Date:	Mon, 12 Jan 1998 18:21:46 -0500 (EST)
Message-Id:	<199801122321.SAA13895@delorie.com>
From:	DJ Delorie <dj AT delorie DOT com>
To:	djgpp-workers AT delorie DOT com
Subject:	[MCLSSAA2 AT fs2 DOT mt DOT umist DOT ac DOT uk: Hooking interrupt 9 : a DIFF]

------- Start of forwarded message -------
From: "Anthony.Appleyard" <MCLSSAA2 AT fs2 DOT mt DOT umist DOT ac DOT uk>
Organization:  Materials Science Centre
To: dj AT delorie DOT com
Date:          Mon, 12 Jan 1998 16:43:04 GMT
Subject:       Hooking interrupt 9 : a DIFF
Reply-to: Anthony DOT Appleyard AT umist DOT ac DOT uk
Priority: normal
X-mailer: Pegasus Mail v3.31

  Herewith suggested alterations to make it easier for a user to hook
interrupt 9 to get the keyboard events raw:-
  My version of djgpp v2 is dated thus:-
    directory D:\DJGPPV2\SRC\LIBC\GO32, has 25 entries, 112450 bytes
    EXCEPTN.S         10598 1995 Dec 10 15.36.18
    GO32CBRK.C          652 1995 May  7 21.21.42

  Suggested alterations to DJGPP\SRC\LIBC\GO32\GO32CBRK.C :-
  ==================================================================
*** go32cbrk.old	Mon Jan 12 15:48:04 1998
- --- go32cbrk.c	Mon Jan 12 15:49:10 1998
***************
*** 2,7 ****
- --- 2,9 ----
  #include <sys/exceptn.h>
  #include <go32.h>
  
+ extern void (*userskeyboardhandler)(int X);
+ 
  void _go32_want_ctrl_break(int yes)	/* Yes means counting */
  {
    int ctrl_break_counting = __djgpp_hwint_flags & 2;
  ==================================================================

  Suggested alterations to DJGPP\SRC\LIBC\GO32\EXCEPTN.S:-
  ==================================================================
*** _ex.old	Mon Jan 12 14:54:06 1998
- --- _ex.s	Mon Jan 12 16:33:10 1998
***************
*** 284,293 ****
- --- 284,324 ----
  	iret
  
  	.align 4
+ 	.global	_userskeyboardhandler
+ _userskeyboardhandler:	.int 0	/* void (*userskeyboardhandler)(int X); */
+ /* If not 0, the interrupt 9 hook routine will call this function with:- */
+ /*  X     &255 == keyboard event */
+ /* (X>> 8)&255 == keyboard shift status as if from (AH=2, int 16h) */
+ /* (X>>16)&255 == keyboard extended shift status as if from (AH=12h, int 16h) */
+ _calluserskeyboardhandler:
+ 	pushl %ebx			/* save EBX */
+ 	movl _userskeyboardhandler,%ebx
+ 	testl %ebx,%ebx			/* if zero, there is no function */
+ 	je NOUSERHDLR
+ 	pushl %eax
+ 	pushw %fs
+ 	pushf
+ 	sti				/* disable interrupts */
+ 	movw   __go32_info_block+26,%ax
+ 	movw   %ax,%fs			/* FS = _dos_ds */
+ 	.byte  0x64			/* use segment reg FS */
+ 	movw   0417,%ax			/* [0x417] [0x418] are shift status */
+ 	sall   $8,%eax			/* move EAX one byte up */
+ 	inb    $0x60,%al		/* read keyboard event into AL */
+ 	pushl  %eax			/* parameter for call */
+ 	call   *%ebx			/* call the function */
+ 	popf
+ 	popw   %fs
+ 	popl   %eax
+ NOUSERHDLR:
+ 	popl   %ebx
+ 	ret
+ 
  	.global	___djgpp_kbd_hdlr
  ___djgpp_kbd_hdlr:
  	pushl	%eax
  	pushl	%ds
+ 	call	_calluserskeyboardhandler
     	.byte	0x2e				/* CS: */
  	testb	$1, ___djgpp_hwint_flags	/* Disable? */
  	jne	Lkbd_chain
***************
*** 318,323 ****
- --- 349,355 ----
  ___djgpp_kbd_hdlr_pc98:
  	pushl	%eax
  	pushl	%ds
+ 	call	_calluserskeyboardhandler
     	.byte	0x2e				/* CS: */
  	testb	$1, ___djgpp_hwint_flags	/* Disable? */
  	jne	Lkbd_chain
------- End of forwarded message -------

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