.section .shared

.global _isr_stubs
_isr_stubs:
.set i, 0
.rept 256
	.set _stub_start, .

	cli
	.if i !=  8 && i != 10 && i != 11 && i != 12 && i != 13 && i != 14 && i != 17 && i != 21 && i != 29 && i != 30
		/* no error code was pushed - push anything, just to line up the stack */
		push %rbx
	.endif
	call _isr_stage2

	.if . - _stub_start > 8
		.error "isr stubs over maximum size"
		.abort
	.endif
	.align 8, 0xCC
	.set i, i + 1
.endr

_isr_stage2:
	/* UserRegs */
	/* I'm skipping fields that are in the IRET stack frame
	 * on the assumption it's easier to deal with them from C. */
	push $0 /* flags */
	push $0 /* ip */

	push %rax
	push %rcx
	push %rdx
	push %rbx

	push $0 /* rsp */
	push %rbp
	push %rsi
	push %rdi

	push %r8
	push %r9
	push %r10
	push %r11

	push %r12
	push %r13
	push %r14
	push %r15
	// TODO FXSAVE might be required on interrupts too?
	// on interrupts - no
	// on syscalls - yes
	// have fun figuring that one out
	// basically if you're context switching, FXSAVE

	/* first argument: vector nr. computed from the return address at offset
	 * 18*8 = 144 */
	mov 144(%rsp), %rdi
	sub $_isr_stubs, %rdi
	shr $3, %rdi

	/* second argument: stack frame */
	mov %rsp, %rsi

	/* load kernel paging */
	mov %cr3, %rbx
	push %rbx
	mov $pml4_identity, %rbx
	mov %rbx, %cr3

	mov %rsp, %rbp
	mov $_isr_big_stack, %rsp
	call isr_stage3

	mov %rbp, %rsp
	pop %rax /* restore old cr3 */
	mov %rax, %cr3

	/* restore registers */
	pop %r15
	pop %r14
	pop %r13
	pop %r12

	pop %r11
	pop %r10
	pop %r9
	pop %r8

	pop %rdi
	pop %rsi
	pop %rbp
	pop %rbx /* skip rsp */

	pop %rbx
	pop %rdx
	pop %rcx
	pop %rax

	/* skips:
	 *  UserRegs.ip
	 *  UserRegs.flags
	 *  return address from the CALL in the stub
	 *  error code */
	add $32, %rsp
	iretq

.align 8
// TODO stack overflow check
.skip 256 // seems to be enough
.global _isr_mini_stack
_isr_mini_stack: