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Archive   : AMISL092.ZIP
Filename : RBKEYSWP.ASM

;**************************************************************************
;* *
;* RBkeyswap v3.01 9/24/95 *
;* (c) Copyright 1989, 1991, 1992, 1995 Ralf Brown *
;* *
;* Permission is granted to redistribute unmodified copies in their *
;* entirety. Modified copies may be distributed provided that they *
;* are clearly marked as modified and the original unmodified source *
;* code is distributed together with the modification. *
;* *
;* ------------------------------------------------------------------ *
;* *
;* RBkeyswap is a program to fix the IBM's enhanced keyboard, which *
;* places the Escape, Control, and CapsLock keys in the wrong places. *
;* After running RBkeyswap, Escape and `/~ will be exchanged, as will *
;* the left control key and the CapsLock key. The right control key *
;* will be unaffected. *
;* *
;* RBkeyswap loads itself high (no need for LOADHI or LH) into either *
;* an XMS upper memory block or a DOS 5.0 UMB. If neither is avail- *
;* able, RBkeyswap will go resident in low memory, using just 224 *
;* bytes (it needs a mere 160 bytes in high memory). Note that it will *
;* use 272 bytes under DOS 2.x, because those versions force all TSRs *
;* to leave at least that much resident. *
;* *
;* You need a BIOS which provides the keyboard intercept on INT 15h. *
;* If your BIOS does not support this, RBkeyswap will merely use up *
;* memory without doing anything. *
;* *
;* Usage: RBKEYSWP I install *
;* RBKEYSWP R remove from memory *
;* *
;* ------------------------------------------------------------------ *
;* *
;* Rebuilding RBkeyswap: *
;* TASM RBKEYSWP *
;* TLINK /T RBKEYSWP AMIS *
;* *
;**************************************************************************

INCLUDE AMIS.MAC

@Startup 2,00 ; need DOS 2.00
; this macro also takes care of declaring
; all the segments in the required order

;-----------------------------------------------------------------------
;
VERSION_NUM equ 0301h ; v3.01
VERSION_STR equ "3.01"

;-----------------------------------------------------------------------
;
; useful macros
;
LODSB_ES MACRO
DB 26h,0ACh ; LODSB ES:
ENDM

;-----------------------------------------------------------------------
; Put the resident code into its own segment so that all the offsets are
; proper for the new location after copying it into a UMB or down into
; the PSP.
;
TSRcode@

;-----------------------------------------------------------------------
; Declare the interrupt vectors hooked by the program, then set up the
; Alternate Multiplex Interrupt Spec handler
;
HOOKED_INTS 15h
ALTMPX 'Ralf B','RBkeyswp',VERSION_NUM

;-----------------------------------------------------------------------
; Now the meat of the resident portion, the keyboard intercept handler.
; We can save one byte by specifying the hardware reset handler set up by
; the ALTMPX macro above
;
ISP_HEADER 15h,hw_reset_2Dh
cmp ah,4Fh ; scan code translation?
jne not_ours ; if not, chain immediately
cmp al,0E1h ; is it a special key such as "Pause"?
je int15_setbranch
cmp al,0E0h ; or a right-{alt,ctrl}?
branch: ; (if prev scan was E0h or E1h, we will
; branch unconditionally)
je int15_setbranch ; the opcode here gets toggled between
; JE and JMP SHORT as needed
shl al,1 ; move break bit into CF
pushf ; and remember it for later
cmp al,1Dh*2 ; ctrl?
je ctrl_or_capslock
cmp al,3Ah*2 ; capslock?
je ctrl_or_capslock
cmp al,01h*2 ; ESC?
je esc_or_tilde
cmp al,29h*2 ; backquote/tilde key?
jne int15_no_xlat
esc_or_tilde:
xor al,0Fh*2 ; (AL xor 0F) xor 27 == (AL xor 28h)
; 01h -> 29h, 29h -> 01h
; thus esc and tilde swapped
ctrl_or_capslock:
xor al,27h*2 ; 1Dh -> 3Ah, 3Ah -> 1Dh
; thus left-ctrl and capslock swapped
int15_no_xlat:
popf ; retrieve break bit in CF
rcr al,1 ; and add to translated scan code
jmp short int15_done

int15_setbranch:
xor byte ptr cs:branch,(74h xor 0EBh) ; toggle between JE and JMP
int15_done:
stc ; use the scan code
not_ours:
jmp ORIG_INT15h

TSRcodeEnd@

;-----------------------------------------------------------------------

_TEXT SEGMENT 'CODE'
ASSUME cs:_TEXT,ds:NOTHING,es:NOTHING,ss:NOTHING

banner db 'RBkeyswap v',VERSION_STR,' (c) Copyright 1989,1991,1992 Ralf Brown',13,10
db "$"
usage db 9,'Swaps Esc/tilde and CapsLock/LeftCtrl',13,10
db 'Usage:',9,'RBKEYSWP I',9,'install in memory',13,10
db 9,'RBKEYSWP R',9,'remove from memory',13,10
db '$'
installed_msg db "Installed.",13,10,"$"
already_inst_msg db "Already installed.",13,10,"$"
cant_remove_msg db "Can't remove from memory.",13,10,"$"
uninstalled_msg db "Removed.",13,10,"$"

@Startup2 Y
push ds
pop es
ASSUME ES:_INIT
push cs
pop ds
ASSUME DS:_TEXT
;
; say hello
;
DISPLAY_STRING banner
mov bx,1000h ; set memory block to 64K
mov ah,4Ah
int 21h
mov si,81h ; SI -> command line
cld ; ensure proper direction for string ops
cmdline_loop:
lodsb_es
cmp al,' ' ; skip blanks and tabs on commandline
je cmdline_loop
cmp al,9
je cmdline_loop
and al,0DFh ; force to uppercase
cmp al,'I'
je installing
cmp al,'R'
je removing
jmp show_usage
installing:
;
; place any necessary pre-initialization here
;
INSTALL_TSR ,BEST,TOPMEM,inst_notify,already_installed

removing:
UNINSTALL cant_uninstall
push cs
pop ds
DISPLAY_STRING uninstalled_msg
mov ax,4C00h
int 21h

show_usage:
mov dx,offset _TEXT:usage
jmp short exit_with_error
cant_uninstall:
mov dx,offset _TEXT:cant_remove_msg
jmp short exit_with_error
already_installed:
mov dx,offset _TEXT:already_inst_msg
exit_with_error:
mov ah,9
int 21h
mov ax,4C01h
int 21h

inst_notify:
DISPLAY_STRING installed_msg
ret

_TEXT ENDS

end INIT