reactos/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
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 #include <freeldr.h>
  21
  22 #define BCD_INT(bcd) (((bcd & 0xf0) >> 4) * 10 + (bcd &0x0f))
  23
  24 VOID
  25 PcRTCGetCurrentDateTime(PULONG Year, PULONG Month, PULONG Day, PULONG Hour, PULONG Minute, PULONG Second)
  26 {
  27   REGS Regs;
  28
  29   if (NULL != Year || NULL != Month || NULL != Day)
  30     {
  31       /* Some BIOSes, such es the 1998/07/25 system ROM
  32        * in the Compaq Deskpro EP/SB, leave CF unchanged
  33        * if successful, so CF should be cleared before
  34        * calling this function. */
  35       __asm__ ("clc");
  36
  37       /* Int 1Ah AH=04h
  38        * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
  39        *
  40        * AH = 04h
  41        * CF clear to avoid bug
  42        * Return:
  43        * CF clear if successful
  44        * CH = century (BCD)
  45        * CL = year (BCD)
  46        * DH = month (BCD)
  47        * DL = day (BCD)
  48        * CF set on error
  49        */
  50       Regs.b.ah = 0x04;
  51       Int386(0x1A, &Regs, &Regs);
  52
  53       if (NULL != Year)
  54         {
  55           *Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
  56         }
  57       if (NULL != Month)
  58         {
  59           *Month = BCD_INT(Regs.b.dh);
  60         }
  61       if (NULL != Day)
  62         {
  63           *Day = BCD_INT(Regs.b.dl);
  64         }
  65     }
  66
  67   if (NULL != Hour || NULL != Minute || NULL != Second)
  68     {
  69       /* Some BIOSes leave CF unchanged if successful,
  70        * so CF should be cleared before calling this function. */
  71       __asm__ ("clc");
  72
  73       /* Int 1Ah AH=02h
  74        * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
  75        *
  76        * AH = 02h
  77        * CF clear to avoid bug
  78        * Return:
  79        * CF clear if successful
  80        * CH = hour (BCD)
  81        * CL = minutes (BCD)
  82        * DH = seconds (BCD)
  83        * DL = daylight savings flag (00h standard time, 01h daylight time)
  84        * CF set on error (i.e. clock not running or in middle of update)
  85        */
  86       Regs.b.ah = 0x02;
  87       Int386(0x1A, &Regs, &Regs);
  88
  89       if (NULL != Hour)
  90         {
  91           *Hour = BCD_INT(Regs.b.ch);
  92         }
  93       if (NULL != Minute)
  94         {
  95           *Minute = BCD_INT(Regs.b.cl);
  96         }
  97       if (NULL != Second)
  98         {
  99           *Second = BCD_INT(Regs.b.dh);
 100         }
 101     }
 102 }
 103
 104 /* EOF */