release/src-rt/linux/linux-2.6/fs/exfat/exfat_oal.c

   1 /* Some of the source code in this file came from "linux/fs/fat/misc.c".  */
   2 /*
   3  *  linux/fs/fat/misc.c
   4  *
   5  *  Written 1992,1993 by Werner Almesberger
   6  *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
   7  *         and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
   8  */
   9
  10 /*
  11  *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
  12  *
  13  *  This program is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU General Public License
  15  *  as published by the Free Software Foundation; either version 2
  16  *  of the License, or (at your option) any later version.
  17  *
  18  *  This program is distributed in the hope that it will be useful,
  19  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  *  GNU General Public License for more details.
  22  *
  23  *  You should have received a copy of the GNU General Public License
  24  *  along with this program; if not, write to the Free Software
  25  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  26  */
  27
  28 /************************************************************************/
  29 /*                                                                      */
  30 /*  PROJECT : exFAT & FAT12/16/32 File System                           */
  31 /*  FILE    : exfat_oal.c                                               */
  32 /*  PURPOSE : exFAT OS Adaptation Layer                                 */
  33 /*            (Semaphore Functions & Real-Time Clock Functions)         */
  34 /*                                                                      */
  35 /*----------------------------------------------------------------------*/
  36 /*  NOTES                                                               */
  37 /*                                                                      */
  38 /*----------------------------------------------------------------------*/
  39 /*  REVISION HISTORY (Ver 0.9)                                          */
  40 /*                                                                      */
  41 /*  - 2010.11.15 [Joosun Hahn] : first writing                          */
  42 /*                                                                      */
  43 /************************************************************************/
  44
  45 #include <linux/semaphore.h>
  46 #include <linux/time.h>
  47
  48 #include "exfat_config.h"
  49 #include "exfat_global.h"
  50 #include "exfat_api.h"
  51 #include "exfat_oal.h"
  52
  53 /*======================================================================*/
  54 /*                                                                      */
  55 /*            SEMAPHORE FUNCTIONS                                       */
  56 /*                                                                      */
  57 /*======================================================================*/
  58
  59 DECLARE_MUTEX(z_sem);
  60
  61 INT32 sm_init(struct semaphore *sm)
  62 {
  63         sema_init(sm, 1);
  64         return(0);
  65 } /* end of sm_init */
  66
  67 INT32 sm_P(struct semaphore *sm)
  68 {
  69         down(sm);
  70         return 0;
  71 } /* end of sm_P */
  72
  73 void sm_V(struct semaphore *sm)
  74 {
  75         up(sm);
  76 } /* end of sm_V */
  77
  78
  79 /*======================================================================*/
  80 /*                                                                      */
  81 /*            REAL-TIME CLOCK FUNCTIONS                                 */
  82 /*                                                                      */
  83 /*======================================================================*/
  84
  85 extern struct timezone sys_tz;
  86
  87 /*
  88  * The epoch of FAT timestamp is 1980.
  89  *     :  bits  : value
  90  * date:  0 -  4: day    (1 -  31)
  91  * date:  5 -  8: month  (1 -  12)
  92  * date:  9 - 15: year   (0 - 127) from 1980
  93  * time:  0 -  4: sec    (0 -  29) 2sec counts
  94  * time:  5 - 10: min    (0 -  59)
  95  * time: 11 - 15: hour   (0 -  23)
  96  */
  97 #define UNIX_SECS_1980   315532800L
  98
  99 #if BITS_PER_LONG == 64
 100 #define UNIX_SECS_2108   4354819200L
 101 #endif
 102 /* days between 1.1.70 and 1.1.80 (2 leap days) */
 103 #define DAYS_DELTA_DECADE       (365 * 10 + 2)
 104 /* 120 (2100 - 1980) isn't leap year */
 105 #define NO_LEAP_YEAR_2100    (120)
 106 #define IS_LEAP_YEAR(y)  (!((y) & 3) && (y) != NO_LEAP_YEAR_2100)
 107
 108 #define SECS_PER_MIN     (60)
 109 #define SECS_PER_HOUR    (60 * SECS_PER_MIN)
 110 #define SECS_PER_DAY     (24 * SECS_PER_HOUR)
 111
 112 #define MAKE_LEAP_YEAR(leap_year, year)                         \
 113         do {                                                    \
 114                 if (unlikely(year > NO_LEAP_YEAR_2100))         \
 115                         leap_year = ((year + 3) / 4) - 1;       \
 116                 else                                            \
 117                         leap_year = ((year + 3) / 4);           \
 118         } while(0)
 119
 120 /* Linear day numbers of the respective 1sts in non-leap years. */
 121 static time_t accum_days_in_year[] = {
 122         /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 123         0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 124 };
 125
 126 TIMESTAMP_T *tm_current(TIMESTAMP_T *tp)
 127 {
 128         struct timespec ts = CURRENT_TIME_SEC;
 129         time_t second = ts.tv_sec;
 130         time_t day, leap_day, month, year;
 131
 132         second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
 133
 134         /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
 135         if (second < UNIX_SECS_1980) {
 136                 tp->sec  = 0;
 137                 tp->min  = 0;
 138                 tp->hour = 0;
 139                 tp->day  = 1;
 140                 tp->mon  = 1;
 141                 tp->year = 0;
 142                 return(tp);
 143         }
 144 #if BITS_PER_LONG == 64
 145         if (second >= UNIX_SECS_2108) {
 146                 tp->sec  = 59;
 147                 tp->min  = 59;
 148                 tp->hour = 23;
 149                 tp->day  = 31;
 150                 tp->mon  = 12;
 151                 tp->year = 127;
 152                 return(tp);
 153         }
 154 #endif
 155
 156         day = second / SECS_PER_DAY - DAYS_DELTA_DECADE;
 157         year = day / 365;
 158
 159         MAKE_LEAP_YEAR(leap_day, year);
 160         if (year * 365 + leap_day > day)
 161                 year--;
 162
 163         MAKE_LEAP_YEAR(leap_day, year);
 164
 165         day -= year * 365 + leap_day;
 166
 167         if (IS_LEAP_YEAR(year) && day == accum_days_in_year[3]) {
 168                 month = 2;
 169         } else {
 170                 if (IS_LEAP_YEAR(year) && day > accum_days_in_year[3])
 171                         day--;
 172                 for (month = 1; month < 12; month++) {
 173                         if (accum_days_in_year[month + 1] > day)
 174                                 break;
 175                 }
 176         }
 177         day -= accum_days_in_year[month];
 178
 179         tp->sec  = second % SECS_PER_MIN;
 180         tp->min  = (second / SECS_PER_MIN) % 60;
 181         tp->hour = (second / SECS_PER_HOUR) % 24;
 182         tp->day  = day + 1;
 183         tp->mon  = month;
 184         tp->year = year;
 185
 186         return(tp);
 187 } /* end of tm_current */
 188
 189 /* end of exfat_oal.c */