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DISPLAY.ASM
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;--------------------------------------------------------------------
;
; display.asm
;
; procedures for displaying integer output
;
;--------------------------------------------------------------------
.model small
PUBLIC dispspace
PUBLIC disp0x
PUBLIC dispCR
PUBLIC dispd16
PUBLIC disph16
.code
;--------------------------------------------------------------------
disph16 PROC ; display a word in hex
; word to display is in ax
push ax
push bx
push cx
push dx
call disp0x ; display the initial 0x
mov bx, ax
shr ax, 12 ; ax = most significant nibble of n
call disph
shl ax, 12
sub bx, ax ; bx = 3 least significant nibbles of n
mov ax, bx
shr ax, 8 ; ax = 2nd most significant nibble of n
call disph
shl ax, 8
sub bx, ax ; bx = 2 least significant nibbles of n
mov ax, bx
shr ax, 4 ; ax = 2nd least signicant nibble of n
call disph
shl ax, 4
sub bx, ax ; bx = least significant nibble of n
mov ax, bx ; ax = least significant nibble of n
call disph
pop dx
pop cx
pop bx
pop ax
ret
disph16 endp
;---------------------------------------------------------------------
disph PROC ; display one hex digit of a number
; nibble to display is in al
push ax
push dx
add ax, 30h ; convert to ascii
cmp ax, 39h ; check to see if A-F
jle dig09
add ax, 07h
dig09:
mov dl, al ; DOS WRITE TO STDOUT
mov ah, 02h
int 21h
pop dx
pop ax
ret
disph endp
;--------------------------------------------------------------------
dispd16 PROC ; display a word in decimal
; word to display is in ax
push ax
push bx
push cx
push dx
mov dx, 0000h ; set up for div
mov cx, 2710h
div cx ; divide ax by 10000d to get first digit
mov bx, dx ; put remainder in bx
call dispd
mov dx, 0000h ; set up for div
mov ax, bx ; the remainder from previous is now a
; four digit decimal number
mov cx, 03E8h
div cx ; divide ax by 1000d to get second digit
mov bx, dx ; put remainder in bx
call dispd
mov dx, 0000h ; set up for div
mov ax, bx ; the remainder from previous is now a
; three digit decimal number
mov cx, 0064h
div cx ; divide ax by 100d to get second digit
mov bx, dx ; put remainder in bx
call dispd
mov dx, 0000h ; set up for div
mov ax, bx ; the remainder from previous is now a
; two digit decimal number
mov cx, 000Ah
div cx ; divide ax by 10d to get second digit
mov bx, dx ; put remainder in bx
call dispd
mov dx, 0000h
mov ax, bx ; the remainder from previous is now a
; one digit decimal number
call dispd
pop dx
pop cx
pop bx
pop ax
ret
dispd16 endp
;--------------------------------------------------------------------
dispd PROC ; display a decimal digit
; digit to display is in ax
push ax
push dx
add ax, 30h ; convert to ASCII
mov dl, al ; DOS WRITE TO STDOUT
mov ah, 02h
int 21h
pop dx
pop ax
ret
dispd endp
;--------------------------------------------------------------------
dispspace PROC ; display a space
push ax
push dx
mov dl, 20h
mov ah, 02h
int 21h
pop dx
pop ax
ret
dispspace endp
;--------------------------------------------------------------------
disp0x PROC ; display hex indicator
push ax
push dx
mov dl, 30h ; display 0
mov ah, 02h
int 21h
mov dl, 78h ; display x
mov ah, 02h
int 21h
pop dx
pop ax
ret
disp0x endp
;--------------------------------------------------------------------
dispCR PROC ; display a CR
push ax
push dx
mov dl, 0Dh ; display CR
mov ah, 02h
int 21h
mov dl, 0Ah ; display NL
mov ah, 02h
int 21h
pop dx
pop ax
ret
dispCR endp
;--------------------------------------------------------------------
end