From aff8076b22d2b87498ffd878fe71b8bb2bae3c94 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Thu, 27 Jan 2022 02:46:30 +0500
Subject: [PATCH] Use C preprocessor

---
 build.sh         |  4 ++--
 src/x86_stage1.S | 15 +++++++++++----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/build.sh b/build.sh
index d2a18da..e0d506f 100755
--- a/build.sh
+++ b/build.sh
@@ -5,8 +5,8 @@ set -e
 BIN='../cross/root/bin'
 CROSS="$BIN/i386-elf-"
 
-${CROSS}as -c src/x86_stage1.S -o src/x86_stage1.o
-${CROSS}as -c src/x86_stage2.S -o src/x86_stage2.o
+${CROSS}gcc -c src/x86_stage1.S -o src/x86_stage1.o
+${CROSS}gcc -c src/x86_stage2.S -o src/x86_stage2.o
 ${CROSS}ld -Ttext 200000 --oformat binary -o src/x86_stage1.bin src/x86_stage1.o
 ${CROSS}ld -Ttext 200000 --oformat binary -o src/x86_stage2.bin src/x86_stage2.o
 ./testyboot mbr mbr.bin src/x86_stage1.bin
diff --git a/src/x86_stage1.S b/src/x86_stage1.S
index cbcfb3f..0d090f5 100644
--- a/src/x86_stage1.S
+++ b/src/x86_stage1.S
@@ -1,11 +1,18 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+
+#define STACK_ADDR  0x2000
+#define STAGE1_ADDR 0x7c00
+#define STAGE2_ADDR 0x7e00
+
+#define ADDRESS(x) (x - _start + STAGE1_ADDR)
+
 .code16
 .global _start
 .section .text
 _start:
-    ljmp $0, $(start - _start + 0x7c00)
+    ljmp $0, $ADDRESS(start)
 
 disk:
     .byte 0
@@ -18,9 +25,9 @@ start:
     mov %ax, %es
     mov %ax, %fs
     mov %ax, %gs
-    mov $0x2000, %sp
+    mov $STACK_ADDR, %sp
 
-    mov %dl, (disk - _start + 0x7c00)
+    mov %dl, ADDRESS(disk)
 
     mov $0x02,   %ah
     mov $1,      %al /* Sectors count       */
@@ -75,7 +82,7 @@ start:
     mov $'\n', %al
     int $0x10
 
-    ljmp $0, $0x7e00
+    ljmp $0, $STAGE2_ADDR
 
 hang:
     cli