Feat: Keyboard strokes working and in buffer

boot/kernel.asm

@@ -2,14 +2,79 @@
 ; Assembly entry point for the kernel
 [bits 64]
 [extern kmain]      ; kmain is defined in kernel.c
+[extern __keyboard_handle_scancode]
+[extern __bss_start]
+[extern __bss_end]
 
 global _start       ; Make _start visible to linker
 
 _start:
+    call fill_idt
+
+; IMPORTANT
+    ; Zero out the .bss section
+    cld
+    mov rdi, __bss_start
+    mov rcx, __bss_end
+    sub rcx, rdi
+    xor rax, rax
+    rep stosb
+
     ; We're already in 64-bit mode with stack set up
     ; Just call the C kernel
+    sti
     call kmain
     
     ; If kmain returns, hang
     jmp $
+    hlt
 
+
+; Set up a minimal IDT
+fill_idt:
+    ; Fill IDT with different handlers for different exceptions
+    mov rdi, 0x4210         ; IDT location
+    mov rax, keyboard_handler
+
+    mov word [rdi], ax              ; Offset low
+    mov word [rdi + 2], 0x18        ; Code segment
+    mov byte [rdi + 4], 0           ; IST
+    mov byte [rdi + 5], 0x8E        ; Present, interrupt gate
+    shr rax, 16
+    mov word [rdi + 6], ax          ; Offset middle
+    shr rax, 16
+    mov dword [rdi + 8], eax        ; Offset high
+    mov dword [rdi + 12], 0         ; Reserved
+    ret
+
+; keyboard handler - Catch PIC interrupt
+keyboard_handler:
+    push rax
+    push rdx
+    push rdi
+    push rcx
+    push rsi
+    push r8
+    push r9
+    push r10
+    push r11
+
+    mov dx, 0x60
+    in al, dx
+
+    mov dil, al
+    call __keyboard_handle_scancode
+
+    mov al, 0x20
+    out 0x20, al
+
+    pop r11
+    pop r10
+    pop r9
+    pop r8
+    pop rsi
+    pop rcx
+    pop rdi
+    pop rdx
+    pop rax
+    iretq