rdos/com/a86.asm

		org 0x100

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

		mov [fd], ax

		call getline

		mov dx, [line_length]
		call dumpdx

		mov si, line_buffer
		mov cx, [line_length]
		mov ah, 2
l03:		lodsb
		mov dl, al
		int 0x21
		loop l03

end:		ret

line_num:	dw 1

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

getline:	mov word [line_length], 0
		mov di, line_buffer
		mov cx, line_buflen
l02:		push cx
		call getc
		pop cx
		mov al, dl
		cmp al, 0x0A
		je l01
		cmp al, 0x0D
		je l01
		cmp al, 0x1A
		je l01
		inc word [line_length]
		loop l02

l01:		ret

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

line_buflen:	equ 0x100
line_length:	dw 0 ; valid bytes in buffer
line_prefix:	times 16 db " "
line_buffer:	times line_buflen db 0

fd:		dw 0