isr_handler.asm

section .text

; Defined in isr.c
[extern irq_wrapper_handler]
[extern isr_wrapper_handler]

; Common ISR code
isr_common_stub:
; 1. Save CPU state

; Pushes edi,esi,ebp,ebx,edx,ecx,eax
push eax
push ecx
push edx
push ebx
push ebp
push esi
push edi

mov ax, ds ; Lower 16-bits of eax = ds.
push eax ; save the data segment descriptor
mov ax, 0x10  ; kernel data segment descriptor
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax

; push pointer to interrupt_registers on stack
push esp

; 2. Call C handler
call isr_wrapper_handler

; set new esp
mov esp, eax

; 3. Restore state
pop eax 
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax

pop edi
pop esi
pop ebp
pop ebx
pop edx
pop ecx
pop eax

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

; Common IRQ code. Identical to ISR code except for the 'call' 
; and the 'pop ebx'
irq_common_stub:

; Pushes edi,esi,ebp,ebx,edx,ecx,eax
push eax
push ecx
push edx
push ebx
push ebp
push esi
push edi

mov ax, ds
push eax
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax

; push pointer to interrupt_registers on stack
push esp

call irq_wrapper_handler ; Different than the ISR code

; set new esp
mov esp, eax

pop ebx  ; Different than the ISR code
mov ds, bx
mov es, bx
mov fs, bx
mov gs, bx

pop edi
pop esi
pop ebp
pop ebx
pop edx
pop ecx
pop eax

add esp, 8
;sti
iret 

; We don't get information about which interrupt was caller
; when the handler is run, so we will need to have a different handler
; for every interrupt.
; Furthermore, some interrupts push an error code onto the stack but others
; don't, so we will push a dummy error code for those which don't, so that
; we have a consistent stack for all of them.

; First make the ISRs global
global isr0
global isr1
global isr2
global isr3
global isr4
global isr5
global isr6
global isr7
global isr8
global isr9
global isr10
global isr11
global isr12
global isr13
global isr14
global isr15
global isr16
global isr17
global isr18
global isr19
global isr20
global isr21
global isr22
global isr23
global isr24
global isr25
global isr26
global isr27
global isr28
global isr29
global isr30
global isr31
; IRQs
global irq0
global irq1
global irq2
global irq3
global irq4
global irq5
global irq6
global irq7
global irq8
global irq9
global irq10
global irq11
global irq12
global irq13
global irq14
global irq15

; 0: Divide By Zero Exception
isr0:
push byte 0
push byte 0
jmp isr_common_stub

; 1: Debug Exception
isr1:
push byte 0
push byte 1
jmp isr_common_stub

; 2: Non Maskable Interrupt Exception
isr2:
push byte 0
push byte 2
jmp isr_common_stub

; 3: Int 3 Exception
isr3:
push byte 0
push byte 3
jmp isr_common_stub

; 4: INTO Exception
isr4:
push byte 0
push byte 4
jmp isr_common_stub

; 5: Out of Bounds Exception
isr5:
push byte 0
push byte 5
jmp isr_common_stub

; 6: Invalid Opcode Exception
isr6:
push byte 0
push byte 6
jmp isr_common_stub

; 7: Coprocessor Not Available Exception
isr7:
push byte 0
push byte 7
jmp isr_common_stub

; 8: Double Fault Exception (With Error Code!)
isr8:
push byte 8
jmp isr_common_stub

; 9: Coprocessor Segment Overrun Exception
isr9:
push byte 0
push byte 9
jmp isr_common_stub

; 10: Bad TSS Exception (With Error Code!)
isr10:
push byte 10
jmp isr_common_stub

; 11: Segment Not Present Exception (With Error Code!)
isr11:
push byte 11
jmp isr_common_stub

; 12: Stack Fault Exception (With Error Code!)
isr12:
push byte 12
jmp isr_common_stub

; 13: General Protection Fault Exception (With Error Code!)
isr13:
push byte 13
jmp isr_common_stub

; 14: Page Fault Exception (With Error Code!)
isr14:
push byte 14
jmp isr_common_stub

; 15: Reserved Exception
isr15:
push byte 0
push byte 15
jmp isr_common_stub

; 16: Floating Point Exception
isr16:
push byte 0
push byte 16
jmp isr_common_stub

; 17: Alignment Check Exception
isr17:
push byte 0
push byte 17
jmp isr_common_stub

; 18: Machine Check Exception
isr18:
push byte 0
push byte 18
jmp isr_common_stub

; 19: Reserved
isr19:
push byte 0
push byte 19
jmp isr_common_stub

; 20: Reserved
isr20:
push byte 0
push byte 20
jmp isr_common_stub

; 21: Reserved
isr21:
push byte 0
push byte 21
jmp isr_common_stub

; 22: Reserved
isr22:
push byte 0
push byte 22
jmp isr_common_stub

; 23: Reserved
isr23:
push byte 0
push byte 23
jmp isr_common_stub

; 24: Reserved
isr24:
push byte 0
push byte 24
jmp isr_common_stub

; 25: Reserved
isr25:
push byte 0
push byte 25
jmp isr_common_stub

; 26: Reserved
isr26:
push byte 0
push byte 26
jmp isr_common_stub

; 27: Reserved
isr27:
push byte 0
push byte 27
jmp isr_common_stub

; 28: Reserved
isr28:
push byte 0
push byte 28
jmp isr_common_stub

; 29: Reserved
isr29:
push byte 0
push byte 29
jmp isr_common_stub

; 30: Reserved
isr30:
push byte 0
push byte 30
jmp isr_common_stub

; 31: Reserved
isr31:
push byte 0
push byte 31
jmp isr_common_stub

; IRQ handlers
irq0:
push byte 0
push byte 32
jmp irq_common_stub

irq1:
push byte 0
push byte 33
jmp irq_common_stub

irq2:
push byte 0
push byte 34
jmp irq_common_stub

irq3:
push byte 0
push byte 35
jmp irq_common_stub

irq4:
push byte 0
push byte 36
jmp irq_common_stub

irq5:
push byte 0
push byte 37
jmp irq_common_stub

irq6:
push byte 0
push byte 38
jmp irq_common_stub

irq7:
push byte 0
push byte 39
jmp irq_common_stub

irq8:
push byte 0
push byte 40
jmp irq_common_stub

irq9:
push byte 0
push byte 41
jmp irq_common_stub

irq10:
push byte 0
push byte 42
jmp irq_common_stub

irq11:
push byte 0
push byte 43
jmp irq_common_stub

irq12:
push byte 0
push byte 44
jmp irq_common_stub

irq13:
push byte 0
push byte 45
jmp irq_common_stub

irq14:
push byte 0
push byte 46
jmp irq_common_stub

irq15:
push byte 0
push byte 47
jmp irq_common_stub