                page    66,132

; This file was modified by Ben Diss (CIS 71270,341) to fix the ALT key
; bug and to provide the following inmprovements:
;
; 1. The hot key to increase or decrease intensity is CTRL-ALT plus the
;    arrow key.
; 2. The replaced ISRs are now called at the beginning of all ISRs
;    rather than JMPed to at the end.  This eliminates some problems with a
;    few clone systems.
; 3. Hot-key blanking has been added via SHIFT-SHIFT.
; 4. Hot-key disabling has been added via CTRL-ALT-D and re-enabling via
;    CTRL-ALT-E.
; 5. Mouse support has been added, so that any use of the mouse will
;    reset the time-out blanker.
; 6. The version number has been changed to 1.01 to relect the changes.
;
; Although I have used this program on my system since it was published,
; I cannot promise that it will work on yours, as I have not done any
; in-depth testing.  This program is provided "as-is" without any
; warrenty of any kind.  The original version was written for PC
; Magazine and is Copyright 1989, Ziff Communications Co.  I hereby
; release all claims to rights for the modifications I have made.
;
;      --- Ben
;
;-------------------------------------------------------------------------
; On 1-17-90, version 1.02:
;
; I rewrote the mouse routines so that all mouse drivers will be
;supported on all types of systems.  The old method only worked for
;serial mouses.  Also, when no mouse driver was loaded with certain
;programs that did use a mouse, the system would go into orbit.
;
; The method used now, polls the mouse driver twice a second for any
;change in the status.  I did it this way to reduce the overhead of the
;polling routine.  The side effect is that it is almost impossible to
;detect the press of a button using this method.
;
;----------------------------------------------------------------------------
; On 1-18-90, version 1.02:
;
;  Commented out the interval timer for the mouse polling routine.  I
;found no difference with and without the delay using a number of
;benchmark programs.  To retore them, simply delete the comments in from
;of those lines.
;
;----------------------------------------------------------------------------
; On 1-20-90, version 1.03:
;
;  WHOOPS!  I forgot to bypass the INT 33 monitoring routine when there
;is no mouse driver installed.
;
;============================================================================
; DIMMER.COM allows VGA users to interactively brighten or dim the screen.
; Syntax is:
;
;       DIMMER [/U] [/V[+|-]] [/D mmm [+|-]xx] [[+|-]xx]
;
; where /U = Uninstall the program
;       /D = Adjust intensity by xx after mmm minutes of inactivity
;       xx = Numeric code from -63 to +63 representing relative
;            amount by which to adjust the intensity
;       /V = Reset delay timer on call to BIOS video interrupt. The
;	     default is V-.
;
; COMMAND LINE INTENSITY CONTROL
;
;       DIMMER /D 1 -63 causes the screen to blank after 1 minute of
;       inactivity.  DIMMER /D 0 cancels any time delay previously entered.
;       DIMMER -20 causes the screen to immediately dim 20 intensity levels.
;       DIMMER 0 restores the screen intensity to what it was when DIMMER
;       was installed.  In all cases, DIMMER becomes RAM-resident so that
;       intensity levels can also be adjusted interactively.
;       DIMMER /D 1 -63 /V causes the screen to blank after 1 minute of
;   	inactivity.  If a program calls any BIOS video routines, the
;       screen is reset to its original brightness.
;
; INTERACTIVE INTENSITY CONTROL
;
;       With DIMMER installed, Ctrl-Alt-UpArrow increases the display intensity
;       by 1 level, Ctrl-Alt-DnArrow decreases the intensity by 1 level, and
;       Ctrl-Alt-Home restores the screen intensity to what it was when DIMMER
;       was installed.
;============================================================================
 
                code    segment
                assume  cs:code
 
                org     2Ch
env_segment     dw      ?                       ;Address of environment block
                org     80h
command_tail    dw      ?                       ;Address of command tail
 
                org     100h
main:           jmp     initialize              ;Go to initialization code
 
program         db      "Dimmer 1.03 "
copyright       db      "(c) 1989 Ziff Communications Co.",13,10
authors         db      "PC Magazine ",254," Doug Boling and Jeff Prosise"
                db      "$",1Ah
 
