diff options
Diffstat (limited to 'src/boot.s')
| -rw-r--r-- | src/boot.s | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/src/boot.s b/src/boot.s new file mode 100644 index 0000000..28da384 --- /dev/null +++ b/src/boot.s @@ -0,0 +1,81 @@ + mov ax, 0x7c0 + mov ds, ax + mov ax, 0xb800 ; protected mode video memory segment (addr / 16) + mov es, ax + mov si, msg + + cld + + call print + + cli + +; print using BIOS functions +; print_loop: +; lodsb ; load byte from DS:SI into al +; or al, al +; jz hang +; mov ah, 0x0E +; int 0x10 +; jmp print_loop + +; print without using BIOS functions +print: + lodsb + cmp al, 0 + jz exit_print + + mov ah, 0x0F + mov cx, ax + + movzx bx, byte [xpos] + shl bx, 1 + movzx ax, byte [ypos] + mov dx, 160 + mul dx + + xor di, di + mov di, bx + add di, ax + + mov ax, cx + stosw + add byte[xpos], 1 + jmp print + +exit_print: + add byte[ypos], 1 + mov byte[xpos], 0 + ret + +hang: + jmp hang + + + ; vars + msg db 'Hello world', 13, 10, 0 ; Hello world CR LF \0 + xpos db 0 + ypos db 0 + + + ; fill + times 0x1b8 -($-$$) db 0 ; fill MBR boostrap + dd 0 ; fill unique disk ID + dw 0 ; reserved + ; write first partition table entry CHS for start and end are set to 0 + db 0x80 ; mark the partition as bootable + db 0x0 ; partition start head + dw 0x0 ; partition start sector and cylinder (sector = 1, cylinder = 0) + db 0x06 ; system ID (partition type, 07 = exFAT) + db 0x0 ; partition end head + dw 0x0 ; partition end sector and cylinder (sector = 5, cylinder = 455) + dd 0x1 ; partition start LBA + dd 0x3fff ; partition end LBA + + times 0x10 db 0 ; fill second partition table entry + times 0x10 db 0 ; fill third partition table entry + times 0x10 db 0 ; fill fourth partition table entry + dw 0xAA55 ; valid boot sector signature + + ; db 'TEST' + ; times 0x800000 - ($-$$) db 0 |