Aren
/
toaruos
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Optimization

This commit is contained in:
K. Lange 2018-03-06 15:02:43 +09:00 committed by Kevin Lange
parent c9ca86bece
commit 792c5dc0e9
2 changed files with 34 additions and 89 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

119
boot.s
View File

@ -1,7 +1,4 @@
[bits 16]
jmp main
;jmp protected_start
main:
mov ax, 0x0000
mov ds, ax
@ -10,65 +7,17 @@ main:
cli
mov si, msg_hello
call print
; memory scan
mov di, 0x0
call do_e820
jc .e820_failed
; success
mov si, msg_done
call print
mov si, msg_a20
call print
jc hang
; a20
in al, 0x92
or al, 2
out 0x92, al
mov si, msg_done
call print
mov si, msg_gdt
call print
call set_gdt
mov si, msg_done
call print
mov eax, cr0
or eax, 1
mov cr0, eax
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp far 0x08:(protected_start)
; failure
.e820_failed:
mov si, msg_fail
call print
jmp hang
hang:
jmp hang
print: lodsb
or al, al
jz .ch_done
mov ah, 0x0E
int 0x10
jmp print
.ch_done:
ret
set_gdt:
; basic flat GDT
xor eax, eax
mov ax, ds
shl eax, 4
@ -78,7 +27,26 @@ set_gdt:
sub eax, gdt_base
mov [gdtr], ax
lgdt [gdtr]
ret
; protected mode enable flag
mov eax, cr0
or eax, 1
mov cr0, eax
; set segments
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
; jump to protected mode entry
extern kmain
jmp far 0x08:(kmain)
hang:
jmp hang
do_e820:
xor ebx, ebx ; ebx must be 0 to start
@ -125,42 +93,25 @@ do_e820:
stc ; "function unsupported" error exit
ret
db '--- Data Starts Here ---'
msg_hello db 'Scanning memory... ', 0
msg_gdt db 'Instaling gdt... ', 0
msg_a20 db 'Flipping A20... ', 0
msg_done db 'Done', 13, 10, 0
msg_fail db 'Failed', 13, 10, 0
;typedef struct {
; /* Limits */
; uint16_t limit_low;
; /* Segment address */
; uint16_t base_low;
; uint8_t base_middle;
; /* Access modes */
; uint8_t access;
; uint8_t granularity;
; uint8_t base_high;
align 8
; GDT pointer
gdtr
dw 0
dd 0
; GDT (null, code, data)
gdt_base
; null
dq 0
; code
dw 0xFFFF
dw 0
db 0
db 0x9a
db 0xcf
db 0
; data
dw 0xffff
dw 0
db 0
@ -169,15 +120,7 @@ gdt_base
db 0
gdt_end
; memory map entry count
global mmap_ent
mmap_ent db 0, 0
[bits 32]
align 8
protected_start:
mov eax, 0xAAAABBBB
mov [0xB8000], eax
;jmp protected_start
extern kmain
jmp (kmain)

4
cstuff.c
View File

@ -41,6 +41,8 @@ static void clear() {
int kmain() {
clear();
print("ToaruOS-NIH Bootloader v0.1\n");
print("ToaruOS-NIH Bootloader v0.1\n\n");
print("Doing stuff.\n");
while (1);
}