rdos/boot/kernel.asm

		cpu 8086
		org 0x0700

%include	"inc/bpb.asm"
%include	"inc/mbr.asm"
%include	"inc/fcb.asm"
%include	"inc/dpt.asm"

init:		cli
		xor ax, ax
		mov ds, ax
		mov es, ax
		mov ss, ax
		mov sp, ax

		mov si, 0x7C00
		; relocate to 00700
		mov di, text_start
		mov cx, text_length + rodata_length + data_length
		rep movsb
		; clear out bss section
		mov cx, bss_length
		rep stosb
		; jump to copy
		call 0:relinit

section .rodata

%define V 0x %+ VERSION
version:	dd V

section .text

relinit:	; print banner
		push word [version]
		push word [version+2]
		call printf
		db "RDOS ",2,2, 0x0A, 0x0D, 0

		push dx
		push ds
		call dinit
		pop ds
		pop dx

		mov word [0x21*4], int21
		mov word [0x21*4+2], cs
		; set current PSP, directly after us
		mov ax, stack
		mov cl, 4
		shr ax, cl
		mov word [curpsp], ax

		cmp dl, 0x80
		jc .k
		sub dl, (0x80-2)
.k:		call setdd

		mov ah, 2
		mov dl, 0x37
		int 0x21

		mov dx, testfcb
		mov ah, 0xF
		int 0x21

restart:
hlt:		hlt
		jmp hlt

%include	"kernel/syscall.asm"
%include	"kernel/char.asm"
%include	"kernel/fcb.asm"
%include	"kernel/drive.asm"
%include	"kernel/printf.asm"

section .data

testfcb:	db 0
		db "HELLO   ", "COM"
		times 30 db 0

section .text

text_start	equ  $$
text_length	equ  $-$$

section .rodata

rodata_start	equ  $$
rodata_length	equ  $-$$

section .data

data_start	equ  $$
data_length	equ  $-$$

section .bss

		resw 256 ; 512b kern stack
		alignb 16
stack:		; stack grows into this ^
		; this is also the end marker
		; programs with their psp start here

bss_start	equ  $$
bss_length	equ  $-$$