org 0x100

		mov ax, 0x3D00
		mov dx, infile
		int 0x21
		jc err

		mov [fd], ax

loop:		call getc
		jc end
		cmp dl, 26
		je end
		mov ah, 2
		int 0x21
		jmp loop

end:		ret

err:		mov dx, ax

dumpdx:		; setup bx and ah for int 10h call
		xor bx, bx
		mov ah, 0x0e
		mov cl, 4
		; this double-call is essentially a 4 times repeating loop
		call dmpdx1
dmpdx1:		call dmpdx2
dmpdx2:		; grab highest nibble from dx
		mov al, dh
		; remove highest nibble from dx
		shl dx, cl
		; shift away second-highest nibble that we accidentally copied
		shr al, cl
		; map 0-9 to ascii codes for '0' to '9'
		add al, 0x30
		; if result is larger than '9', ...
		cmp al, 0x3a
		jl dmpdx3
		; ... add 7 so we continue at 'A'
		add al, 7
dmpdx3:		int 0x10
		ret

		; read a character from the input file into DL
getc:		mov dl, 26
		push dx
		mov ah, 0x3f
		mov bx, [fd]
		mov cx, 1
		mov dx, sp
		int 0x21
		pop dx
		ret

infile:		db "com/a86.asm", 0

fd:		dw 0