Date:	Mon, 8 Dec 1997 16:56:58 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To:	djgpp-workers AT delorie DOT com
cc:	DJ Delorie <dj AT delorie DOT com>, Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Subject:	Enhanced signal support (1/2)
Message-ID:	<Pine.SUN.3.91.971208165446.4200q-100000@is>
MIME-Version:	1.0

These changes add support for signal SIGQUIT.  By default it is
generated when Ctrl-\ is pressed and aborts the program with a
traceback, like Ctrl-BREAK does.

These changes also make the keys which generate SIGINT and SIGQUIT
user-definable instead of being hard-coded.  The intent is to provide
the basis for termio-like ioctl functionality and termios
enhancements.  Right now, the only program I know that needs to change
the SIGINT key is Emacs.

This message includes changes to exceptn.S only; the rest is sent in a
separate message.  Since my assembly experience is virtually
nonexistent, please examine this carefully in case I did something
dangerous or inefficient.  Please also review the questions related to
design of these features that I send in yet another message.

*** src/libc/go32/exceptn.S~0	Sun Dec 10 20:36:18 1995
--- src/libc/go32/exceptn.S	Sat Dec  6 14:44:46 1997
*************** ___djgpp_app_DS:		.word	0
*** 257,262 ****
--- 257,270 ----
  ___djgpp_dos_sel:		.word	0
  	.global	___djgpp_hwint_flags
  ___djgpp_hwint_flags:		.word	0
+ 	.global ___djgpp_sigint_key
+ ___djgpp_sigint_key:		.word	0	/* scan code and kb status */
+ 	.global ___djgpp_sigint_mask
+ ___djgpp_sigint_mask:		.word	0	/* kb status mask */
+ 	.global ___djgpp_sigquit_key
+ ___djgpp_sigquit_key:		.word	0
+ 	.global ___djgpp_sigquit_mask
+ ___djgpp_sigquit_mask:		.word	0
  	.global	___djgpp_old_kbd
  ___djgpp_old_kbd:		.long	0,0
  	.global	___djgpp_old_timer
*************** hw_to_excp:
*** 287,315 ****
  	.global	___djgpp_kbd_hdlr
  ___djgpp_kbd_hdlr:
  	pushl	%eax
  	pushl	%ds
     	.byte	0x2e				/* CS: */
  	testb	$1, ___djgpp_hwint_flags	/* Disable? */
  	jne	Lkbd_chain
- /* Check CTRL state */
  	movw	%cs:___djgpp_dos_sel, %ds	/* Conventional mem selector */
  /*	movw	$0x7021,0xb0f00		*/	/* Test code - write to mono */
! 	testb	$4,0x417			/* Test KB flags: CTRL down? */
! 	je	Lkbd_chain
! 	testb	$8,0x417			/* Test KB flags: ALT down? */
! 	jne	Lkbd_chain			/* Don't capture ALT-CTRL-C */
! /* Check port for scan code */
! 	inb	$0x60,%al
! 	cmpb	$0x2e,%al
  	jne	Lkbd_chain
  /* Clear interrupt, (later: remove byte from controller?)
  	movb	$0x20,%al
  	outb	%al,$0x020	*/
  98:
! 	movb	$0x79,%al
  	call	___djgpp_hw_exception
  Lkbd_chain:
  	popl	%ds
  	popl	%eax
  	ljmp	%cs:___djgpp_old_kbd
  
--- 295,335 ----
  	.global	___djgpp_kbd_hdlr
  ___djgpp_kbd_hdlr:
  	pushl	%eax
+ 	pushl	%ebx
  	pushl	%ds
     	.byte	0x2e				/* CS: */
  	testb	$1, ___djgpp_hwint_flags	/* Disable? */
  	jne	Lkbd_chain
  	movw	%cs:___djgpp_dos_sel, %ds	/* Conventional mem selector */
  /*	movw	$0x7021,0xb0f00		*/	/* Test code - write to mono */
! /* Check Keyboard status bits */
! 	movb	0x417,%ah			/* Get KB status byte */
! 	testb	$1,%ah
! 	je	6f
! 	orb	$2,%ah	/* If RShift is set, set LShift as well */
! 6:
! 	inb	$0x60,%al			/* Read the scan code */
! 	movb	%ah,%bh				/* Save KB status */
! 	andb	%cs:___djgpp_sigint_mask, %ah	/* Mask off irrelevant bits */
! 	cmpw	%cs:___djgpp_sigint_key, %ax	/* Test for SIGINT */
! 	jne	7f
! 	movb	$0x79,%bh			/* SIGINT */
! 	jmp	98f
! 7:
! 	movb	%bh,%ah				/* Restore KB status */
! 	andb	%cs:___djgpp_sigquit_mask, %ah	/* Mask off irrelevant bits */
! 	cmpw	%cs:___djgpp_sigquit_key, %ax	/* Test for SIGQUIT*/
  	jne	Lkbd_chain
+ 	movb	$0x7a,%bh			/* SIGQUIT */
  /* Clear interrupt, (later: remove byte from controller?)
  	movb	$0x20,%al
  	outb	%al,$0x020	*/
  98:
! 	movb	%bh,%al
  	call	___djgpp_hw_exception
  Lkbd_chain:
  	popl	%ds
+ 	popl	%ebx
  	popl	%eax
  	ljmp	%cs:___djgpp_old_kbd
  

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