Category : C Source Code
Archive   : ADVGRAPH.ZIP
Filename : INSTISR.C

 
Output of file : INSTISR.C contained in archive : ADVGRAPH.ZIP


/* INSTISR.C installs the serial interrupt service
** routine. Refer to "serial interface at a glance"
** for register offsets used.
*/


#include
#include
#include


struct ISRVEC
{
unsigned vecl;
unsigned vech;
unsigned type;
};


extern struct ISRVEC isrvec;


instisr(service, request, port)
unsigned (*service)();
unsigned request;
unsigned long port;
{
unsigned far *base = (unsigned far *)port;
int i = 2;

outp((*base)+1, 1); /* select interrupts */

/* maskable hardware interrupts must be unmasked */
/* in the 8259 interrupt mask register */
outp(0x21, inp(0x21) & ~0x10); /* unmask COM1 interrupt */

/* set the interrupt vector using DOS */
setvect(request, service);

/* enable interrupts selected */
outp((*base)+4, inp((*base)+4) | 8);

/* clear pending interrupts */

inp(*base);
inp(*base);
inp(*base);

return(0);
}


setvect(vector, service)
int vector;
unsigned (*service)();
{
union REGS regs;
struct SREGS sregs;

regs.h.al = vector;
regs.h.ah = 0x35;
int86x(0x21, ®s, ®s, &sregs);
isrvec.vech = sregs.es; /* segment */
isrvec.vecl = regs.x.bx; /* offset */
isrvec.type = vector;

sregs.ds = FP_SEG(service); /* segment */
regs.x.dx = FP_OFF(service); /* offset */
regs.h.al = vector;
regs.h.ah = 0x25;
int86x(0x21, ®s, ®s, &sregs);
}


  3 Responses to “Category : C Source Code
Archive   : ADVGRAPH.ZIP
Filename : INSTISR.C

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