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/* keywatch.c 12-29-91 Robert Mashlan, Public Domain *\
DOS compiler portability modifications added by Bob Stout,
1:106/2000.6
This program monitors the keyboard interrupt, and stores the
status of each key as to whether it is pressed or released.
This is done by capturing interrupt 9, and watching the make/break
codes. The status is updated in the keys array, where 1 means
that the key is pressed, while 0 means the key is released. The
key array is uses the scan code for an index instead of the ascii
character. It is simple enough to find the scan code for a key,
just run this program and watch the display.
The ekeys array will reflect the status of keys found on an AT
keyboard. For instance, the left and right alt keys are
differentiated, as well as the edit control keys on the numeric
keypad and the one not on the numeric keypad.
Since this program installs an interrupt handler, it should be
terminated normally, such the keyboard handler can be removed.
The ^C/^Break exit is captured via signal(), but all possible
exits should be trapped.
\* */
#include <stdio.h>
#include <dos.h>
#include <conio.h>
#include <signal.h>
#define BYTE unsigned char
#if defined(__TURBOC__)
#define _interrupt interrupt
#define _far far
#define IN_PORT(port) inportb(port)
#define IN_PORTW(port) inport(port)
#define OUT_PORT(port, val) outportb(port, val)
#define OUT_PORTW(port, val) outport(port, val)
#else
#if defined(__ZTC__)
#include <int.h>
#else /* MSC, QC, Watcom */
#define getvect(n) _dos_getvect(n)
#define setvect(n,v) _dos_setvect(n,v)
#endif
#define IN_PORT(port) inp(port)
#define IN_PORTW(port) inpw(port)
#define OUT_PORT(port, val) outp(port, val)
#define OUT_PORTW(port, val) outpw(port, val)
#endif
volatile char keys[128]; /* array of key states */
volatile char ekeys[128]; /* array of AT key states */
#define KEYPORT 0x60 /* keyboard scan code port */
#define keyport() IN_PORT(KEYPORT)
/* macro that returns the scancode of the key that caused */
/* the interrupt */
/* Define: *\
installisr()
installation macro, installs newkbisr() in the keyboard
interrupt chain
removeisr()
removal macro, call to remove newkbisr() from interrupt
chain. oldkbisr() must be removed before program ends
\* */
#ifdef __ZTC__
#define installisr() int_intercept(0x09, newkbisr, 0)
#define removeisr() int_restore(0x09);
#else
#define installisr() (oldkbisr=getvect(0x09),setvect(0x09,newkbisr))
#define removeisr() setvect(0x09,oldkbisr)
#ifdef __TURBOC__
void _interrupt (_far *oldkbisr)(void); /* address of old ISR */
#else
void (_interrupt _far *oldkbisr)(void); /* address of old ISR */
#endif
#endif
#ifdef __ZTC__
int newkbisr(struct INT_DATA *pd)
#elif defined(__TURBOC__)
void _interrupt newkbisr(void)
#else
void _interrupt _far newkbisr(void)
#endif
{
static extkey;
BYTE scancode = (BYTE)keyport(); /* read keyboard scan code */
if (scancode == 0xe0)
extkey = 1; /* use ekey array on next scan code */
else
{
if (scancode & 0x80) /* key released */
(extkey ? ekeys : keys)[scancode & 0x7f] = 0;
else (extkey ? ekeys : keys)[scancode] = 1;
extkey = 0;
}
#ifdef __ZTC__
return 0; /* chain to previous keyboard ISR */
#else
oldkbisr(); /* chain to previous keyboard ISR */
#endif
}
int keyspressed(void) /* returns number of keys being held down */
{
int i, result = 0;
for (i = 0; i < 128; i++)
{
result += keys[i];
result += ekeys[i];
}
return result;
}
int main(void)
{
int lastkeycount = 0;
signal(SIGINT,SIG_IGN); /* ingnore ^C and ^Break */
installisr(); /* install interrupt handler */
while(1)
{
int i;
if (keyspressed() != lastkeycount) /* change in keystatus */
{
lastkeycount = keyspressed();
puts("---");
for(i = 0; i < 128; i++)
{
if (keys[i])
printf("key with scan code %02x "
"has been pressed\n", i);
if (ekeys[i])
printf("key with scan codes e0 %02x "
"had been pressed\n", i);
}
}
if (kbhit() && getch()==0x1b) /* terminate when Esc pressed */
break;
}
removeisr(); /* remove interrupt handler */
return 0;
}
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