GotSSL-Kernel/kernel.asm at main · gotssl95/GotSSL-Kernel · GitHub

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use16
org 0x0000

main:
mov ax, 0x07e0
mov ds, ax
mov es, ax
call cls
call beep
mov si, welcome
call print

shell_loop:
call prompt
call read_input
mov si, input_buffer
call check_command
jmp shell_loop

print:
lodsb
cmp al, 0
je done
mov ah, 0x0E
int 0x10
jmp print
done:
ret

cls:
mov ah, 0x00
mov al, 0x03
int 0x10
ret

prompt:
mov si, prompt_msg
call print
ret

read_input:
mov di, input_buffer
.read_char:
mov ah, 0
int 0x16
cmp al, 0x0D
je .done
cmp al, 0x08
je .backspace
stosb
mov ah, 0x0E
int 0x10
jmp .read_char
.backspace:
cmp di, input_buffer
je .read_char
dec di
mov ah, 0x0E
mov al, 0x08
int 0x10
mov al, ' '
int 0x10
mov al, 0x08
int 0x10
jmp .read_char
.done:
mov al, 0
stosb
mov ah, 0x0E
mov al, 0x0A
int 0x10
mov al, 0x0D
int 0x10
ret

check_command:
mov si, input_buffer
mov di, info_cmd
call str_eq
cmp al, 1
je do_info
mov si, unknown_msg
call print
ret

do_info:
mov si, info_msg
call print
ret

str_eq:
.next_char:
lodsb
cmp al, [di]
jne .not_equal
cmp al, 0
je .equal
inc di
jmp .next_char
.not_equal:
mov al, 0
ret
.equal:
mov al, 1
ret

beep:
mov al, 0b10110110
out 0x43, al
mov ax, 1193
out 0x42, al
mov al, ah
out 0x42, al
in al, 0x61
mov bl, al
or al, 11b
out 0x61, al
mov cx, 0FFFFh
.b1:
nop
loop .b1
mov al, bl
out 0x61, al
ret

welcome: db "GSSLOS v1.0",0x0A,0
prompt_msg: db "[#] ",0
input_buffer: times 32 db 0
info_cmd: db "info",0
info_msg: db "GotSSLOS written in pure ASM by @gotssl. 2025",0x0A,0
unknown_msg: db "Unknown command",0x0A,0