Category : Files from Magazines
Archive : FEB91.ZIP
Filename : 2N02025A
Output of file : 2N02025A contained in archive : FEB91.ZIP
#include
#include "defs.h"
extern int DOS_Extender;
#ifdef __HIGHC__
typedef _far void (*ISRH)(void);
#else
typedef void (_far *ISRH)(void);
#endif
typedef struct isr_struct
{
ULONG realvector;
ISRH handler;
} ISR;
ISR OldTimer, NewTimer, OldInt90, NewInt90;
void HookTimer(void);
void UnHookTimer(void);
void GetISR(USHORT intnum, ISR *OldISR);
void SetISR(USHORT intnum, ISR *NewISR, UINT PharlapStrategy);
#if defined(_I386) || defined(_I486) || defined(__386__)
extern void NewTimerISR(void);
#else
extern void _far NewTimerISR(void);
#endif
#define SET_ISR 0x2500
#define GET_ISR 0x3500
#define GET_PROT_ISRH 0x2502
#define GET_REAL_VECTOR 0x2503
#define SET_PROT_ISRH 0x2504
#define SET_REAL_VECTOR 0x2505
#define SET_PROT_ALLWAYS 0x2506
#define SET_BOTH 0x2507
#define GET_HARD_IRQ_BASE 0x250C
void HookTimer(void)
{
GetISR(0x90, &OldInt90);
GetISR(0x08, &OldTimer);
if (DOS_Extender == PHARLAP_386)
NewInt90.realvector = OldTimer.realvector;
else
NewInt90.handler = OldTimer.handler;
NewTimer.handler = (ISRH)NewTimerISR;
SetISR(0x90, &NewInt90, SET_REAL_VECTOR);
SetISR(0x08, &NewTimer, SET_PROT_ALLWAYS);
}
void UnHookTimer(void)
{
SetISR(0x08, &OldTimer, SET_BOTH);
SetISR(0x90, &OldInt90, SET_REAL_VECTOR);
}
void GetISR(USHORT intnum, ISR *OldISR)
{
union REGS regs;
struct SREGS segregs;
if (DOS_Extender == PHARLAP_386)
{
if ( intnum > 0x07 && intnum < 0x10 ) /* Hardware IRQs are remapped */
{
/*-------------------------------------------------------------*/
/* Get the interrupt vector base for IRQ0 through IRQ7 */
/* DOS maps these to interrupts 0x08 through 0x0F */
/*-------------------------------------------------------------*/
regs.x.AX = GET_HARD_IRQ_BASE;
int86(0x21, ®s, ®s); /* get IRQ0-IRQ7 base vector */
intnum += regs.h.al - 0x08; /* adjust the target intnum */
}
regs.x.CX = intnum; /*specify get interrupt vector */
regs.x.AX = GET_PROT_ISRH; /*specify protected mode handler */
segread(&segregs);
int86x(0x21, ®s, ®s, &segregs); /*get the prot handler */
FP_MAK(OldISR->handler, regs.x.BX, segregs.es);
regs.x.AX = GET_REAL_VECTOR; /*specify real mode vector */
segread(&segregs);
int86x(0x21, ®s, ®s, &segregs); /*get the real vector */
OldISR->realvector = (ULONG) regs.x.BX;
}
else /* REAL MODE or an ERGO extender */
{
regs.x.AX = GET_ISR | intnum;
segread(&segregs);
int86x(0x21, ®s, ®s, &segregs);
FP_MAK(OldISR->handler, regs.x.BX, segregs.es);
}
}
void SetISR(USHORT intnum, ISR *NewISR, UINT PharlapStrategy)
{
union REGS regs;
struct SREGS segregs;
segread(&segregs);
#if defined(_I386) || defined(_I486) || defined(__386__)
if (DOS_Extender == PHARLAP_386)
{
if ( intnum < 0x10 && intnum > 0x07 ) /* Hardware IRQs are remapped */
{
/*-------------------------------------------------------------*/
/* Get the interrupt vector base for IRQ0 through IRQ7 */
/*-------------------------------------------------------------*/
regs.x.AX = GET_HARD_IRQ_BASE;
int86(0x21, ®s, ®s); /* get the base interrupt vector */
intnum += regs.h.al - 0x08; /* adjust the target intnum */
}
regs.x.CX = intnum;
switch (PharlapStrategy)
{
case SET_PROT_ALLWAYS:
regs.x.AX = SET_PROT_ALLWAYS;
regs.x.DX = FP_OFF(NewISR->handler);/*extract ISRH offset */
segregs.ds = FP_SEG(NewISR->handler);/*extract ISRH segment*/
break;
case SET_PROT_ISRH:
regs.x.AX = SET_PROT_ISRH;
regs.x.DX = FP_OFF(NewISR->handler);/*extract ISRH offset */
segregs.ds = FP_SEG(NewISR->handler);/*extract ISRH segment*/
break;
case SET_REAL_VECTOR:
regs.x.AX = SET_REAL_VECTOR; /*specify interrupt vector replacement*/
regs.x.BX = NewISR->realvector;
break;
case SET_BOTH:
regs.x.AX = SET_BOTH;
regs.x.BX = NewISR->realvector;
regs.x.DX = FP_OFF(NewISR->handler);/*extract ISRH offset */
segregs.ds = FP_SEG(NewISR->handler);/*extract ISRH segment*/
break;
}
}
else
#endif
{ /* Real Mode or ERGO Extenders */
regs.x.AX = SET_ISR | intnum; /*specify interrupt handler*/
regs.x.DX = FP_OFF(NewISR->handler);/*extract isr offset */
segregs.ds = FP_SEG(NewISR->handler);/*extract isr segment*/
}
int86x(0x21, ®s, ®s, &segregs);
}
#ifdef __HIGHC__
#pragma Alias(NewTimerISR, "_NewTimerISR");
#endif
#ifdef __WATCOMC__
#pragma aux (OUR_C) NewTimerISR;
#endif
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