bioskey

raw OCR

Keyboard interface, using BIOS services directly.

Defined in header <bios.h>

Syntax

#include <bios.h>
int bioskey(int cmd);

Portability

DOS	UNIX	Windows	ANSI C	C++ only
■

Remarks

bioskey performs various keyboard operations using BIOS interrupt 0x16. The parameter cmd determines the exact operation.

Return value

The value returned by bioskey depends on the task it performs, determined by the value of cmd:

0	If the lower 8 bits are nonzero, bioskey returns the ASCII charac- ter for the next keystroke waiting in the queue or the next key pressed at the keyboard. If the lower 8 bits are zero, the upper 8 bits are the extended keyboard codes defined in the IBM PC Technical Reference Manual.

1	This tests whether a keystroke is available to be read. A return value of zero means no key is available. The return value is 0xFFFFF (-1) if Ctrt-Brk has been pressed. Otherwise, the value of the next keystroke is returned. The keystroke itself is kept to be returned by the next call to bioskey that has a cmd value of zero.

2	Requests the current shift key status. The value is obtained by ORing the following values together:
Bit 7	0x80	Insert on
Bit 6	0x40	Caps on
Bits	0x20	Num Lock on
Bit 4	0x10	Scroll Lock on
Bits	0x08	Alt pressed
Bit 2	0x04	Ctrl pressed
Bitl	0x02	<r- Shift pressed
BitO	0x01	-^ Shift pressed

Example

#include <stdio.h>
#include <bios.h>
#include <ctype.h>

ttdefine RIGHT 0x01,
#define LEFT   0x02
#define CTRL   0x04
ttdefine ALT   0x08

int main(void)
{
   int key, modifiers;

   /* function 1 returns 0 until  a key is pressed */
   while (bioskey(l) == 0);

   /* function 0 returns the key  that is waiting */
   key = bioskey (0);

   /* use function 2 to determine  if shift keys are used */
   modifiers = bioskey (2);
   if (modifiers)  {
      printf(" [");
      if (modifiers & RIGHT) printf ("RIGHT");
      if (modifiers & LEFT)  printf ("LEFT");
      if (modifiers & CTRL)  printf ("CTRL");
      if (modifiers & ALT)   printf ("ALT");
      printf("]"),•
   }
   /* print out the character  read */
   if (isalnum(key & 0xFF))
      printf("'%c'\n" , key);
   else
      printf("%t02x\n", key);
   return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

Microsoft C runtime (search)

These are search links, not yet checked by hand.

Stable link: /3.1/bios.h/bioskey/ · short form /3.1/bioskey/