dimmer_val	db      0                       ;Relative dimmer value
delaydimval	db      0                       ;Delayed dimmer value
wait_time	dw      -1                      ;Delay until screen blank
dim_counter	dw      -1                      ;Number of minutes to delay
second_cnt	dw      1092                    ;Timer ticks per minute
restorebyvid	db	0			;1 = delay reset by video call
vid_function	dw      0                       ;Saved video function
int08h          dd      ?                       ;Int 8 vector (Timer)
int09h          dd      ?                       ;Int 9 vector (Keyboard)
int10h          dd      ?                       ;Int 10 vector (Video)
INT33H          dd      ?                       ;Int 33 vector (Mouse)
MOUSE_INST      db      ?                       ;0 if no mouse , -1 if present
MOUSE_BUZY      DB      0                       ;0=not buzy, -1=buzy
 
;============================================================================
; RESET_DELAY reset the delay counter
;============================================================================

RSHIFT  =       000000001B      ; Right Shift Key is Depressed
LSHIFT	=	000000010B	; Left Shift Key is Depressed
CTRL	=	000000100B	; Ctrl Key is Depressed
ALT	=	000001000B	; Alt Key is Depressed

KEYS_UP DB      1               ;0=keys not up since blank
SAVE_WAIT	DW	?	;saves the wait_time

reset_delay	proc	near 

        CMP     CS:[KEYS_UP],1          ;keys released since last
        JNE     done_reset              ;  forced blank?
	mov     cs:[second_cnt],1092	;Reset delay counters
	mov     ax,cs:[wait_time]
	xchg    cs:[dim_counter],ax
        or      ax,ax                   ;If counter was 0, reset the
        jne     done_reset              ;  screen intensity
	mov     ah,cs:[dimmer_val]
	call    adj_palette_2
done_reset:
	ret

reset_delay	endp

;============================================================================
; MOUSEINT monitors the mouse driver for activity
;============================================================================

        EVEN                            ; word align to assist prefetch que

MOUSEINT        PROC    NEAR

        MOV     MOUSE_BUZY,-1           ; mouse driver is now buzy
        PUSHF                           ; push flags
        CALL    INT33H                  ; call the driver
        MOV     MOUSE_BUZY,0            ; mouse is now free
        IRET                            ; return

MOUSEINT        ENDP

;============================================================================
; CHECK_MOUSE polls the mouse driver to check for movement
;============================================================================

MOUSE_BX        DW      ?
MOUSE_CX        DW      ?
MOUSE_DX        DW      ?

        EVEN                            ; word align to assist prefetch que

CHECK_MOUSE     PROC    NEAR

        PUSH    BX                      ; save registers
        PUSH    CX
        PUSH    DX

        MOV     AX,3                    ; Get mouse position and status
        PUSHF                           ; push the flags and
        CALL    INT33H                  ;   call the mouse driver

        CMP     BX,MOUSE_BX             ; if button status has changed
        JNE     MOUSE_MOVED             ;   then reset the delay
        CMP     CX,MOUSE_CX             ; if the horiz position has changed
        JNE     MOUSE_MOVED             ;   then reset the delay
        CMP     DX,MOUSE_DX             ; if the vert position has changed
        JNE     MOUSE_MOVED             ;   then reset the delay
        JMP     SHORT SAVE_MOUSE        ; else just save the status

MOUSE_MOVED:
        CALL    RESET_DELAY             ; reset the delay counter and restore
                                        ;  the screen if necessary
SAVE_MOUSE:
        MOV     MOUSE_BX,BX             ; save the mouse driver status
        MOV     MOUSE_CX,CX
        MOV     MOUSE_DX,DX

        POP     DX                      ; restore the registers
        POP     CX
        POP     BX
        RET

CHECK_MOUSE     ENDP


;============================================================================
; TIMERINT services the BIOS timer interrupt.
;============================================================================

;COUNTER DB      9                       ; mouse polling interval counter

        EVEN                            ; word align to assist prefetch que

timerint        proc    far
        pushf                           ;Push flags
        call    int08h                  ;Call BIOS timer routine
        sti                             ;Enable interrupts

        push    ax                      ;Save AX

        CMP     MOUSE_INST,-1           ; if mouse not installed
        JNE     TIMER_1                 ;   then skip mouse check
;
; Check the mouse driver only once per second.  This saves CPU time, but
; also makes detecting a button press very unlikely.
;
;        DEC     COUNTER                 ; decrement the interval timer
;        JNZ     TIMER_1                 ; if not zero, then skip mouse check
;        MOV     COUNTER,9               ; reset the interval timer

