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 #include "arch.h"
  22 #include "machine.h"
  23 #include "machpc.h"
  24
  25 #define BCD_INT(bcd) (((bcd & 0xf0) >> 4) * 10 + (bcd &0x0f))
  26
  27 VOID
  28 PcRTCGetCurrentDateTime(PU32 Year, PU32 Month, PU32 Day, PU32 Hour, PU32 Minute, PU32 Second)
  29 {
  30   REGS Regs;
  31
  32   if (NULL != Year || NULL != Month || NULL != Day)
  33     {
  34       /* Some BIOSes, such es the 1998/07/25 system ROM
  35        * in the Compaq Deskpro EP/SB, leave CF unchanged
  36        * if successful, so CF should be cleared before
  37        * calling this function. */
  38       __asm__ ("clc");
  39
  40       /* Int 1Ah AH=04h
  41        * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
  42        *
  43        * AH = 04h
  44        * CF clear to avoid bug
  45        * Return:
  46        * CF clear if successful
  47        * CH = century (BCD)
  48        * CL = year (BCD)
  49        * DH = month (BCD)
  50        * DL = day (BCD)
  51        * CF set on error
  52        */
  53       Regs.b.ah = 0x04;
  54       Int386(0x1A, &Regs, &Regs);
  55
  56       if (NULL != Year)
  57         {
  58           *Year = 100 * BCD_INT(Regs.b.cl) + BCD_INT(Regs.b.ch);
  59         }
  60       if (NULL != Month)
  61         {
  62           *Month = BCD_INT(Regs.b.dh);
  63         }
  64       if (NULL != Day)
  65         {
  66           *Day = BCD_INT(Regs.b.dl);
  67         }
  68     }
  69
  70   if (NULL != Hour || NULL != Minute || NULL != Second)
  71     {
  72       /* Some BIOSes leave CF unchanged if successful,
  73        * so CF should be cleared before calling this function. */
  74       __asm__ ("clc");
  75
  76       /* Int 1Ah AH=02h
  77        * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
  78        *
  79        * AH = 02h
  80        * CF clear to avoid bug
  81        * Return:
  82        * CF clear if successful
  83        * CH = hour (BCD)
  84        * CL = minutes (BCD)
  85        * DH = seconds (BCD)
  86        * DL = daylight savings flag (00h standard time, 01h daylight time)
  87        * CF set on error (i.e. clock not running or in middle of update)
  88        */
  89       Regs.b.ah = 0x02;
  90       Int386(0x1A, &Regs, &Regs);
  91
  92       if (NULL != Hour)
  93         {
  94           *Hour = BCD_INT(Regs.b.ch);
  95         }
  96       if (NULL != Minute)
  97         {
  98           *Minute = BCD_INT(Regs.b.cl);
  99         }
 100       if (NULL != Second)
 101         {
 102           *Second = BCD_INT(Regs.b.dh);
 103         }
 104     }
 105 }
 106
 107 /* EOF */