Bootloader do some directory restructuring

bootloader/bios/framebuffer.S

@@ -0,0 +1,156 @@
+.set TARGET_WIDTH,	800
+.set TARGET_HEIGHT,	600
+.set TARGET_BPP,	32
+
+.code16
+.section .stage2
+
+# Find suitable video mode
+# return:
+#	ax: video mode number if found, 0 otherwise
+.global vesa_find_video_mode
+vesa_find_video_mode:
+	pushw %ax
+	pushw %cx
+	pushw %di
+	pushl %esi
+
+	# clear target mode and frame buffer
+	movw $0, (vesa_target_mode)
+	movl $0, (framebuffer + 0)
+	movl $0, (framebuffer + 4)
+	movl $0, (framebuffer + 8)
+	movl $0, (framebuffer + 12)
+	movw $0, (framebuffer + 16)
+
+	# get vesa information
+	movw $0x4F00, %ax
+	movw $vesa_info_buffer, %di
+	int $0x10
+	cmpb $0x4F, %al; jne .vesa_unsupported
+	cmpb $0x00, %ah; jne .vesa_error
+
+	# confirm that response starts with 'VESA'
+	cmpl $0x41534556, (vesa_info_buffer)
+	jne .vesa_error
+
+	# confirm that version is atleast 2.0
+	cmpw $0x0200, (vesa_info_buffer + 0x04)
+	jb .vesa_unsupported_version
+
+	movl $(vesa_info_buffer + 0x0E), %esi
+	movl (%esi), %esi
+ .vesa_find_video_mode_loop_modes:
+	cmpw $0xFFFF, (%esi)
+	je .vesa_find_video_mode_loop_modes_done
+
+	# get info of next mode
+	movw $0x4F01, %ax
+	movw (%esi), %cx
+	movw $vesa_mode_info_buffer, %di
+	int $0x10
+	cmpb $0x4F, %al; jne .vesa_unsupported
+	cmpb $0x00, %ah; jne .vesa_error
+
+	# check whether in graphics mode
+	testb $0x10, (vesa_mode_info_buffer + 0)
+	jz .vesa_find_video_mode_next_mode
+
+	# compare mode's dimensions
+	cmpw $TARGET_WIDTH, (vesa_mode_info_buffer + 0x12)
+	jne .vesa_find_video_mode_next_mode
+	cmpw $TARGET_HEIGHT, (vesa_mode_info_buffer + 0x14)
+	jne .vesa_find_video_mode_next_mode
+	cmpb $TARGET_BPP, (vesa_mode_info_buffer + 0x19)
+	jne .vesa_find_video_mode_next_mode
+
+	movl (vesa_mode_info_buffer + 0x28), %esi
+	movl %esi,				(framebuffer + 0)
+	movw (vesa_mode_info_buffer + 0x10), %ax
+	movw %ax,				(framebuffer + 4)
+	movl $TARGET_WIDTH,		(framebuffer + 8)
+	movl $TARGET_HEIGHT,	(framebuffer + 12)
+	movb $TARGET_BPP,		(framebuffer + 16)
+	movb $1,				(framebuffer + 17)
+
+	movw %cx, (vesa_target_mode)
+	jmp .vesa_find_video_mode_loop_modes_done
+
+ .vesa_find_video_mode_next_mode:
+	addl $2, %esi
+	jmp .vesa_find_video_mode_loop_modes
+
+ .vesa_find_video_mode_loop_modes_done:
+	popl %esi
+	popw %di
+	popw %cx
+	popw %ax
+	ret
+
+ .vesa_unsupported:
+	movw $vesa_unsupported_msg, %si
+	jmp print_and_halt
+ .vesa_unsupported_version:
+	movw $vesa_unsupported_version_msg, %si
+	jmp print_and_halt
+ .vesa_error:
+	movw $vesa_error_msg, %si
+	jmp print_and_halt
+
+
+# set mode found from vesa_find_video_mode. if no mode
+# was found, set it to 80x25 text mode to clear the screen.
+.global vesa_set_target_mode
+vesa_set_target_mode:
+	pushw %ax
+	pushw %bx
+
+	movw (vesa_target_mode), %bx
+	testw %bx, %bx
+	jz .vesa_set_target_mode_generic	
+
+	movw $0x4F02, %ax
+	orw $0x4000, %bx
+	int $0x10
+
+	jmp .set_video_done
+
+ .vesa_set_target_mode_generic:
+	movb $0x03, %al
+	movb $0x00, %ah
+	int $0x10
+
+ .set_video_done:
+	popw %bx
+	popw %ax
+	ret
+
+
+vesa_error_msg:
+	.asciz "VESA error"
+vesa_unsupported_msg:
+	.asciz "VESA unsupported"
+vesa_unsupported_version_msg:
+	.asciz "VESA unsupported version"
+vesa_success_msg:
+	.asciz "VESA success"
+
+.section .bss
+
+vesa_info_buffer:
+	.skip 512
+
+vesa_mode_info_buffer:
+	.skip 256
+
+vesa_target_mode:
+	.skip 2
+
+.global framebuffer
+framebuffer:
+	.skip 4	# address
+	.skip 4	# pitch
+	.skip 4	# width
+	.skip 4 # height
+	.skip 1 # bpp
+	.skip 1 # type