        CMP     MOUSE_BUZY,-1           ; if the mouse driver is buzy
        JE      TIMER_1                 ;   then skip the mouse check

        CALL    CHECK_MOUSE             ;   else check for mouse movement

TIMER_1:
        mov     ax,cs:[dim_counter]     ;Get delay counter
        cmp     ax,0FFFFh               ;See if timer enabled
        je      timer_exit              ;Exit if not enabled
        or      ax,ax                   ;Exit if timer at 0 to
        je      timer_exit              ;  prevent rollover.
 
        dec     cs:[second_cnt]         ;Decrement seconds and exit
        jnz     timer_exit              ;  if not zero
	mov     word ptr cs:[second_cnt],1092
        dec     ax                      ;Decrement minute counter
	mov     cs:[dim_counter],ax	;Update delay counter
        or      ax,ax                   ;Exit if timer hasn't
        jne     timer_exit              ;  reached zero

	mov     ah,cs:[delaydimval]	;Get dimmer value
        call    adj_palette_2           ;Modify color registers
timer_exit:
	pop	ax	;Restore AX and exit
	iret
timerint	endp

;============================================================================
; KBINT services the keyboard interrupt.
;============================================================================

        EVEN                            ; word align to assist prefetch que

kbint   proc    far

	PUSHF
        CALL    INT09H                  ;BIOS keyboard handler
        sti                             ;Enable interrupts
        push    ax                      ;Save AX

        call    reset_delay             ; reset the delay counter

        MOV     AH,2                    ;Get keyboard shift status
	INT	16H

        and     al,0Fh                  ;Mask upper 4 bits
        cmp     al,ALT+CTRL             ;Check for Alt key
        je      alt_found               ;Continue if Alt is pressed

	CMP	AL,LSHIFT+RSHIFT	;Check for our hot-key
	JNE	kbint0a

	MOV     AH,CS:[DELAYDIMVAL]	;else get dimmer value
        CALL    ADJ_PALETTE_2           ;Modify color registers
	MOV	CS:[DIM_COUNTER],0	;Set counter dimmed screen
        MOV     CS:[KEYS_UP],0          ;Set key_up to 'not yet'
	JMP	SHORT kbint_done
kbint0a:
	CMP	AL,0
	JNE	KBINT_DONE
	MOV	CS:[KEYS_UP],1
kbint_done:
	POP	AX
	IRET

alt_found:
	in	al,60h

        CMP     AL,20H                  ;Check for 'D' to disable
	JNE	kbint0b
	MOV	AX,CS:[WAIT_TIME]
	MOV	CS:[SAVE_WAIT],AX	;Save the wait_time
	MOV	CS:[DIM_COUNTER],0FFFFH	;Disable dim_counter
	MOV	CS:[WAIT_TIME],0FFFFH	;DIsable wait_time
	MOV	AX,0E07H
	INT	10H
	JMP	SHORT kbint4

kbint0b:
        CMP     AL,12H                  ;Check for 'E' to enable
	JNE	kbint0c
	MOV	AX,CS:[SAVE_WAIT]
	MOV	CS:[WAIT_TIME],AX
	MOV	CS:[DIM_COUNTER],AX
	MOV	CS:[SECOND_CNT],1092	;Reset delay counters
	MOV	AX,0E07H
	INT	10H
	MOV	AX,0E07H
	INT	10H
	JMP	SHORT kbint4
kbint0c:
        cmp     al,72                   ;Check for UpArrow
	jne     kbint1
	cmp     cs:[dimmer_val],63	;Increment color registers
        jge     kbint3                  ;  by 1 if dimmer value
        inc     cs:[dimmer_val]         ;  isn't maxed out
	jmp     short kbint3
kbint1:
        cmp     al,80                   ;Check for DnArrow
	jne     kbint2
	cmp     cs:[dimmer_val],-63	;Decrement color registers
        jle     kbint3                  ;  by 1 if dimmer value
        dec     cs:[dimmer_val]         ;  isn't zeroed out
	jmp     short kbint3
kbint2:
        cmp     al,71                   ;Reset color registers if
        jne     kbint_done              ;  Alt-Home was pressed
	mov     cs:[dimmer_val],0
kbint3:
	mov     ah,cs:[dimmer_val]	;Get dimmer value
        call    adj_palette_2           ;Modify color registers

kbint4:
	MOV	AH,1
	INT	16H
	JZ	KBINT_EXIT

	MOV	AH,0
	INT	16H
	JMP	SHORT kbint4

KBINT_EXIT:
	pop	ax	;Restore AX and exit
	iret

kbint	endp
 

;============================================================================
; VIDEOINT services the BIOS video interrupt.
;============================================================================

        EVEN                            ; word align to assist prefetch que

videoint        proc    far
        mov     cs:[vid_function],ax    ;Save function number
        pushf                           ;Push flags
        call    int10h                  ;Call video BIOS routine
        sti                             ;Enable interrupts
        push    ax                      ;Save AX
 
	cmp	cs:[restorebyvid],0	;If video checking enabled,
        je      video_1                 ;  check delay counter.
        cmp     word ptr cs:[dim_counter],0
        jne     video_1                 ;Restore color register
        mov     ah,cs:[dimmer_val]      ;  values if timed delay
        call    adj_palette_2           ;  has dimmed the screen
        mov     cs:[second_cnt],1092    ;Reset delay counters
        mov     ax,cs:[wait_time]
        mov     cs:[dim_counter],ax
 
video_1:
        mov     ax,cs:[vid_function]    ;See what function was called
        or      ah,ah                   ;Check for mode change
        je      refresh_palette
        cmp     ah,11h                  ;Check for mode reset
        je      refresh_palette
 
        cmp     ax,1010h                ;Check for changes to the
        je      refresh_buffer          ;  VGA color registers
        cmp     ax,1012h                ;  made thru the video
        je      refresh_buffer          ;  BIOS
        cmp     ax,101Bh
        jne     video_exit
refresh_buffer:
        call    get_palette             ;Reload register array
        jmp     short video_exit
 
refresh_palette:
        mov     ah,cs:[dimmer_val]      ;Get dimmer adjust value
        call    adj_palette_2           ;Modify palette
video_exit:
        pop     ax                      ;Restore AX and exit
        iret
videoint        endp
 
;----------------------------------------------------------------------------
; ADJ_PALETTE_1 adjusts the VGA color registers to their original values
; plus the current dimmer value.
;   Entry:  AH - Dimmer value
;           DS - Segment where color register values are stored
;----------------------------------------------------------------------------
adj_palette_1   proc    near
                cld                             ;Clear direction flag
                push    cx                      ;Save registers
                push    dx
                push    si
 
                mov     si,offset end_res       ;Point SI to buffer
                                                ;  containing original values
                mov     dx,03C8h                ;Write address register
                xor     al,al                   ;Set beginning address
                cli                             ;Disable interrupts
                out     dx,al
                mov     cx,256 * 3              ;256 color registers
                mov     dx,03C9h                ;Write data register
adj_loop1:
                lodsb                           ;Get color value
                call    mod64_add               ;Add dimmer value
                out     dx,al                   ;Write data to color register
                loop    adj_loop1               ;Loop until done
 
                sti                             ;Enable interrupts
                pop     si                      ;Restore registers and exit
                pop     dx
                pop     cx
                ret
adj_palette_1   endp
 
;----------------------------------------------------------------------------
; ADJ_PALETTE_2 adjusts the VGA color registers to their original values
; plus the current dimmer value.
;   Entry:  AH - Dimmer value
;----------------------------------------------------------------------------
adj_palette_2   proc    near
                push    ds                      ;Save DS
                push    cs                      ;Point DS to code segment
                pop     ds
                call    adj_palette_1           ;Modify color registers
                pop     ds                      ;Restore DS and exit
                ret
adj_palette_2   endp
 
;----------------------------------------------------------------------------
; MOD64_ADD adds AH to AL using modulo 64 math.
;----------------------------------------------------------------------------
mod64_add       proc    near
                or      al,al                   ;If 0, don't brighten
                je      mod2
                add     al,ah
                cmp     al,0                    ;See if underflow
                jg      mod1
                mov     al,0                    ;If so, set at minimum
                jmp     short mod2
mod1:
                cmp     al,63                   ;See if overflow
                jbe     mod2
                mov     al,63                   ;If so, set at maximum
mod2:
                ret
mod64_add       endp
 
;----------------------------------------------------------------------------
; GET_PALETTE buffers the current values of the VGA color registers.
;----------------------------------------------------------------------------
get_palette     proc    near
                cld                             ;Clear direction flag
                push    ax                      ;Save registers
                push    cx
                push    dx
                push    di
                push    es
 
                mov     cx,cs                   ;Point ES to the code segment
                mov     es,cx
                mov     di,offset end_res       ;Point DI to save buffer
                mov     dx,03C7h                ;Read address register
                xor     al,al                   ;Begin with register 0
                cli                             ;Disable interrupts
                out     dx,al
                mov     cx,256 * 3              ;256 color registers
                mov     dx,03C9h                ;Read data register
getp_loop1:
                in      al,dx                   ;Get color register value
                and     al,3Fh                  ;Mask off the upper 2 bits
                stosb                           ;Store it
                loop    getp_loop1              ;Loop until done
 
                sti                             ;Enable interrupts
                pop     es                      ;Restore registers and exit
                pop     di
                pop     dx
                pop     cx
                pop     ax
                ret
get_palette     endp
 
;----------------------------------------------------------------------------
; FINAL_INSTALL is the last of the resident code.
;----------------------------------------------------------------------------
final_install:
                assume  ds:code
                call    get_palette             ;Get color register values
                mov     ah,dimmer_val           ;Adjust color registers and
                call    adj_palette_2           ;  terminate
                mov     dx,(offset end_res-offset code+768+15) SHR 4
                mov     ax,3100h
                int     21h
end_res         =       $                       ;End of resident code
 
;============================================================================
; Start of non-resident section.
;============================================================================
 
alrdy_installed db      0                       ;Installed flag
other_seg       dw      0                       ;Segment of installed code
change_flag     db      0                       ;Set if dimmer or delay
                                                ;  value is modified
infomsg1        db      "Program uninstalled$"
errmsg1         db      "Program not installed$"
errmsg2         db      "Syntax: DIMMER [/U] [/V[+|-]] [/D mmm [+|-]xx]"
                db      " [[+|-]xx]$"
errmsg3         db      "Can",39,"t uninstall$"
errmsg4         db      "VGA required$"
errmsg5         db      "Intensity value must be between -63 and +63$"
errmsg6         db      "Invalid delay value$"
errmsg7         db      "Program already installed$"
errmsg8         db      "Invalid intensity value$"
 
initialize      proc    near
                assume  cs:code,ds:code
;
;See if a copy of DIMMER is already resident in memory.
;
                cld                             ;Clear direction flag
                mov     word ptr [main],0       ;Initialize fingerprint
                xor     bx,bx                   ;Zero BX for start
                mov     ax,cs                   ;Keep CS value in AX
find_copy:
                inc     bx                      ;Increment search segment
                mov     es,bx
                cmp     ax,bx                   ;Not installed if current
                je      find_copy1              ;  segment is found
                mov     si,offset main          ;Search this segment for ASCII
                mov     di,si                   ;  fingerprint.
                mov     cx,16
                repe    cmpsb
                jne     find_copy               ;Loop back if not found
                inc     alrdy_installed         ;Set installed flag
find_copy1:
                mov     other_seg,es            ;Save segment value
;
;Check to see if a mouse is present
;
                MOV     AX,0                    ; check for mouse driver
                INT     33H
                MOV     MOUSE_INST,AH           ;0=no mouse, -1=mouse installed
;
;Verify that a VGA is installed.
;
                mov     ax,1A00h                ;BIOS read display function
                int     10h
                mov     dx,offset errmsg4
                cmp     al,1Ah                  ;See if VGA present
                jne     disp_error              ;Exit on error if no VGA
;
;Parse the command line for switches.
;
                mov     si,offset command_tail+1        ;Point SI to command
parse_line_loop:                                        ;  tail in PSP
                lodsb                           ;Scan command line for / or a
                cmp     al,32                   ;  number.  Continue scanning
                je      parse_line_loop         ;  until a carriage return is
                cmp     al,13                   ;  found.
                je      parse_line_end
 
                cmp     al,"/"                  ;Is this a / character?
                jne     check_numeric           ;No, then check for numeric
                lodsb                           ;Get next character
                or      al,20h                  ;Convert to lower case
                cmp     al,"u"                  ;Check for uninstall switch
                je      uninstall_found
                cmp     al,"d"                  ;Check for delay switch
                je      delay_found
                cmp     al,"v"                  ;Check for reset delay by
                je      vidflag_found		;  video call switch.
parse_line_error:
                mov     dx,offset errmsg2       ;Syntax error
                jmp     short disp_error        ;Display message and exit
;
;Read the dimmer value from the command line if entry is numeric.
;
check_numeric:
                cmp     al,"-"                  ;Convert ASCII number into
                je      numeric_start           ;  binary.  Check for leading
                cmp     al,"+"                  ;  sign.
                je      numeric_start
                cmp     al,"0"
                jb      parse_line_error
                cmp     al,"9"
                ja      parse_line_error
                dec     si
numeric_start:
                or      change_flag,1           ;Set bit 0 in change flag
                call    setdim                  ;Read and set dimmer value
                jmp     short chk_err_and_loop  ;Check for error return
;
;Read the time delay and dimmer values from the command line.
;
vidflag_found:
                call    setvidflag              ;Modify the state of video flg
                jmp     short chk_err_and_loop  ;Check for error return
delay_found:
                or      change_flag,2           ;Set bit 1 in change flag
                call    setdelay                ;Read and set delay value
chk_err_and_loop:
                jc      disp_error
                jmp     short parse_line_loop
;
;Uninstall the program from memory.
;
uninstall_found:
                mov     dx,offset errmsg1       ;Make sure program is
                cmp     alrdy_installed,0       ;  installed and signal
                je      disp_error              ;  error if it is not
                call    remove                  ;Remove program from memory
                mov     dx,offset errmsg3
                jc      disp_error              ;Error if can't remove
                mov     dx,offset infomsg1      ;Acknowledge if removed
                call    print_string
exit:
                mov     ax,4C00h                ;Exit with RC = 0
                int     21h
;
;Process new dimmer and/or delay values now if DIMMER is already resident.
;
parse_line_end:
                cmp     alrdy_installed,0       ;Program already installed?
                je      install                 ;No, then install it
                cmp     change_flag,0           ;Changes to resident copy?
                jne     check_dimmer_change     ;Yes, then process them
                mov     dx,offset errmsg7
disp_error:
                call    print_string            ;No, then display error
                mov     ax,4C01h                ;  message and exit
                int     21h                     ;  with RC = 1
check_dimmer_change:
                test    change_flag,1           ;Adjust color registers if
                jz      check_delay_change      ;  dimmer value was changed
                push    ds
                mov     ds,other_seg            ;Point DS to installed
                assume  ds:nothing              ;  segment
                mov     ah,ds:[dimmer_val]
                call    adj_palette_1
                pop     ds
                assume  ds:code
                jmp     exit                    ;Terminate
check_delay_change:
                test    change_flag,2           ;Exit now if delay value
                jnz     exit                    ;  was modified
;
;Install a copy of DIMMER.
;
install:
                mov     ax,3508h                ;Hook into interrupt 8
                int     21h
                mov     word ptr int08h,bx
                mov     word ptr int08h[2],es
                mov     ax,2508h
                mov     dx,offset timerint
                int     21h
 
                mov     ax,3509h                ;Hook into interrupt 9
                int     21h
                mov     word ptr int09h,bx
                mov     word ptr int09h[2],es
                mov     ax,2509h
                mov     dx,offset kbint
                int     21h
 
                mov     ax,3510h                ;Hook into interrupt 10h
                int     21h
                mov     word ptr int10h,bx
                mov     word ptr int10h[2],es
                mov     ax,2510h
                mov     dx,offset videoint
                int     21h

        CMP     MOUSE_INST,-1           ; if mouse not installed
        JNE     INIT_1                  ;   then skip mouse install

                mov     ax,3533h                ;Hook into interrupt 33h
                int     21h
                mov     word ptr int33h,bx
                mov     word ptr int33h[2],es
                mov     ax,2533h
                mov     dx,offset MOUSEINT
                int     21h

