debugxv: SysReq detected; fixed: int21ah9 used DOS if InDos set

Author: Baron-von-Riedesel

HISTORY.TXT

@@ -268,3 +268,5 @@
          debugger visible there.
        - DEBUGX: restore hooked protected-mode interrupts when client
          terminates.
+       - DEBUGXV: break if SYSREQ is pressed.
+       - fixed: routine int21ah9 did use DOS, even if InDos flag was set.

MAKEX.BAT

@@ -16,5 +16,5 @@ jwasm -nologo -D?PM=1 -mz  -Fo build\DEBUGXG.EXE -Fl=build\DEBUGXG.LST -DCATCHIN
 echo creating debugxU - dx cmd uses unreal mode
 jwasm -nologo -D?PM=1 -bin -Fo build\DEBUGXU.COM -Fl=build\DEBUGXU.LST -DUSEUNREAL=1 -DCATCHINT0D=1 src\debug.asm
 
-echo creating debugxV - v cmd flips screens
-jwasm -nologo -D?PM=1 -bin -Fo build\DEBUGXV.COM -Fl=build\DEBUGXV.LST -DVXCHG=1 src\debug.asm
+echo creating debugxV - v cmd flips screens & sysreq trapped
+jwasm -nologo -D?PM=1 -bin -Fo build\DEBUGXV.COM -Fl=build\DEBUGXV.LST -DVXCHG=1 -DCATCHSYSREQ=1 src\debug.asm

README.TXT

@@ -172,7 +172,8 @@
    - DebugXV.COM: a version that takes care that screen output of
      debuggee and debugger are strictly separated - the new 'v'
      command is provided to watch the debuggee screen while the
-     debugger is active. This debug version is useful to debug
+     debugger is active. Additionally, the SysReq key is detected and
+     will activate the debugger. This debug version is useful to debug
      fullscreen text mode programs.
 
   d. The following features of MS Debug are not implemented:

src/DEBUG.ASM

@@ -99,6 +99,7 @@ MCB        equ 1	;support DM command
 EMSCMD     equ 1	;support Xx commands
 USESDA     equ 1	;use SDA to get/set PSP in real-mode
 STACKSIZ   equ 200h	;debug's stack size
+USEI1585   equ 0	;if CATCHSYSREQ==1, defines the method (ah=85h or ah=4Fh)
 
 ifndef CATCHINT01
 CATCHINT01 equ 1	;catch INT 01 (single-step)
@@ -127,6 +128,9 @@ endif
 ifndef CATCHINT0D
 CATCHINT0D equ 0	;catch exception 0Dh in real-mode
 endif
+ifndef CATCHSYSREQ
+CATCHSYSREQ equ 0	;catch int 15h (sysreq)
+endif
 ifndef CATCHINT31
 CATCHINT31 equ 0	;hook DPMI int 31h
 endif
@@ -497,7 +501,7 @@ else
 packet PACKET <0,0,0,0>
 endif
 
-intsave label dword
+intsave label dword	; must match order in inttab
 		dd 0	;saved vector i00
 if CATCHINT01
 		dd 0	;saved vector i01
@@ -516,9 +520,12 @@ oldi0C	dd 0	;saved vector i0C
 endif
 if CATCHINT0D
 oldi0D	dd 0	;saved vector i0D
+endif
+if CATCHSYSREQ
+oldi15	dd 0	;saved vector i15
 endif
 		dd 0	;saved vector i22
-if ?PM
+if ?PM ;must be last
 oldi2f	dd 0
 endif
 
@@ -579,7 +586,7 @@ INTITEM struct
 	dw ?
 INTITEM ends
 
-inttab label INTITEM
+inttab label INTITEM	; must match order in intsave
 	INTITEM <00h, intr00>
 if CATCHINT01
 	INTITEM <01h, intr01>
@@ -598,14 +605,14 @@ if CATCHINT0C
 endif
 if CATCHINT0D
 	INTITEM <0Dh, intr0D>
+endif
+if CATCHSYSREQ
+	INTITEM <15h, intr15>
 endif
 	INTITEM <22h, intr22>
 NUMINTS = ( $ - inttab ) / sizeof INTITEM
 if ?PM
 	db 2Fh
-NUMINTSX = NUMINTS+1
-else
-NUMINTSX = NUMINTS
 endif
 
 ;--- register names for 'r'. One item is 2 bytes.
@@ -802,6 +809,9 @@ endif
 if CATCHINT07 or CATCHEXC07
 exc07msg db 'Coprocessor not present',CR,LF,'$'
 endif
+if CATCHSYSREQ
+sysrqmsg db 'SysRq detected',CR,LF,'$'
+endif
 if EXCCSIP
 excloc	db 'CS:IP=',0
 endif
@@ -5260,30 +5270,30 @@ getpsp proc
 if ?PM
 	call ispm
 	jz getpsp_rm
-if NOEXTENDER
+ if NOEXTENDER
 	call doscallx
 	mov ax,2
 	int 31h
 	mov bx,ax
 	ret
-else
+ else
 	jmp doscall_rm
-endif
+ endif
 getpsp_rm:
 endif
 
 if USESDA
-if ?PM
+ if ?PM
 	cmp word ptr [pSDA+2],0
 	jz doscall_rm
-endif
+ endif
 	push ds
 	push si
-if ?PM
+ if ?PM
 	call LoadSDA
-else
+ else
 	lds si,[pSDA]
-endif
+ endif
 	mov bx,[si+10h]
 	pop si
 	pop ds
@@ -6710,27 +6720,26 @@ endif
 
