5 files changed, 214 insertions, 0 deletions

diff --git a/src/kernel/boot.asm b/src/kernel/boot.asm
index 198625a..4dccebb 100644
--- a/src/kernel/boot.asm
+++ b/src/kernel/boot.asm
@@ -44,6 +44,8 @@ stublet:
 
 %include "src/kernel/apm/apm.asm"
 
+%include "src/kernel/graphics/vesa.asm"
+
 ; Store the stack
 SECTION .bss
     resb 8192 ; Reserve 8KiB
diff --git a/src/kernel/graphics/graphics.h b/src/kernel/graphics/graphics.h
index a9ed917..1f36d48 100644
--- a/src/kernel/graphics/graphics.h
+++ b/src/kernel/graphics/graphics.h
@@ -18,4 +18,7 @@ void terminal_put_char(char c);
 
 void terminal_write_line(const char *data);
 
+// VESA
+void vesa_init();
+
 #endif
\ No newline at end of file
diff --git a/src/kernel/graphics/vesa.asm b/src/kernel/graphics/vesa.asm
new file mode 100644
index 0000000..9d8e231
--- /dev/null
+++ b/src/kernel/graphics/vesa.asm
@@ -0,0 +1,201 @@
+global find_mode
+global best_video_mode
+
+vbe_info_block:
+	.signature					db "VBE2"	; indicate support for VBE 2.0+
+	.version					dw 0
+	.oem						dd 0
+	.capabilities 				dd 0
+	.video_modes				dd 0
+	.video_memory				dw 0
+	.software_rev				dw 0
+	.vendor						dd 0
+	.product_name				dd 0
+	.product_rev				dd 0
+	.reserved					times 222 db 0
+	.oem_data					times 256 db 0
+
+mode_info_block:
+	.attributes					dw 0
+	.window_a					db 0
+	.window_b					db 0
+	.granularity				dw 0
+	.window_size				dw 0
+	.segment_a					dw 0
+	.segment_b					dw 0
+	.win_func_ptr			 	dd 0
+	.pitch						dw 0
+	.width						dw 0
+	.height						dw 0
+	.w_char						db 0
+	.y_char						db 0
+	.planes						db 0
+	.bpp						db 0
+	.banks						db 0
+	.memory_model				db 0
+	.bank_size					db 0
+	.image_pages				db 0
+	.reserved0					db 0
+
+	.red_mask					db 0
+	.red_position				db 0
+	.green_mask					db 0
+	.green_position				db 0
+	.blue_mask					db 0
+	.blue_position				db 0
+	.reserved_mask				db 0
+	.reserved_position			db 0
+	.direct_color_attributes	db 0
+
+	.framebuffer				dd 0
+	.off_screen_mem_off			dd 0
+	.off_screen_mem_size		dw 0
+	.reserved1					times 206 db 0
+
+best_video_mode:
+	.bpp db 0
+	.height dw 0
+	.width dw 0
+	.mode dw 0
+	.framebuffer dd 0
+	.bytes_per_line dw 0
+	.bytes_per_pixel dd 0
+	.x_cur_max dw 0
+	.y_cur_max dw 0
+
+segments dw 0
+offset  dw 0
+mode 	dw 0
+
+width equ 1024
+height equ 768
+bpp equ 32
+
+search_video_mode:
+    [bits 16]
+
+    push es
+    mov ax, 0x4F00
+    mov di, vbe_info_block
+    int 0x10
+    pop es
+
+    mov ax, word [vbe_info_block.video_modes]
+    mov [offset], ax
+    mov ax, word [vbe_info_block.video_modes+2]
+    mov [segments], ax
+
+    mov ax, [segments]
+    mov fs, ax
+    mov si, [offset]
+
+    mov cx, 1
+    push cx
+
+find_mode:
+	mov dx, [fs:si]
+	add si, 2
+	mov [offset], si
+	mov [mode], dx
+	mov ax, 0
+	mov fs, ax
+
+	push es
+	mov ax, 0x4F01
+	mov cx, [mode]
+	mov di, mode_info_block
+	int 0x10
+	pop es
+
+	cmp ax, 0x004F
+
+	pop cx
+	cmp cx, 4
+	je reset_counter
+	inc cx
+	push cx
+
+	check_mode:
+		mov cx, 0
+		mov bx, [best_video_mode.width]
+		cmp bx, [mode_info_block.width]
+		jl save_and_continue
+		je compare_height
+		jmp next_mode
+
+	compare_height:
+		mov bx, [best_video_mode.height]
+		cmp bx, [mode_info_block.height]
+		jl save_and_continue
+		je compare_bpp
+		jmp next_mode
+
+	compare_bpp:
+		mov dx, [best_video_mode.bpp]
+		mov ax, [mode_info_block.bpp]
+		and ax, 11111111b
+		cmp dx, ax
+		jl save_and_continue
+		jmp next_mode
+
+	save_and_continue:
+		mov bx, [mode_info_block.width]
+		mov [best_video_mode.width], bx
+
+		shr bx,3
+		dec bx
+		mov [best_video_mode.x_cur_max], bx
+
+		mov bx, [mode_info_block.height]
+		mov [best_video_mode.height], bx
+
+		shr bx, 4
+		dec bx
+		mov word [best_video_mode.y_cur_max], ax
+
+		mov ebx, 0
+		mov bl, [mode_info_block.bpp]
+		mov byte [best_video_mode.bpp], bl
+		shr ebx, 3
+		mov dword [best_video_mode.bytes_per_pixel], ebx
+
+
+		mov bx, [mode]
+		mov [best_video_mode.mode], bx
+		mov ebx, [mode_info_block.framebuffer]
+		mov dword[best_video_mode.framebuffer], ebx
+		mov bx, [mode_info_block.pitch]
+		mov word [best_video_mode.bytes_per_line],bx
+		jmp next_mode
+
+pop es
+
+jmp $
+
+new_line_and_next_mode:
+	mov cx,1
+	push cx
+	jmp next_mode
+
+reset_counter:
+	mov cx, 1
+	push cx
+	jmp check_mode
+
+set_mode:
+	push es
+	mov ax, 0x4F02
+	mov bx, [best_video_mode.mode]
+	or bx, 0x4000
+	mov di, 0
+	int 0x10
+	pop es
+
+	cmp ax, 0x4F
+	clc
+
+next_mode:
+	mov ax, [segments]
+	mov fs, ax
+	mov si, [offset]
+	jmp find_mode
diff --git a/src/kernel/graphics/vesa.c b/src/kernel/graphics/vesa.c
new file mode 100644
index 0000000..b178645
--- /dev/null
+++ b/src/kernel/graphics/vesa.c
@@ -0,0 +1,7 @@
+#include "graphics.h"
+
+extern char *find_mode();
+
+void vesa_init() {
+    terminal_write_line(find_mode());
+}
\ No newline at end of file
diff --git a/src/kernel/kernel.c b/src/kernel/kernel.c
index 49fe0b7..fb180ae 100644
--- a/src/kernel/kernel.c
+++ b/src/kernel/kernel.c
@@ -14,6 +14,7 @@ void kernel_main(void) {
     __asm__ __volatile__ ("sti");
 
     terminal_initialize();
+    vesa_init();
     terminal_write_string("Melvix loaded successfully!\n");
 
     timer_install();