diff options
| -rw-r--r-- | boot.asm | 90 |
1 files changed, 12 insertions, 78 deletions
@@ -4,26 +4,17 @@ jmp start CR equ 0Dh LF equ 0Ah -K_CS_ADDR equ 07E0h +K_CS_ADDR equ 0080h start: mov ax, 07c0h mov ds, ax ; set data segment mov ax, 07e0h mov ss, ax ; set stack segment - mov sp, 2000h ; 8192k - - push bp ; set up stack frame - mov bp, sp - sub sp, 2 ; local storage + mov sp, 0200h ; 512 byte stack mov [drive0], dl ; save first detected drive - call cls ; clear screen - - push 0 ; - call setcursor ; set cursor position - push banner ; call puts ; print version add sp, 2 ; clean up @@ -32,15 +23,16 @@ start: call disk_reset add sp, 2 - xor cx, cx - mov ax, K_CS_ADDR - mov es, ax - push msg_loading call puts add sp, 2 - mov bx, 0 + ; begin disk operations + xor cx, cx + mov ax, K_CS_ADDR + mov es, ax + + mov bx, 0000h ; starting address (es:bx) mov di, 2 ; start at sector .loader: mov al, 1 ; read one sector @@ -53,34 +45,22 @@ start: call putc add sp, 2 - add bx, 200h ; increment address by 512 bytes + add bx, 0200h ; increment address by 512 bytes inc di ; increment sector read count - cmp di, 16 ; 8K (i'll make this smarter later) + cmp di, 20h ; 16K (512 * 32) jle .loader ; keep reading push msg_done call puts add sp, 2 - add sp, 2 ; remove local storage - mov sp, bp - pop bp - mov dx, [drive0] ; the kernel will need the boot drive number - - ;cli ; disable interrupts - ;mov ax, K_CS_ADDR ; get code segment - ;mov ds, ax ; set data segment - ;mov es, ax ; set extra segment - ;mov ax, 0800h - ;mov ss, ax ; set stack segment - ;mov sp, 0ffffh ; set stack pointer (~64k) - jmp K_CS_ADDR:0000h ; jump to kernel address cli ; disable interrupts jmp $ ; hang + panic: ; Hang system with supplied error message push bp @@ -100,12 +80,8 @@ panic: disk_reset: - push bp - mov bp, sp - pusha - mov ah, 00h ; reset disk - mov dl, [bp + 4] ; disk number + ; dl is drive number int 13h ; BIOS disk service jnc .success @@ -113,9 +89,6 @@ disk_reset: call panic .success: - popa - mov sp, bp - pop bp ret @@ -157,42 +130,6 @@ disk_read: ret -cls: - push bp - mov bp, sp - pusha - - mov ah, 07h ; BIOS - scroll down - mov al, 00h ; lines to scroll (0 == entire screen) - mov bx, 0700h ; color white/black - ; & video page zero - mov cx, 0 - mov dh, 24 ; rows - mov dl, 79 ; cols - int 10h ; BIOS video service - popa - - mov sp, bp - pop bp - ret - - -setcursor: - push bp - mov bp, sp - pusha - - mov ah, 02h ; BIOS - set cursor position - mov bh, 0 ; video page zero - mov dx, [bp + 4] ; address of new cursor value - int 10h ; BIOS video service - - popa - mov sp, bp - pop bp - ret - - putc: ; Write single character at cursor position push bp @@ -233,7 +170,6 @@ puts: ret - ; data drive0: dw 0 banner: db "MINOS Bootloader", CR, LF, 0 @@ -241,8 +177,6 @@ banner: db "MINOS Bootloader", CR, LF, 0 ; General messages msg_loading: db "Loading", 0 msg_done: db "done!", CR, LF, 0 -msg_disk_reset: db "Drive reset successful.", CR, LF, 0 -msg_disk_read: db "Sector read successful.", CR, LF, 0 ; Error messages error_msg_panic: db "PANIC: ", 0 |