 	mov di,offset intsave
 	mov si,offset inttab
-	mov cx,NUMINTSX
+if ?PM
+	mov cx,NUMINTS+1
+else
+	mov cx,NUMINTS
+endif
 nextint:
 	lodsb
-	mov bl,al
+	push ds
 	add si,2	; skip rest of INTITEM
-	xchg si,di
-	lodsw
-	mov dx,ax
-	lodsw
-	xchg si,di
-	cmp bl,22h
+	lds dx, [di]
+	add di,4
+	cmp al,22h
 	jz norestore
-	and ax,ax
+	mov bx, ds
+	and bx, bx
 	jz norestore
-	push ds
-	mov ds,ax
-	mov al,bl
 	mov ah,25h
 	int 21h
-	pop ds
 norestore:
+	pop ds
 	loop nextint
 
 ;--- Restore termination address.
@@ -7628,9 +7637,30 @@ io_error:
 	mov dx,offset openerr	;Error ____ opening file
 @@:
 int21ah9::
+if 1 ;v1.30: check InDos, if set use stdout()
+	call InDos
+	jnz use_stdout
+endif
 	mov ah,9
 	call doscall
 	ret
+if 1 ;v1.30: get size of $-string DS:DX, then call stdout; SI, CX not modified
+use_stdout:
+	push si
+	push cx
+	mov si, dx
+@@:
+	lodsb
+	cmp al, '$'
+	jnz @B
+	dec si
+	sub si, dx
+	mov cx, si
+	call stdout
+	pop cx
+	pop si
+	ret
+endif
 
 if EMSCMD
 
@@ -8071,8 +8101,9 @@ endif
 freemem endp
 
 ;--- this is called by "run"
-;--- better don't use INTs inside
-;--- set debuggee's INT 23/24
+;--- set debuggee's INT 23/24.
+;--- don't use INT 21h here, DOS might be "in use".
+;--- registers may be modified - will soon be set to debuggee's
 
 setint2324 proc
 	mov si,offset run2324
@@ -8091,7 +8122,10 @@ endif
 	movsw
 
 if ?PM
+	call InDos
+	jnz @F
 	call hook2f
+@@:
 endif
 
 	pop es
@@ -8282,6 +8316,38 @@ intr0D:
 	jmp intrtn
 endif
 
+if CATCHSYSREQ
+@@:
+	jmp cs:[oldi15]
+intr15:
+ if USEI1585
+	cmp ax, 8501h	;sysreq released?
+ else
+	cmp ax, 4F00h + (54h or 80h)	; use int 15h, ah=4Fh
+ endif
+	jnz @B
+	test cs:[bInDbg],1
+	jnz @B
+ ife USEI1585
+;--- if int 15h, ah=4Fh, no EOI has been sent to PIC yet
+;--- and the kbd may be disabled.
+	push ax
+	mov al, 20h
+	out 20h, al
+@@:
+	in al, 64h
+	test al, 2
+	jnz @B
+	mov al, 0AEh; enable kbd
+	out 64h, al
+	pop ax
+ endif
+ if ?PM
+	inc cs:[bNoHook2F]	; disable hooking
+ endif
+	mov cs:[run_int],offset sysrqmsg	;remember interrupt type
+	jmp intrtn
+endif
 ;--- Interrupt 3 (breakpoint interrupt) handler.
 
 intr03:
@@ -8351,18 +8417,18 @@ intrtn1::		;<--- entry for int 22
 if ?PM
 ;--- calling int 2Fh here is a problem, since breakpoints aren't reset yet.
 ;--- this makes it impossible to trace this interrupt.
-if DPMIMSW
+ if DPMIMSW
 	mov ax,1686h
 	int 2Fh
 	cmp ax,1
 	sbb ax,ax
-else
+ else
 	mov ax,cs
 	sub ax,[pspdbg]	;Z=rm,NZ=pm
 	cmp ax,1		;C=rm,NC=pm
 	cmc             ;NC=rm,C=pm
 	sbb ax,ax		;0=rm,-1=pm
-endif
+ endif
 	mov [regs.msw],ax	;0000=real-mode, FFFF=protected-mode
 endif
 
@@ -8449,10 +8515,9 @@ if VXCHG
 v_cmd proc
 	mov al,0
 	call swapscreen
- ifndef VXCHGBIOS
+ if 0;ndef VXCHGBIOS   ; v1.30: no longer needed, swapscreen has set cursor
 ;--- swapscreen has restored screen and cursor pos, but we want
 ;--- the cursor be shown on the screen - so set it thru BIOS calls.
-
 	mov ah, 0Fh        ; get current mode (and video page in BH)
 	int 10h
 	mov ah, 3          ; get cursor pos of page in BH
@@ -8493,9 +8558,15 @@ swapscreen proc
 	mov bl, es:[62h]
 	mov bh, 0
 	shl bx, 1
-	mov ax, es:[bx+50h]  ; get cursor pos of current page
-	xchg ax, [csrpos]
-	mov es:[bx+50h], ax
+	mov dx, es:[bx+50h]  ; get cursor pos of current page
+	xchg dx, [csrpos]
+if 0
+	mov es:[bx+50h], dx
+else
+	mov bh, es:[62h]
+	mov ah, 2
+	int 10h
+endif
 
 	push ds
 	pop es