.model small

.code

public write_hex

;ON ENTRY DL CONTAINS THE HEX BYTE TO BE WRITTEN

;USES write_hex_digit PROCEDURE

write_hex proc

; does the masking of dl; first higher order then lower

; order

push dx

shr dl,4

and dl,0fh

call write_hex_digit

pop dx

push dx

and dl,0fh

call write_hex_digit

pop dx

ret

write_hex endp

public write_hex_digit

;ON ENTRY LOWER NIBBLE OF DL CONTAINS NUMBER TO BE PRINTED

; IN HEX

;USES write_char PROCEDURE

write_hex_digit proc

; does the convertion of contents of dl into hex ascii char

push dx

add dl,"0"

cmp dl,"9"

jbe less

add dl,07h

less : call write_char

pop dx

ret

write_hex_digit endp

public write_char

extrn cursor_right:proc

write_char proc

; just calls the DOS function call for printing the

; char in dl

push ax

push bx

push cx

push dx

mov ah,9

mov bh,0

mov cx,1

mov al,dl

mov bl,7

int 10h

call cursor_right

pop dx

pop cx

pop bx

pop ax

ret

write_char endp

public write_decimal

;ON ENTRY DX CONTAINS NUMBER TO BE PRINTED IN DECIMAL

;USED write_hex PROCEDURE

write_decimal proc

push dx

push ax

push cx

push si

mov ax,dx

mov si,10d

xor cx,cx

non_zero : xor dx,dx

div si

push dx

inc cx

or ax,ax

jne non_zero

write_digit_loop: pop dx

call write_hex_digit

loop write_digit_loop

decimal_end: pop si

pop cx

pop ax

pop dx

ret

write_decimal endp

public write_char_n_times

;on entry dl contains the char to be printed

;cx contains number of times it is to be printed

write_char_n_times proc

push cx

n_times : call write_char

loop n_times

pop cx

ret

write_char_n_times endp

public write_pattern

;on entry ds:dx contains the address of the pattern

;to draw

write_pattern proc

push ax

push cx

push dx

push si

pushf

cld

mov si,dx

pattern_loop: lodsb

or al,al

jz end_pattern

mov dl,al

lodsb

mov cl,al

xor ch,ch

call write_char_n_times

jmp pattern_loop

end_pattern: popf

pop si

pop dx

pop cx

pop ax

ret

write_pattern endp

public write_string

write_string proc

push ax

push dx

push si

pushf

cld

mov si,dx

string_loop: lodsb

or al,al

jz end_of_string

mov dl,dl

call write_char

jmp string_loop

end_of_string: popf

pop si

pop dx

pop ax

ret

write_string endp

end