pcrtc.c File Reference

#include <freeldr.h>

Include dependency graph for pcrtc.c:

Go to the source code of this file.

Functions
static UCHAR	BCD_INT (_In_ UCHAR Bcd)
TIMEINFO *	PcGetTime (VOID)

Function Documentation

BCD_INT()

static UCHAR BCD_INT ( _In_ UCHAR  Bcd )

static

Definition at line 23 of file pcrtc.c.

{
    return ((Bcd & 0xF0) >> 4) * 10 + (Bcd & 0x0F);
}

Referenced by PcGetTime().

PcGetTime()

TIMEINFO * PcGetTime

(

VOID

)

Definition at line 30 of file pcrtc.c.

{
    static TIMEINFO TimeInfo;
    REGS Regs;
 
    for (;;)
    {
        /* Some BIOSes, such as the 1998/07/25 system ROM
         * in the Compaq Deskpro EP/SB, leave CF unchanged
         * if successful, so CF should be cleared before
         * calling this function. */
        Regs.x.eflags = 0;
//        __writeeflags(__readeflags() & ~EFLAGS_CF);
 
        /* Int 1Ah AH=04h
         * TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
         *
         * AH = 04h
         * CF clear to avoid bug
         * Return:
         * CF clear if successful
         * CH = century (BCD)
         * CL = year (BCD)
         * DH = month (BCD)
         * DL = day (BCD)
         * CF set on error
         */
        Regs.b.ah = 0x04;
        Int386(0x1A, &Regs, &Regs);
 
        if (!INT386_SUCCESS(Regs)) continue;
 
        TimeInfo.Year = 100 * BCD_INT(Regs.b.ch) + BCD_INT(Regs.b.cl);
        TimeInfo.Month = BCD_INT(Regs.b.dh);
        TimeInfo.Day = BCD_INT(Regs.b.dl);
 
        /* Some BIOSes leave CF unchanged if successful,
         * so CF should be cleared before calling this function. */
        Regs.x.eflags = 0;
//        __writeeflags(__readeflags() & ~EFLAGS_CF);
 
        /* Int 1Ah AH=02h
         * TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
         *
         * AH = 02h
         * CF clear to avoid bug
         * Return:
         * CF clear if successful
         * CH = hour (BCD)
         * CL = minutes (BCD)
         * DH = seconds (BCD)
         * DL = daylight savings flag (00h standard time, 01h daylight time)
         * CF set on error (i.e. clock not running or in middle of update)
         */
        Regs.b.ah = 0x02;
        Int386(0x1A, &Regs, &Regs);
 
        if (!INT386_SUCCESS(Regs)) continue;
 
        TimeInfo.Hour = BCD_INT(Regs.b.ch);
        TimeInfo.Minute = BCD_INT(Regs.b.cl);
        TimeInfo.Second = BCD_INT(Regs.b.dh);
 
        break;
    }
    return &TimeInfo;
}

Referenced by MachInit().