Restructure the bootloader

[nameless-os.git] / boot / x86 / protected.s

diff --git a/boot.s b/boot/x86/protected.s
similarity index 64%
rename from boot.s
rename to boot/x86/protected.s
index 6181a73528610dcaf7c18ea6beb51dbf03865ffe..d1c7eea34df31ac1a191c26bc2abeb6bb45924d6 100644 (file)
--- a/boot.s
+++ b/boot/x86/protected.s
@@ -1,50 +1,6 @@
-       bits 16 ; boot sectors run in real mode
-       org 7C00h ; BIOS loads us at 0x7c00
+; Everything between real mode and the C kernel
 
-KERNEL_OFFSET equ 1000h ; where we will load our kernel
-
-       mov [BOOT_DRIVE], dl ; BIOS puts the number of our boot drive in dl, so we will want to remember this
-
-       mov bp, 9000h ; initialize stack at a spot sufficiently distanced from this code
-       mov sp, bp
-
-       mov di, 0
-
-       xor ax, ax ; clear accumulator
-       int 13h ; BIOS disk services, with a cleared accumulator this will reset the disk controller
-       jc reset_error ; halt if controller reset fails
-
-       mov ah, 2 ; instruct BIOS's interrupt 13h to read sectors
-       mov al, 10 ; load 10 sectors, might be excessive (for now) but it's still good to do so
-       xor ch, ch ; read from 1st cylinder
-       mov cl, 2 ; start reading from 2nd sector, right after the boot sector
-       xor dh, dh ; read from 1st head
-       xor bx, bx ; clear B register
-       mov es, bx ; clear extended segment
-       mov bx, KERNEL_OFFSET ; put the sectors in our desired offset
-       ; dl holds the number of the drive to read from, but BIOS already filled this in
-       int 13h ; do the read
-       jc read_error ; halt if read fails
-       cmp al, 10 ; make sure we actually read 10 sectors
-       jl read_error ; halt if we didn't
-       jmp switch_to_pm ; if all is good, begin the switch to 32-bit protected mode
-
-reset_error
-       mov bx, 0B800h
-       mov es, bx
-       mov byte [es:di], '1'
-       jmp halt
-
-read_error
-       mov bx, 0B800h
-       mov es, bx
-       mov byte [es:di], '2'
-       jmp halt
-
-       call switch_to_pm
-
-halt
-       jmp $
+       bits 16
 
 switch_to_pm
        mov bx, 0B800h
@@ -143,7 +99,3 @@ gdt_desc
 CODE_SEG equ code_seg - gdt_start
 DATA_SEG equ data_seg - gdt_start
 
-BOOT_DRIVE db 0 ; reserve a spot in RAM for our boot drive variable
-
-       times 510-($-$$) db 0
-       dw 0AA55h ; MBR signature