// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "textflag.h"
#include "abi_arm64.h"

// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
// Use a local trampoline, to avoid taking the address of a dynamically exported
// function.
TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
	MOVD	_crosscall2_ptr(SB), R1
	MOVD	$crosscall2_trampoline<>(SB), R2
	MOVD	R2, (R1)
	RET

TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
	JMP	crosscall2(SB)

// Called by C code generated by cmd/cgo.
// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
// Saves C callee-saved registers and calls cgocallback with three arguments.
// fn is the PC of a func(a unsafe.Pointer) function.
TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
	/*
	 * We still need to save all callee save register as before, and then
	 *  push 3 args for fn (R0, R1, R3), skipping R2.
	 * Also note that at procedure entry in gc world, 8(RSP) will be the
	 *  first arg.
	 */
	SUB	$(8*24), RSP
	STP	(R0, R1), (8*1)(RSP)
	MOVD	R3, (8*3)(RSP)

	SAVE_R19_TO_R28(8*4)
	SAVE_F8_TO_F15(8*14)
	STP	(R29, R30), (8*22)(RSP)


	// Initialize Go ABI environment
	BL	runtime·load_g(SB)
	BL	runtime·cgocallback(SB)

	RESTORE_R19_TO_R28(8*4)
	RESTORE_F8_TO_F15(8*14)
	LDP	(8*22)(RSP), (R29, R30)

	ADD	$(8*24), RSP
	RET