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/*
Name:
MDMA.C
Description:
Some general purpose IRQ routines
Portability:
MSDOS: BC(y) Watcom(y) DJGPP(y)
Win95: n
Os2: n
Linux: n
(y) - yes
(n) - no (not possible or not useful)
(?) - may be possible, but not tested
*/
#include <dos.h>
#include <conio.h>
#include "mirq.h"
#define OCR1 0x20 /* 8259-1 Operation control register */
#define IMR1 0x21 /* 8259-1 Mask register */
#define OCR2 0xA0 /* 8259-2 Operation control register */
#define IMR2 0xA1 /* 8259-2 Mask register */
BOOL MIrq_IsEnabled(UBYTE irqno)
/*
Returns true if the specified hardware irq is enabled.
*/
{
UBYTE imr = (irqno > 7) ? IMR2 : IMR1; /* interrupt mask register */
UBYTE msk = 1 << (irqno & 7); /* interrupt mask */
return ((inportb(imr) & msk) == 0);
}
BOOL MIrq_OnOff(UBYTE irqno, UBYTE onoff)
/*
Use to enable or disable the specified irq.
*/
{
UBYTE imr = (irqno > 7) ? IMR2 : IMR1; /* interrupt mask register */
UBYTE ocr = (irqno > 7) ? OCR2 : OCR1; /* ocr */
UBYTE msk = 1 << (irqno & 7); /* interrupt mask */
UBYTE eoi = 0x60 | (irqno & 7); /* specific end-of-interrupt */
BOOL oldstate;
/* save current setting of this irq */
oldstate = ((inportb(imr) & msk) == 0);
if (onoff) {
outportb(imr, inportb(imr) & ~msk);
outportb(ocr, eoi);
if (irqno > 7)
MIrq_OnOff(2, 1);
}
else {
outportb(imr, inportb(imr) | msk);
}
return oldstate;
}
void MIrq_EOI(UBYTE irqno)
/*
Clears the specified interrupt request at the interrupt controller.
*/
{
UBYTE ocr = (irqno > 7) ? OCR2 : OCR1; /* ocr */
UBYTE eoi = 0x60 | (irqno & 7); /* specific end-of-interrupt */
outportb(ocr, eoi);
if (irqno > 7)
outportb(OCR1, 0x20);
}
PVI MIrq_SetHandler(UBYTE irqno, PVI handler)
{
#ifdef __DJGPP__
_go32_dpmi_seginfo seginfo;
#endif
PVI oldvect;
int vecno = (irqno > 7) ? irqno + 0x68 : irqno + 0x8;
#ifdef __DJGPP__
_go32_dpmi_get_protected_mode_interrupt_vector(vecno, &seginfo);
oldvect = seginfo.pm_offset;
seginfo.pm_offset = handler;
seginfo.pm_selector = _go32_my_cs();
_go32_dpmi_allocate_iret_wrapper(&seginfo);
_go32_dpmi_set_protected_mode_interrupt_vector(vecno, &seginfo);
#else
oldvect = _dos_getvect(vecno);
_dos_setvect(vecno, handler);
#endif
return oldvect;
}
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