INIT_1:
                mov     dx,offset program       ;Display copyright notice
                call    print_string            ;  and jump to final
                jmp     final_install           ;  install code
initialize      endp
 
;-----------------------------------------------------------------------------
; PRINT_STRING displays a DOS "$"-delimited text string with leading and
; trailing CRLFs.
;   Entry: DS:DX - String address
;-----------------------------------------------------------------------------
crlf            db      13,10,"$"
 
print_string    proc    near
                push    dx                      ;Save entry-level value of DX
                mov     ah,9                    ;Print leading CRLF
                mov     dx,offset crlf
                int     21h
                mov     ah,9                    ;Print text string
                pop     dx
                int     21h
                mov     ah,9                    ;Print trailing CRLF
                mov     dx,offset crlf
                int     21h
                ret                             ;Exit to caller
print_string    endp
 
;-----------------------------------------------------------------------------
; SETVIDFLAG modifies the video reset flag.
;   Entry: DS:SI - Address of optional sign value.
;-----------------------------------------------------------------------------
setvidflag      proc    near
                mov     al,1                    ;Assume video flag enable
                cmp     byte ptr [si],"-"       ;Check for video flag disable
                jne     setvidflag_1
                dec     al
setvidflag_1:
                mov     es,other_seg            ;Point ES to installed seg
                mov     es:[restorebyvid],al    ;Set/Reset video flag
                clc
                ret
setvidflag      endp
 
;-----------------------------------------------------------------------------
; SETDIM sets the dimmer value.
;   Entry: DS:SI - Address of first digit
;   Exit:  CF set on error (DX points to error message text)
;-----------------------------------------------------------------------------
setdim          proc    near
                mov     di,si                   ;Copy command line pointer
                call    asc2bin                 ;Convert ASCII to binary
                mov     dx,offset errmsg8       ;Exit on error
                jc      setdim_error
                cmp     byte ptr [di-1],"-"     ;Negate value if negative
                jne     setdim_1
                neg     ax
setdim_1:
                mov     dx,offset errmsg5
                cmp     ax,63                   ;Error if value is less than
                jg      setdim_error            ;  -63 or greater than +63
                cmp     ax,-63
                jl      setdim_error
 
                mov     es,other_seg            ;Point ES to installed seg
                mov     es:[dimmer_val],al      ;Record dimmer value
                clc
setdim_exit:
                ret
setdim_error:
                stc
                jmp     short setdim_exit
setdim          endp
 
;-----------------------------------------------------------------------------
; SETDELAY sets the delay counter.
;   Entry: DS:SI - Address of first character past /D switch
;   Exit:  CF set on error (DX points to error message text)
;-----------------------------------------------------------------------------
setdelay        proc    near
setdelay_l1:
                lodsb
                cmp     al,32                   ;Skip spaces
                je      setdelay_l1
                mov     dx,offset errmsg2       ;Error if no delay value
                cmp     al,13                   ;  was specified
                je      setdelay_error
 
                dec     si                      ;Back up to first character
                call    asc2bin                 ;Convert ASCII to binary
                mov     dx,offset errmsg6       ;Exit on error
                jc      setdelay_error
                mov     bx,0FFFFh               ;If delay value 0, disable
                or      ax,ax                   ;  delay counter with FFFFh
                je      delay_2
                mov     bx,ax                   ;Save delay value
setdelay_l2:
                lodsb                           ;Get next character
                cmp     al,32                   ;Skip spaces
                je      setdelay_l2
                mov     dx,offset errmsg2       ;Error if no delay value
                cmp     al,13                   ;  was specified
                je      setdelay_error
 
