diff options
Diffstat (limited to 'src/entry.asm')
| -rw-r--r-- | src/entry.asm | 134 |
1 files changed, 126 insertions, 8 deletions
diff --git a/src/entry.asm b/src/entry.asm index d17246d..855c50f 100644 --- a/src/entry.asm +++ b/src/entry.asm @@ -6,6 +6,11 @@ %define LOCATION 0x7c00 ; Bootloader location +; General configurations +%define VIDEO_WIDTH 1024 +%define VIDEO_HEIGHT 768 +%define VIDEO_BPP 3 + ; Interrupts %define VIDEO_INT 0x10 ; Video BIOS Interrupt %define DISK_INT 0x13 ; Disk BIOS Interrupt @@ -16,7 +21,7 @@ %define RETURN 0x0D ; Return character (\r) %define NULL 0x00 ; NULL character (\0) -; Video commands +; Video commands (VGA) %define VIDEO_CLEAR 0x03 ; Clear screen command %define VIDEO_OUT 0x0e ; Teletype output command @@ -40,11 +45,28 @@ %define EXT2_SIG 0xef53 ; Signature ; MMAP constants -%define MMAP_START 0x400 ; Starts at 0x400, ends at 0x500 +%define MMAP_START 0x400 ; Struct starts at 0x400, ends at 0x500 %define MMAP_SIZE 0x18 ; Struct size %define MMAP_SIG 0x0534d4150 ; Signature ("SMAP") %define MMAP_BIOS_MAGIC 0xe820 ; BIOS int 15h code to get address map +; Video constants (VESA) +%define VESA_START 0x2000 ; Struct starts at 0x2000 +%define VESA_END 0x3000 ; Struct ends at 0x3000 +%define VESA_GET_MODES 0x4f00 ; Get video modes (via 10h) +%define VESA_GET_INFO 0x4f01 ; Get video mode info (via 10h) +%define VESA_SET_MODE 0x4f02 ; Set video mode (via 10h) +%define VESA_SUCCESS_SIG 0x004f ; Returns if VBE call succeeded +%define VESA_MODE_OFFSET 0xe ; Offset to mode pointer +%define VESA_MODE_SEGMENT 0x10 ; Mode pointer segment +%define VESA_LIST_END 0xffff ; End of mode list +%define VESA_PITCH_OFFSET 0x10 ; Pitch offset in mode info +%define VESA_WIDTH_OFFSET 0x12 ; Width offset in mode info +%define VESA_HEIGHT_OFFSET 0x14 ; Height offset in mode info +%define VESA_BPP_OFFSET 0x19 ; Bytes Per Pixel (BPP) offset in mode info +%define VESA_FRAMEBUFFER_OFFSET 0x2a ; Framebuffer offset in mode info +%define VESA_LFB_FLAG 0x4000 ; Enable LFB flag + ; A20 constants %define A20_GATE 0x92 ; Fast A20 gate %define A20_ENABLED 0b10 ; Bit 1 defines whether A20 is enabled @@ -56,7 +78,8 @@ %define GDT_DESCRIPTOR 0b00010000 ; Descriptor type, set for code/data %define GDT_EXECUTABLE 0b00001000 ; Can be executed %define GDT_READWRITE 0b00000010 ; Read/write access for code/data -%define GDT_GRANULARITY (0xc0 | 0x0f) ; Use paged 32 granularity +%define GDT_GRANULARITY (0xc0 | 0x0f) ; Use paged 32 bit granularity +%define GDT_DATA_OFFSET 0x10 ; Offset to GDT data segment ; Kernel constants %define STACK_POINTER 0x00900000 ; The initial stack pointer in kernel mode @@ -134,6 +157,88 @@ lba_error: call print jmp $ +; Now put some data and routines just before the end of the boot sector because +; we've still got some space left :) + +; Video map routine +video_map: + xor eax, eax + mov es, ax + mov bx, VESA_START ; Set load address + mov di, bx + mov ax, VESA_GET_MODES ; Get video modes + int VIDEO_INT ; Ask BIOS for data! + + cmp ax, VESA_SUCCESS_SIG ; Check VBE support in response + jne .error ; Not supported :( + + mov si, [bx + VESA_MODE_OFFSET] ; Mode pointer offset + mov ax, [bx + VESA_MODE_SEGMENT] ; Mode pointer segment + mov es, ax + + mov di, VESA_END ; End of VBE struct +.loop: + mov bx, [es:si] ; Load bx with video mode + cmp bx, VESA_LIST_END ; Is this the end? + jae .done ; Yes, there aren't any modes left + + add si, 2 + mov [.mode], bx + + mov ax, VESA_GET_INFO ; Get mode information + mov cx, [.mode] ; Save in here + int VIDEO_INT ; BIOS interrupt! + cmp ax, VESA_SUCCESS_SIG ; Check if call succeeded + jne .error ; Nope, jump to error! + + xor ax, ax + mov ax, [es:di + VESA_FRAMEBUFFER_OFFSET] ; Save framebuffer + mov [.framebuffer], ax ; Move fb address to struct + + mov ax, [es:di + VESA_PITCH_OFFSET] ; Save pitch + mov bx, [es:di + VESA_WIDTH_OFFSET] ; Save width + mov cx, [es:di + VESA_HEIGHT_OFFSET] ; Save height + mov dx, [es:di + VESA_BPP_OFFSET] ; Save BPP + + mov [.bpp], dx ; Move bpp to struct (bigger bpp is always desired) + add di, 0x100 + + cmp ax, [.pitch] ; Compare with desired pitch + jne .loop ; Not equal, continue search! + cmp bx, [.width] ; Compare with desired height + jne .loop ; Not equal, continue search! + cmp cx, [.height] ; Compare with desired height + jne .loop ; Not equal, continue search! + + lea ax, [es:di - 0x100] + mov [vid_info.array], ax +.set_mode: + mov si, video_success_msg + call print + + xor ax, ax + mov ax, VESA_SET_MODE ; Set VBE mode + mov bx, [.mode] ; Set mode address + mov [vid_info], bx ; Move mode information to array + or bx, VESA_LFB_FLAG ; Enable LFB + int VIDEO_INT ; SET! + cmp ax, VESA_SUCCESS_SIG ; Check if set succeeded + jne .error ; Nope, jump to error! +.done: + ret ; Finished loop and set! +.error: ; Something failed - print message and loop! + mov si, video_error_msg + call print + jmp $ + +; Video default data +.mode dw 0 +.width dw VIDEO_WIDTH +.height dw VIDEO_HEIGHT +.pitch dw (VIDEO_WIDTH * VIDEO_BPP) +.bpp dw VIDEO_BPP +.framebuffer dd 0 + ; Variables hello_msg db "Welcome! Loading Melvix...", NEWLINE, RETURN, NULL disk_error_msg db "Disk error!", NEWLINE, RETURN, NULL @@ -141,9 +246,16 @@ lba_error_msg db "LBA error!", NEWLINE, RETURN, NULL stage_two_msg db "Stage2 loaded", NEWLINE, RETURN, NULL disk_success_msg db "Disk is valid", NEWLINE, RETURN, NULL inode_table_msg db "Found inode table", NEWLINE, RETURN, NULL +video_success_msg db "Found video mode", NEWLINE, RETURN, NULL +video_error_msg db "Video error", NEWLINE, RETURN, NULL protected_msg db "Jumping to protected mode", NEWLINE, RETURN, NULL drive db 0 +; Video info struct +vid_info: +.mode dd 0 ; Mode info pointer +.array dd 0 ; Mode array pointer + ; Data packet: db 0x10 ; Packet size @@ -199,6 +311,9 @@ stage_two: mov [dest], bx call kernel_load + ; Set video mode + call video_map + ; Load mmap xor eax, eax mov es, eax @@ -240,7 +355,7 @@ memory_map: jne short .fail ; Result wasn't correct signature test ebx, ebx ; Is size >1 je short .fail ; Nope, worthless :( - jmp short .loop + jmp short .loop ; Loop! .next: mov eax, MMAP_BIOS_MAGIC ; Re-move because 0x15 clears or sth mov [es:di + 20], dword 1 ; Force a valid ACPI entry @@ -307,7 +422,7 @@ protected_mode: pop ecx ; Start of memory map mov [mem_info], ecx ; Starting boundary of struct - mov ax, 10h ; Set data segement indentifier + mov ax, GDT_DATA_OFFSET ; Data segment offset of GDT mov ds, ax mov es, ax mov fs, ax @@ -316,7 +431,10 @@ protected_mode: mov esp, STACK_POINTER ; Move stack pointer - mov eax, mem_info ; Pass meminfo to kernel + mov eax, vid_info ; Pass VBE struct to kernel + push eax ; Push as second kernel parameter + + mov eax, mem_info ; Pass mmap to kernel push eax ; Push as first kernel parameter mov edx, KERNEL_POSITION @@ -335,14 +453,14 @@ gdt: ; GDTs start gdt_null: ; Must be null dd 0 dd 0 -gdt_code: ; Code section +gdt_code: ; Code segment dw GDT_MAX_LIMIT ; Limit dw 0 ; First base db 0 ; Second base db (GDT_PRESENT | GDT_DESCRIPTOR | GDT_EXECUTABLE | GDT_READWRITE) ; Configuration db GDT_GRANULARITY ; Granularity db 0 ; Third base -gdt_data: ; Data section +gdt_data: ; Data segment dw GDT_MAX_LIMIT ; Limit dw 0 ; First base db 0 ; Second base |