boot/freeldr/freeldr/arch/i386/pcrtc.c

   1 /* $Id$
   2  *
   3  *  FreeLoader
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include <freeldr.h>
  21
  22 #define BCD_INT(bcd) (((bcd & 0xf0) >> 4) * 10 + (bcd &0x0f))
  23
  24 TIMEINFO*
  25 PcGetTime(VOID)
  26 {
  27     static TIMEINFO TimeInfo;
  28     REGS Regs;
  29
  30     /* Some BIOSes, such as the 1998/07/25 system ROM
  31      * in the Compaq Deskpro EP/SB, leave CF unchanged
  32      * if successful, so CF should be cleared before
  33      * calling this function. */
  34     __writeeflags(__readeflags() & ~EFLAGS_CF);
  35
  36     /* Int 1Ah AH=04h
  37      * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
  38      *
  39      * AH = 04h
  40      * CF clear to avoid bug
  41      * Return:
  42      * CF clear if successful
  43      * CH = century (BCD)
  44      * CL = year (BCD)
  45      * DH = month (BCD)
  46      * DL = day (BCD)
  47      * CF set on error
  48      */
  49     Regs.b.ah = 0x04;
  50     Int386(0x1A, &Regs, &Regs);
  51
  52     TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
  53     TimeInfo.Month = BCD_INT(Regs.b.dh);
  54     TimeInfo.Day = BCD_INT(Regs.b.dl);
  55
  56     /* Some BIOSes leave CF unchanged if successful,
  57      * so CF should be cleared before calling this function. */
  58     __writeeflags(__readeflags() & ~EFLAGS_CF);
  59
  60     /* Int 1Ah AH=02h
  61      * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
  62      *
  63      * AH = 02h
  64      * CF clear to avoid bug
  65      * Return:
  66      * CF clear if successful
  67      * CH = hour (BCD)
  68      * CL = minutes (BCD)
  69      * DH = seconds (BCD)
  70      * DL = daylight savings flag (00h standard time, 01h daylight time)
  71      * CF set on error (i.e. clock not running or in middle of update)
  72      */
  73     Regs.b.ah = 0x02;
  74     Int386(0x1A, &Regs, &Regs);
  75
  76     TimeInfo.Hour = BCD_INT(Regs.b.ch);
  77     TimeInfo.Minute = BCD_INT(Regs.b.cl);
  78     TimeInfo.Second = BCD_INT(Regs.b.dh);
  79
  80     return &TimeInfo;
  81 }
  82
  83 /* EOF */