From e0ab3e5c1abce531b37420822f8ab1e63f2d43b3 Mon Sep 17 00:00:00 2001
From: d0p1 <contact@d0p1.eu>
Date: Mon, 29 Jul 2024 17:51:41 +0200
Subject: [PATCH] refactor(boot): create fat_read_bpb func

---
 boot/loader/Makefile   |  1 +
 boot/loader/fat.inc    | 30 ++++++++++++++++++++++++++++++
 boot/loader/loader.asm | 26 ++------------------------
 3 files changed, 33 insertions(+), 24 deletions(-)
 create mode 100644 boot/loader/fat.inc

diff --git a/boot/loader/Makefile b/boot/loader/Makefile
index d560bb8..43d6f7a 100644
--- a/boot/loader/Makefile
+++ b/boot/loader/Makefile
@@ -5,6 +5,7 @@ LOADER_SRCS	= loader.asm \
 				../common/bootinfo.inc \
 				../../kernel/sys/bootinfo.inc \
 				../../kernel/sys/register.inc \
+				fat.inc \
 				video.inc \
 				memory.inc \
 				logger.inc \
diff --git a/boot/loader/fat.inc b/boot/loader/fat.inc
new file mode 100644
index 0000000..3bad234
--- /dev/null
+++ b/boot/loader/fat.inc
@@ -0,0 +1,30 @@
+	;; File: fat.inc
+
+include '../common/fat12.inc'
+
+fat_read_bpb:
+	mov ax, DISK_BUFFER/0x10
+	mov es, ax
+	xor bx, bx
+	mov ax, 0
+	mov cx, 1
+	call disk_read_sectors
+
+	mov word ax, [DISK_BUFFER + fat_bpb.sects_per_track]
+	mov word [sectors_per_track], ax
+	mov word ax, [DISK_BUFFER + fat_bpb.heads_per_cyl]
+	mov word [heads_per_cylinder], ax
+	mov word ax, [DISK_BUFFER + fat_bpb.bytes_per_sects]
+	mov word [bytes_per_sector], ax
+	mov word ax, [DISK_BUFFER + fat_bpb.sects_per_FAT]
+	mov word [sectors_per_FAT], ax
+	mov byte al, [DISK_BUFFER + fat_bpb.FAT_count]
+	mov byte [FAT_count], al
+	mov word ax, [DISK_BUFFER + fat_bpb.reserved_sects]
+	mov word [reserved_sectors], ax
+	mov word ax, [DISK_BUFFER + fat_bpb.root_dir_entries]
+	mov word [root_dir_entries], ax
+	mov byte al, [DISK_BUFFER + fat_bpb.sects_per_clust]
+	mov byte [sectors_per_cluster], al
+	ret
+
diff --git a/boot/loader/loader.asm b/boot/loader/loader.asm
index 9fec956..31f2a79 100644
--- a/boot/loader/loader.asm
+++ b/boot/loader/loader.asm
@@ -80,29 +80,7 @@ _start:
 	; for now fat12 is asumed
 .fat_fallback:
 	; get bpb
-	mov ax, DISK_BUFFER/0x10
-	mov es, ax
-	xor bx, bx
-	mov ax, 0
-	mov cx, 1
-	call disk_read_sectors
-
-	mov word ax, [DISK_BUFFER + fat_bpb.sects_per_track]
-	mov word [sectors_per_track], ax
-	mov word ax, [DISK_BUFFER + fat_bpb.heads_per_cyl]
-	mov word [heads_per_cylinder], ax
-	mov word ax, [DISK_BUFFER + fat_bpb.bytes_per_sects]
-	mov word [bytes_per_sector], ax
-	mov word ax, [DISK_BUFFER + fat_bpb.sects_per_FAT]
-	mov word [sectors_per_FAT], ax
-	mov byte al, [DISK_BUFFER + fat_bpb.FAT_count]
-	mov byte [FAT_count], al
-	mov word ax, [DISK_BUFFER + fat_bpb.reserved_sects]
-	mov word [reserved_sectors], ax
-	mov word ax, [DISK_BUFFER + fat_bpb.root_dir_entries]
-	mov word [root_dir_entries], ax
-	mov byte al, [DISK_BUFFER + fat_bpb.sects_per_clust]
-	mov byte [sectors_per_cluster], al
+	call fat_read_bpb
 
 	call fat_load_root
 
@@ -177,7 +155,7 @@ _start:
 
 	include 'a20.inc'
 	include '../common/bios.inc'
-	include '../common/fat12.inc'
+	include 'fat.inc'
 	include 'disk.inc'
 	include 'logger.inc'
 	include 'memory.inc'