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[bits 16]
BLANK:
db 0x12
SPACE:
db " ",0
;print_string routine ([bx])
;this routine will print a null terminated string at [bx] to the screen.
print_string:
pusha ;push all registers
mov ah,0x0e
print_string_loop:
;check if value at [bx] is "\0" (end of string)
mov cl,[bx]
cmp cl,0
je print_string_finish
;otherwise instruct BIOS to print the current char
mov al,cl
int 0x10
;proceed with next char
inc bx
jmp print_string_loop
print_string_finish:
popa ;pop all registers
ret ;return to caller
print_clear:
pusha
mov ah,0x6 ;func
mov al,0 ;scroll one line
mov bh,[BLANK] ;blank char
mov ch,0 ;upper left corner
mov cl,0
mov dh,20 ;lower right corner
mov dl,40
int 0x10
mov ah,0x2
mov bh,0
mov dl,0
mov dh,20
int 0x10
popa
print_nextline:
pusha
mov ah,0x6 ;func
mov al,1 ;scroll one line
mov bh,[BLANK] ;blank char
mov ch,0 ;upper left corner
mov cl,0
mov dh,20 ;lower right corner
mov dl,40
int 0x10
mov ah,0x3
mov bh,0
int 0x10
mov ah,0x2
mov dl,0
int 0x10
mov bx,SPACE
call print_string
popa
ret
;print byte from al to screen
print_hex_byte:
pusha
mov [.temp],al
shr al,4
cmp al,10
sbb al,69h
das
mov ah,0Eh
int 10h
mov al,[.temp]
ror al,4
shr al,4
cmp al,10
sbb al,69h
das
mov ah,0Eh
int 10h
popa
ret
.temp db 0
|
