c语言中时间陷阱的实现

#include<dos.h>

#define Sizeprogram 375

void interrupt (*oldtimer)();

void interrupt newtimer();

static struct SREGS seg;

unsigned intsp,intss;

unsigned myss,stack;

unsigned vseg;

int running=0;

int m1,m2,m3=0;

int (*sub_ptr)();

void on_timer();

void timer_on();

void timer_off();

void on_timer(t,pp);

int t;

int (*pp)();

{

sub_ptr=pp;

m1=t;

segread(&seg);

stack=(Sizeprogram-(seg.ds-seg.cs))*16-300;

myss=_SS;

oldtimer=getvect(0x1c);

}

void timer_on()

{

m2=0;

m3=1;

setvect(0x1c,newtimer);

}

void timer_off()

{

m3=0;

setvect(0x1c,oldtimer);

}

void interrupt newtimer()

{

(*oldtimer)();

if(running==0)

running=1;

disable();

intsp=_SP;

intss=_SS;

_SP=stack;

_SS=myss;

enable();

if(m3==1){

if(m2==m1*18){

m2=0;

(*sb_ptr)();

}

m2+=1;

}

disable();

_SP=intsp;

_SS=intss;

enable();

running=0;

}

}

#include<dos.h>

#define TRUE 1

void ptr();

main()

{

char ch;

char *p:

p=(char *)ptr;

on_timer(t,p);

while(TRUE){

ch=getch();

switch(ch){

case ''0'': timer_off();break;

case ''1'': timer_on();break;

case ''2'': timer_off();brea;

default: printf("%c",ch);

}

}

}

void ptr()

{

union REGS in,out;

in.h.al=''A'';

in.h.ah=14;

int86(0x10,&in,&out);

}