Drop MCBs as mean to manage memory

Makefile

@@ -48,8 +48,6 @@ vga11.com: cp437.bin
 %.bs: boot/%.asm
 	$(NASM) $(NASM_ARGS) -o $@ $<
 
-kernel.bs: kernel/*.asm
-
 # Special case: variations of FAT vbr
 fat1.bs: boot/fat.asm
 	$(NASM) $(NASM_ARGS) -DFAT12 -DCHS -o $@ $<

boot/kernel.asm

@@ -1,9 +1,8 @@
 	cpu 8086
-	org 0
+	org 0x500
-	jmp 0x07C0:init
+	jmp init
 
 	%include "inc/bpb.asm"
-	%include "kernel/mcb.asm"
 
 banner:	db "rdos", 0xA, 0xD, 0
 
@@ -223,21 +222,7 @@ ldbpb:	push ds
 	pop ds
 	ret
 
-init:	cli
+main:	mov si, banner
-	mov ax, cs
-	mov ds, ax
-	mov es, ax
-	mov ss, ax
-	xor sp, sp
-
-	call dnconv
-	call select
-
-	call mcb_init
-
-main:	push cs
-	pop ds
-	mov si, banner
 	mov ah, 0x0e
 	xor bx, bx
 loop:	lodsb
@@ -248,3 +233,19 @@ loop:	lodsb
 end:	hlt
 	jmp end
 
+init:	cli
+	xor ax, ax
+	mov ds, ax
+	mov es, ax
+	mov ss, ax
+	xor sp, sp
+
+	mov si, 0x7C00
+	mov di, $$
+	mov cx, (init-$$)
+	rep movsb
+
+	call dnconv
+	call select
+
+	jmp 0:main

kernel/mcb.asm

@@ -1,70 +0,0 @@
-	; First MCB block is always at 00540
-mcb_first:
-	mov ax, 0x54
-	mov ds, ax
-	ret
-
-mcb_init:
-	call mcb_first
-	mov dx, ds
-	inc dx
-	xor si, si
-	int 0x12
-	mov cl, 6
-	shl ax, cl
-	sub ax, dx
-	mov byte [si+0], 'Z'
-	mov word [si+1], 0
-	mov word [si+3], ax
-	mov dx, cs
-	call mcb_split
-	mov word [si+1], 8
-	ret
-
-	; split mcb block into two
-	; IN	dx	segment of second block
-mcb_split:
-	call mcb_find
-	dec dx
-	push dx
-	; Calculate size of first block
-	; dx = dx - ds - 1
-	stc
-	mov ax, ds
-	sbb dx, ax
-	;
-	push dx
-	; swap old size with new size
-	xchg dx, [si+3]
-	; if current mcb is last, its not anymore
-	mov cl, 'M'
-	xchg cl, byte [si+0]
-	; advance DS to begin of first block
-	pop ax
-	stc
-	sbb dx, ax
-	pop ax
-	mov ds, ax
-	; write MCB data
-	mov byte [si+0], cl
-	mov word [si+1], 0
-	mov word [si+3], dx
-	ret
-
-	; IN	dx	segment we look for
-	; OUT	ds	segment where mcb starts
-mcb_find:
-	call mcb_first
-	xor si, si
-.loop:	stc
-	adc ax, [si+3]
-	cmp dx, ax
-	jc .found
-	cmp byte [si+0], 'Z'
-	jz .fail
-	mov ds, ax
-	jmp .loop
-.fail:	stc
-	ret
-.found:	clc
-	ret