source/filetime.c

   1 /*
   2  filetime.c
   3  Conversion of file time and date values to various other types
   4
   5  Copyright (c) 2006 Michael "Chishm" Chisholm
   6
   7  Redistribution and use in source and binary forms, with or without modification,
   8  are permitted provided that the following conditions are met:
   9
  10   1. Redistributions of source code must retain the above copyright notice,
  11      this list of conditions and the following disclaimer.
  12   2. Redistributions in binary form must reproduce the above copyright notice,
  13      this list of conditions and the following disclaimer in the documentation and/or
  14      other materials provided with the distribution.
  15   3. The name of the author may not be used to endorse or promote products derived
  16      from this software without specific prior written permission.
  17
  18  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  19  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  20  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
  21  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  23  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  26  EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27 */
  28
  29
  30 #include <time.h>
  31 #include "filetime.h"
  32 #include "common.h"
  33
  34 #define MAX_HOUR 23
  35 #define MAX_MINUTE 59
  36 #define MAX_SECOND 59
  37
  38 #define MAX_MONTH 11
  39 #define MIN_MONTH 0
  40 #define MAX_DAY 31
  41 #define MIN_DAY 1
  42
  43 uint16_t _FAT_filetime_getTimeFromRTC (void) {
  44 #ifdef USE_RTC_TIME
  45         struct tm timeParts;
  46         time_t epochTime;
  47
  48         if (time(&epochTime) == (time_t)-1) {
  49                 return 0;
  50         }
  51         localtime_r(&epochTime, &timeParts);
  52
  53         // Check that the values are all in range.
  54         // If they are not, return 0 (no timestamp)
  55         if ((timeParts.tm_hour < 0) || (timeParts.tm_hour > MAX_HOUR))  return 0;
  56         if ((timeParts.tm_min < 0) || (timeParts.tm_min > MAX_MINUTE)) return 0;
  57         if ((timeParts.tm_sec < 0) || (timeParts.tm_sec > MAX_SECOND)) return 0;
  58
  59         return (
  60                 ((timeParts.tm_hour & 0x1F) << 11) |
  61                 ((timeParts.tm_min & 0x3F) << 5) |
  62                 ((timeParts.tm_sec >> 1) & 0x1F)
  63         );
  64 #else
  65         return 0;
  66 #endif
  67 }
  68
  69
  70 uint16_t _FAT_filetime_getDateFromRTC (void) {
  71 #ifdef USE_RTC_TIME
  72         struct tm timeParts;
  73         time_t epochTime;
  74
  75         if (time(&epochTime) == (time_t)-1) {
  76                 return 0;
  77         }
  78         localtime_r(&epochTime, &timeParts);
  79
  80         if ((timeParts.tm_mon < MIN_MONTH) || (timeParts.tm_mon > MAX_MONTH)) return 0;
  81         if ((timeParts.tm_mday < MIN_DAY) || (timeParts.tm_mday > MAX_DAY)) return 0;
  82
  83         return (
  84                 (((timeParts.tm_year - 80) & 0x7F) <<9) |       // Adjust for MS-FAT base year (1980 vs 1900 for tm_year)
  85                 (((timeParts.tm_mon + 1) & 0xF) << 5) |
  86                 (timeParts.tm_mday & 0x1F)
  87         );
  88 #else
  89         return 0;
  90 #endif
  91 }
  92
  93 time_t _FAT_filetime_to_time_t (uint16_t t, uint16_t d) {
  94         struct tm timeParts;
  95
  96         timeParts.tm_hour = t >> 11;
  97         timeParts.tm_min = (t >> 5) & 0x3F;
  98         timeParts.tm_sec = (t & 0x1F) << 1;
  99
 100         timeParts.tm_mday = d & 0x1F;
 101         timeParts.tm_mon = ((d >> 5) & 0x0F) - 1;
 102         timeParts.tm_year = (d >> 9) + 80;
 103
 104         timeParts.tm_isdst = 0;
 105
 106         return mktime(&timeParts);
 107 }