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push dx
push di
mov di, 80 ; load di with columns per row
mov ax, [bp+8] ; load ax with row number
mul di ; multiply with columns per row
mov di, ax ; save result in di
add di, [bp+6] ; add column number
shl di, 1 ; turn into byte count
add di, 8 ; to end of number location
mov ax, 0xb800
mov es, ax ; point es to video base
mov ax, [bp+4] ; load number in ax
mov bx, 16 ; use base 16 for division
mov cx, 4 ; initialize count of digits
nextdigit: mov dx, 0 ; zero upper half of dividend
div bx ; divide by 10
add dl, 0x30 ; convert digit into ascii value
cmp dl, 0x39 ; is the digit an alphabet
jbe skipalpha ; no, skip addition
add dl, 7 ; yes, make in alphabet code
skipalpha: mov dh, 0x07 ; attach normal attribute
mov [es:di], dx ; print char on screen
sub di, 2 ; to previous screen location
loop nextdigit ; if no divide it again
pop di
pop dx
pop cx
pop bx
pop ax
pop es
pop bp
ret 6
; subroutine to print a string
; takes row no, column no, address of string, and its length
; as parameters
printstr: push bp
mov bp, sp
push es
push ax
push bx
push cx
push dx
push si
push di
mov ax, 0xb800
mov es, ax ; point es to video base
mov di, 80 ; load di with columns per row
mov ax, [bp+10] ; load ax with row number
mul di ; multiply with columns per row
mov di, ax ; save result in di
add di, [bp+8] ; add column number
shl di, 1 ; turn into byte count
mov si, [bp+6] ; string to be printed
mov cx, [bp+4] ; length of string
mov ah, 0x07 ; normal attribute is fixed
nextchar: mov al, [si] ; load next char of string
mov [es:di], ax ; show next char on screen
add di, 2 ; move to next screen location
add si, 1 ; move to next char
loop nextchar ; repeat the operation cx times
pop di
pop si
pop dx
pop cx
pop bx
pop ax
