From 5382edc2aef6ea70f48f41ee31eacd2e92543cbd Mon Sep 17 00:00:00 2001
From: Ain <41307858+nero@users.noreply.github.com>
Date: Sat, 4 Jul 2020 10:35:38 +0200
Subject: [PATCH] Improve ordering of binary data in kernel

---
 boot/kernel.asm | 133 +++++++++++++++++++++++++-----------------------
 1 file changed, 68 insertions(+), 65 deletions(-)

diff --git a/boot/kernel.asm b/boot/kernel.asm
index 51be791..695d5cf 100644
--- a/boot/kernel.asm
+++ b/boot/kernel.asm
@@ -1,31 +1,69 @@
-	cpu 8086
-	org 0x500
-	jmp 0:(init+0x7C00-$$)
+		cpu 8086
+		org 0x500
 
-%include "kernel/fd.asm"
-%include "kernel/con.asm"
-%include "inc/bpb.asm"
-%include "inc/mbr.asm"
+%include	"inc/bpb.asm"
+%include	"inc/mbr.asm"
 
-	; Far call via interrupt vector
-	%macro intcall 1
-	call far [cs:%1*4]
-	%endmacro
+		; kernel stack size in words
+%define		stacksize 512
 
-	; Far jump via interrupt vector
-	%macro intjmp 1
-	jmp far [cs:%1*4]
-	%endmacro
+init:		cli
+		xor ax, ax
+		mov ds, ax
+		mov es, ax
+		mov ss, ax
+		mov sp, ( stack+stacksize )
 
-	; stack size
-	%define stacks 512
+		; relocate
+		mov si, 0x7C00
+		mov di, $$
+		mov cx, (_end-$$)
+		rep movsb
+
+		jmp 0:main
+
+main:		; zero out first 64kb except our code
+		; bss and boot sector area gets cleared by this
+		mov cx, di
+		neg cx
+		xor ax, ax
+		rep stosb
+
+		; install interrupt vectors
+		mov si, vects
+		mov di, (0x20*4)
+		mov cx, 0x0A
+intlp:		movsw
+		mov ax, cs
+		stosw
+		loop intlp
+
+		; file descriptor 0 = CON
+		mov word [fd_table], con_ftab
+
+		; print banner
+		mov dx, banner
+		mov cx, 13
+		mov bx, 0
+		call fd_write
+
+		call dnconv
+		mov al, dl
+		call select
+		call load_bpb
+
+loop:		int 0x28
+		jmp loop
+
+section .data
 
 banner:	db "rdos loaded", 0xA, 0xD, '$'
 
+section .text
+
 	; Alias for Int 21h,AH=0h
 int20h:	xor ah, ah
-	; allow extenders to get away with only hooking 21h
-	intjmp 0x21
+	jmp far [cs:0x21*4]
 
 int21h:	; inside of kernel, direction always goes up
 	; the iret will restore it to the user value later
@@ -53,6 +91,8 @@ iretfl:	push ax
 iret:	iret
 retf:	retf
 
+section .data
+
 	; Subfunction ptr
 	; this is used as extra register in int21h
 sfptr:	dw 0
@@ -78,6 +118,8 @@ sftab:	dw sferr, getc, putc, sferr
 	dw sferr, sferr, sferr, sferr
 	dw sferr, sferr, sferr, sferr
 
+section .text
+
 	; OUT	al	character read
 getc:	xor ax, ax
 	int 0x16
@@ -195,59 +237,20 @@ fputc:	push ax
 	pop ax
 	iret
 
+	%include "kernel/fd.asm"
+	%include "kernel/con.asm"
+
 	%include "kernel/diskio.asm"
 	%include "kernel/fat.asm"
 
+section .data
+
 vects:	dw int20h, int21h, retf, retf
 	dw retf, retf, retf, int20h
 	dw idle, fputc
 
-main:	; zero out first 64kb except our code
-	; bss and boot sector area gets cleared by this
-	mov di, init
-	mov cx, di
-	neg cx
-	xor ax, ax
-	rep movsb
-
-	; install interrupt vectors
-	mov si, vects
-	mov di, (0x20*4)
-	mov cx, 0x0A
-intlp:	movsw
-	mov ax, cs
-	stosw
-	loop intlp
-
-	; print banner
-	mov dx, banner
-	mov cx, 13
-	mov bx, 0
-	call con_write
-
-	call dnconv
-	mov al, dl
-	call select
-	call load_bpb
-
-loop:	int 0x28
-	jmp loop
-
-init:	cli
-	xor ax, ax
-	mov ds, ax
-	mov es, ax
-	mov ss, ax
-	mov sp, ( stack+stacks )
-
-	; relocate
-	mov si, 0x7C00
-	mov di, $$
-	mov cx, (init-$$)
-	rep movsb
-
-	jmp 0:main
+_end:	dw 0x55AA, 0x55AA
 
 section .bss
 	; stack to be used during init and disk i/o
-stack:	resw stacks
+stack:	resw stacksize