gdt.asm

[GLOBAL flush_gdt]
flush_gdt:
	mov eax, [esp + 4]
	lgdt [eax]

	mov ax, 0x10
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax

	jmp 0x08:flush
flush:
	ret

	[GLOBAL flush_idt]
flush_idt:
	mov eax, [esp + 4]
	lidt [eax]
	ret

 %macro ISR_NOERRCODE 1  ; define a macro, taking one parameter
  [GLOBAL isr%1]        ; %1 accesses the first parameter.
  isr%1:
    cli
    push byte 0
    push byte %1
    jmp isr_common_stub
%endmacro

%macro ISR_ERRCODE 1
  [GLOBAL isr%1]
  isr%1:
    cli
    push byte %1
    jmp isr_common_stub
%endmacro

	
ISR_NOERRCODE 0
ISR_NOERRCODE 1
ISR_NOERRCODE 2
ISR_NOERRCODE 3
ISR_NOERRCODE 4
ISR_NOERRCODE 5
ISR_NOERRCODE 6
ISR_NOERRCODE 7
ISR_ERRCODE   8
ISR_NOERRCODE 9
ISR_ERRCODE   10
ISR_ERRCODE   11
ISR_ERRCODE   12
ISR_ERRCODE   13
ISR_ERRCODE   14
ISR_NOERRCODE 15
ISR_NOERRCODE 16
ISR_NOERRCODE 17
ISR_NOERRCODE 18
ISR_NOERRCODE 19
ISR_NOERRCODE 20
ISR_NOERRCODE 21
ISR_NOERRCODE 22
ISR_NOERRCODE 23
ISR_NOERRCODE 24
ISR_NOERRCODE 25
ISR_NOERRCODE 26
ISR_NOERRCODE 27
ISR_NOERRCODE 28
ISR_NOERRCODE 29
ISR_NOERRCODE 30
ISR_NOERRCODE 31

extern isr_handler

isr_common_stub:
    pusha                    ; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax

    mov ax, ds               ; Lower 16-bits of eax = ds.
    push eax                 ; save the data segment descriptor

    mov ax, 0x10  ; load the kernel data segment descriptor
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax

    call isr_handler

    pop ebx        ; reload the original data segment descriptor
    mov ds, bx
    mov es, bx
    mov fs, bx
    mov gs, bx

    popa                     ; Pops edi,esi,ebp...
    add esp, 8     ; Cleans up the pushed error code and pushed ISR number
    sti
    iret           ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP