rdos/src/sys.asm

fcb1	equ 0x5C

	org 0x100
	jmp main

%include "scan.inc"
%include "print.inc"

main	mov di, 0x81
	mov al, 0x20
	mov ch, 0
	mov cl, [0x80]
	repe scasb
	repne scasb
	mov si, di
	call lodnum
	mov dx, ax
	test dx, ~0x83
	jnz drverr
	test dl, 0x80
	jz floppy
	call drverr

drverr	call putsh
	db "Failed to access drive", 0x0A, 0x0D, 0
	int 0x20

floppy	mov ax, 0x0201
	mov cx, 0x0001
	mov dh, 0
	mov bx, bs
	int 0x13
	jc drverr
	mov ax, [bs+0x18]
	call debug
	ret

	mov dx, fcb1
	mov ah, 0xF
	int 0x21
	test al, al
	jz .fok
.ferr	call putsh
	db "Failed to read input file", 0x0A, 0x0D, 0
	ret
.fok	mov si, prog
	; apply our target address
.rloop	mov dx, si
	mov ah, 0x1A
	int 0x21
	; increment address for next iteration
	add si, 0x80
	; do a read
	mov dx, fcb1
	mov ah, 0x14
	int 0x21
	; success: continue
	cmp al, 0
	jz .rloop
	; eof: break
	cmp al, 1
	jz .cok
	; segment wrap: fail
	cmp al, 2
	jz .ferr
	; we assume al=3: eof
.cok	nop
	mov ax, si
	sub ax, args
	call debug
	call putsh
	db "yay", 0x0A,0x0D,0

	ret
;	mov ax, 0x0201
;	mov cx, 0x0001
;	mov dh, 0
;	mov bx, bs
;	int 0x13
;	mov ax, [bs+0x18]
;.ret	ret

	align 2
bs	equ $
psp	equ bs + 0x200
args	equ psp + 0x80
prog	equ psp + 0x100