00
parent 7d407cb678
commit 9adec6fd79
2 changed files with 38 additions and 16 deletions
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4
newlib/ChangeLog
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@@ -1,3 +1,7 @@
2014-09-04 Freddie Chopin <freddie_chopin@op.pl>
* libc/time/mktm_r.c (_mktm_r): Optimize speed.
2014-09-04 Freddie Chopin <freddie_chopin@op.pl>
* libc/time/clock.c (clock): Fix warnings about signed-unsigned

50
newlib/libc/time/mktm_r.c
View File

@@ -14,14 +14,23 @@
#include <time.h>
#include "local.h"
/* there are 97 leap years in 400-year periods */
#define DAYS_PER_400_YEARS ((400 - 97) * 365 + 97 * 366)
/* there are 24 leap years in 100-year periods */
#define DAYS_PER_100_YEARS ((100 - 24) * 365 + 24 * 366)
/* there is one leap year every 4 years */
#define DAYS_PER_4_YEARS (3 * 365 + 366)
static _CONST int mon_lengths[2][MONSPERYEAR] = {
{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
{31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
} ;
static _CONST int year_lengths[2] = {
365,
366
static _CONST int days_per_year[4] = {
365, /* 1970 or 1966 */
365, /* 1971 or 1967 */
366, /* 1972 or 1968 */
365 /* 1973 or 1969 */
} ;
struct tm *
@@ -33,6 +42,7 @@ _DEFUN (_mktm_r, (tim_p, res, is_gmtime),
long days, rem;
time_t lcltime;
int y;
int years400, years100, years4;
int yleap;
_CONST int *ip;
__tzinfo_type *tz = __gettzinfo ();
@@ -64,30 +74,38 @@ _DEFUN (_mktm_r, (tim_p, res, is_gmtime),
res->tm_wday += DAYSPERWEEK;
/* compute year & day of year */
y = EPOCH_YEAR;
if (days >= 0)
years400 = days / DAYS_PER_400_YEARS;
days -= years400 * DAYS_PER_400_YEARS;
years100 = days / DAYS_PER_100_YEARS;
days -= years100 * DAYS_PER_100_YEARS;
years4 = days / DAYS_PER_4_YEARS;
days -= years4 * DAYS_PER_4_YEARS;
y = EPOCH_YEAR + years400 * 400 + years100 * 100 + years4 * 4;
/* the value left in days is based in 1970 */
if (days < 0)
{
for (;;)
ip = &days_per_year[3];
while (days < 0)
{
yleap = isleap(y);
if (days < year_lengths[yleap])
break;
y++;
days -= year_lengths[yleap];
days += *ip--;
--y;
}
}
else
{
do
ip = &days_per_year[0];
while (days >= *ip)
{
--y;
yleap = isleap(y);
days += year_lengths[yleap];
} while (days < 0);
days -= *ip++;
++y;
}
}
res->tm_year = y - YEAR_BASE;
res->tm_yday = days;
yleap = isleap(y);
ip = mon_lengths[yleap];
for (res->tm_mon = 0; days >= ip[res->tm_mon]; ++res->tm_mon)
days -= ip[res->tm_mon];