                mov     di,si                   ;Copy pointer to number
                cmp     al,"-"                  ;Check for leading sign
                je      setdelay_1              ;  identifier
                cmp     al,"+"
                je      setdelay_1
                dec     si                      ;Back up to first character
setdelay_1:
                push    bx                      ;Save delay value
                call    asc2bin                 ;ASCII --> binary
                pop     bx                      ;Retrieve delay value
                mov     dx,offset errmsg8       ;Exit on error
                jc      setdelay_error
                cmp     byte ptr [di-1],"-"     ;Negate value if negative
                jne     delay_1
                neg     ax
delay_1:
                mov     dx,offset errmsg5       ;Check to see if the value
                cmp     ax,63                   ;  is out of range
                jg      setdelay_error
                cmp     ax,-63
                jl      setdelay_error
delay_2:
                mov     es,other_seg            ;Load new delay and dimmer
                mov     es:[delaydimval],al     ;  values into the
                mov     es:[wait_time],bx       ;  program
                MOV     ES:[SAVE_WAIT],BX
                mov     es:[dim_counter],bx
                mov     es:[second_cnt],1092
                clc
setdelay_exit:
                ret
setdelay_error:
                stc
                jmp     short setdelay_exit
setdelay        endp
 
;-----------------------------------------------------------------------------
; REMOVE removes a resident copy of the program from memory.
;   Exit: CF set on error
;-----------------------------------------------------------------------------

remove_error:
                stc
                jmp     remove_exit1

remove          proc    near
                cmp     alrdy_installed,0       ;See if installed
                je      remove_error            ;No, error

                mov     ax,3508h                ;Get timer vector
                int     21h
                mov     ax,es                   ;Check to make sure timer
                cmp     ax,other_seg            ;  vector not modified
                jne     remove_error
 
                mov     ax,3509h                ;Get keyboard vector
                int     21h
                mov     ax,es                   ;Check to make sure keyboard
                cmp     ax,other_seg            ;  vector not modified
                jne     remove_error
 
                mov     ax,3510h                ;Get video vector
                int     21h
                mov     ax,es                   ;Check to make sure video
                cmp     ax,other_seg            ;  vector not modified
                jne     remove_error
 
        CMP     MOUSE_INST,-1           ; if mouse not installed
        JNE     REMOVE_1                ;   then skip mouse segment check

                mov     ax,3533h                ;Get mouse vector
                int     21h
                mov     ax,es                   ;Check to make sure video
                cmp     ax,other_seg            ;  vector not modified
                jne     remove_error
 
REMOVE_1:
                push    ds
                lds     dx,es:[int08h]          ;Get old interrupt 8 vector
                mov     ax,2508h                ;Set interrupt
                int     21h
                lds     dx,es:[int09h]          ;Get old interrupt 9 vector
                mov     ax,2509h                ;Set interrupt
                int     21h
                lds     dx,es:[int10h]          ;Get old interrupt 10 vector
                mov     ax,2510h                ;Set interrupt
                int     21h

        CMP     MOUSE_INST,-1           ; if mouse not installed
        JNE     REMOVE_2                ;   then skip mouse remove

                lds     dx,es:[int33h]          ;Get old interrupt 33 vector
                mov     ax,2533h                ;Set interrupt
                int     21h
REMOVE_2:
                pop     ds
 
                mov     cx,es:[env_segment]
                mov     ah,49h                  ;Free PSP block
                int     21h
                mov     es,cx                   ;Free environment block
                mov     ah,49h
                int     21h
remove_exit:    
                clc
remove_exit1:
                ret

remove          endp
 
;-----------------------------------------------------------------------------
; ASC2BIN Converts an ASCII number pointed to by SI to a hex value.
;   Entry: SI = pointer to ASCII number
;   Exit:  AX = binary value
;          CF set on error
;-----------------------------------------------------------------------------
ten             dw      10
 
asc2bin         proc near
                xor     ax,ax                   ;Clear accumulator
                xor     bx,bx                   ;Clear BX
asc_loop:
                mov     bl,[si]                 ;Get ASCII character
                cmp     bl,13                   ;Done if carriage return or
                je      asc_exit                ;  space encountered
                cmp     bl,32
                je      asc_exit
                inc     si
                sub     bl,"0"                  ;ASCII --> binary
                jb      asc_error               ;Error if binary value is
                cmp     bl,9                    ;  less than 0 or greater
                ja      asc_error               ;  than 9
                mul     ten                     ;Multiply accumulator by 10
                add     ax,bx                   ;Add last digit to sum
                jmp     short asc_loop          ;Loop until done
asc_exit:
                clc
asc_exit1:
                ret
asc_error:
                stc
                jmp     short asc_exit1
asc2bin         endp
 
code            ends
                end     main
