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kernel/roska.fasm

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format binary
use32
org 0x100000
MB_HEADER_MAGIC equ 0x1BADB002
MB_PAGE_ALIGN equ (1 shl 0)
MB_MEMORY_INFO equ (1 shl 1)
MB_VIDEO_REQUEST equ (1 shl 2)
MB_AOUT_KLUDGE equ (1 shl 16)
MB_HEADER_FLAGS equ MB_PAGE_ALIGN or MB_MEMORY_INFO or MB_VIDEO_REQUEST
MB_HEADER_FLAGS equ MB_PAGE_ALIGN or MB_MEMORY_INFO or MB_VIDEO_REQUEST or MB_AOUT_KLUDGE
MB_CHECKSUM equ -(MB_HEADER_MAGIC + MB_HEADER_FLAGS)
;; safe modes according to https://wiki.osdev.org/VESA_Video_Modes
VWIDTH equ 80 ; 640/720
VHEIGHT equ 25 ; 480
VDEPTH equ 0 ; 24/32, zero in textmode
multiboot:
dd MB_HEADER_MAGIC
dd MB_HEADER_FLAGS
dd MB_CHECKSUM
dd multiboot ; header address
dd 0x100000 ; load address
dd bss_start ; load end address
dd bss_end ; bss end address
dd start ; entry address
dd 1 ; video mode_type (0:fb, 1:txt) (set flags[2]!)
dd VWIDTH ; video width
dd VHEIGHT ; video height
dd VDEPTH ; video depth
start:
; Setup stack
mov ebp, stack_top
mov esp, stack_top
;push ebx ; mboot info struct addr
;push eax ; 0x2BADB002
mov [mbootmagic], eax
;mov [mbootaddr], ebx
call con_disable_cursor
call conclear
mov esi, msg.roskainiting
call conwriteln
hang:
;cli
.loop:
;hlt
jmp .loop
;give character in AL
conputchar:
mov ah, [txtbuf.col]
mov dx, ax
; dx has the whole character cell now
xor eax, eax
mov al, [txtbuf.y]
mov bl, 80
mul bl
movzx bx, [txtbuf.x]
add ax, bx
add ax, ax
add eax, 0xb8000
mov [eax], dx
cmp bl, 79
je connewline
inc bl
mov [txtbuf.x], bl
ret
conwriteln:
lodsb
cmp al, 0
je connewline
call conputchar
jmp conwriteln
connewline:
mov [txtbuf.x], 0
mov al, [txtbuf.y]
cmp al, 24
je conscroll
inc al
mov [txtbuf.y], al
ret
conscroll:
ret
conclear:
mov ecx, 80*25
mov edi, 0xb8000
mov ah, 0x07
mov al, 0
rep stosw
mov [txtbuf.col], ah
mov [txtbuf.x], 0
mov [txtbuf.y], 0
ret
con_disable_cursor:
mov dx, 0x3D4
mov al, 0xA ; low cursor shape register
out dx, al
inc dx
mov al, 0x20 ; bits 6-7 unused, bit 5 disables the cursor, bits 0-4 control the cursor shape
out dx, al
ret
mbootaddr: dd 0
mbootmagic: dd 0
txtbuf:
.x db 0
.y db 0
.col db 0x07 ;gray on black
fb:
.addr dd 0
.pitch dd 0
.width dd 0
.height dd 0
.depth db 0
.bytespp db 0
.rpos db 0
;.rmasksize db 0
.gpos db 0
;.gmasksize db 0
.bpos db 0
;.bmasksize db 0
msg:
.roskainiting db "rOSka initializing...", 0
align 4096
bss_start:
align 4096
stack_bottom:
rb 16384
stack_top:
bss_end: