rom/filesys/fat/date.c

   1 /*
   2  * fat-handler - FAT12/16/32 filesystem handler
   3  *
   4  * Copyright © 2006 Marek Szyprowski
   5  * Copyright © 2007-2015 The AROS Development Team
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the same terms as AROS itself.
   9  *
  10  * $Id$
  11  */
  12
  13 #include <proto/utility.h>
  14
  15 #include "fat_fs.h"
  16 #include "fat_protos.h"
  17
  18 #define DEBUG DEBUG_MISC
  19 #include "debug.h"
  20
  21 void ConvertFATDate(UWORD date, UWORD time, struct DateStamp *ds,
  22     struct Globals *glob)
  23 {
  24     ULONG year, month, day, hours, mins, secs;
  25     struct ClockData clock_data;
  26
  27     /* Date bits: yyyy yyym mmmd dddd */
  28     year = (date & 0xfe00) >> 9;    /* Bits 15-9 */
  29     month = (date & 0x01e0) >> 5;   /* bits 8-5 */
  30     day = date & 0x001f;            /* Bits 4-0 */
  31
  32     /* Time bits: hhhh hmmm mmms ssss */
  33     hours = (time & 0xf800) >> 11;  /* Bits 15-11 */
  34     mins = (time & 0x07e0) >> 5;    /* Bits 10-5 */
  35     secs = time & 0x001f;           /* Bits 4-0 */
  36
  37     D(bug("[fat] converting fat date: year %d month %d day %d hours %d"
  38         " mins %d secs %d\n", year, month, day, hours, mins, secs));
  39
  40     if (month < 1 || month > 12 || day < 1 || day > 31 || hours > 23 ||
  41         mins > 59 || secs > 29)
  42     {
  43         D(bug("[fat] invalid fat date: using 01-01-1978 instead\n"));
  44         secs = 0;
  45     }
  46     else
  47     {
  48         clock_data.year = 1980 + year;
  49         clock_data.month = month;
  50         clock_data.mday = day;
  51         clock_data.hour = hours;
  52         clock_data.min = mins;
  53         clock_data.sec = secs << 1;
  54         secs = Date2Amiga(&clock_data);
  55     }
  56
  57     /* Calculate days since 1978-01-01 (DOS epoch) */
  58     ds->ds_Days = secs / (60 * 60 * 24);
  59
  60     /* Minutes since midnight */
  61     ds->ds_Minute = secs / 60 % (24 * 60);
  62
  63     /* 1/50 sec ticks since last minute */
  64     ds->ds_Tick = secs % 60 * TICKS_PER_SECOND;
  65
  66     D(bug("[fat] converted fat date: days %ld minutes %ld ticks %ld\n",
  67         ds->ds_Days, ds->ds_Minute, ds->ds_Tick));
  68 }
  69
  70 void ConvertDOSDate(struct DateStamp *ds, UWORD * date, UWORD * time,
  71     struct Globals *glob)
  72 {
  73     ULONG year, month, day, hours, mins, secs;
  74     struct ClockData clock_data;
  75
  76     /* Convert datestamp to seconds since 1978 */
  77     secs = ds->ds_Days * 60 * 60 * 24 + ds->ds_Minute * 60
  78         + ds->ds_Tick / TICKS_PER_SECOND;
  79
  80     /* Round up to next even second because of FAT's two-second granularity */
  81     secs = (secs & ~1) + 2;
  82
  83     /* Convert seconds since 1978 to calendar/time data */
  84     Amiga2Date(secs, &clock_data);
  85
  86     /* Get values used in FAT dates */
  87     year = clock_data.year - 1980;
  88     month = clock_data.month - 0;
  89     day = clock_data.mday;
  90     hours = clock_data.hour;
  91     mins = clock_data.min;
  92     secs = clock_data.sec >> 1;
  93
  94     /* All that remains is to bit-encode the whole lot */
  95
  96     /* Date bits: yyyy yyym mmmd dddd */
  97     *date = (((ULONG) year) << 9) | (((ULONG) month) << 5) | day;
  98
  99     /* Time bits: hhhh hmmm mmms ssss */
 100     *time = (((ULONG) hours) << 11) | (((ULONG) mins) << 5) | secs;
 101 }
 102