// Copyright 2020 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"

// 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
	MOV	_crosscall2_ptr(SB), X7
	MOV	$crosscall2_trampoline<>(SB), X8
	MOV	X8, (X7)
	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
	/*
	 * Push arguments for fn (X10, X11, X13), along with all callee-save
	 * registers. Note that at procedure entry the first argument is at
	 * 8(X2).
	 */
	ADD	$(-8*29), X2
	MOV	X10, (8*1)(X2) // fn unsafe.Pointer
	MOV	X11, (8*2)(X2) // a unsafe.Pointer
	MOV	X13, (8*3)(X2) // ctxt uintptr
	MOV	X8, (8*4)(X2)
	MOV	X9, (8*5)(X2)
	MOV	X18, (8*6)(X2)
	MOV	X19, (8*7)(X2)
	MOV	X20, (8*8)(X2)
	MOV	X21, (8*9)(X2)
	MOV	X22, (8*10)(X2)
	MOV	X23, (8*11)(X2)
	MOV	X24, (8*12)(X2)
	MOV	X25, (8*13)(X2)
	MOV	X26, (8*14)(X2)
	MOV	g, (8*15)(X2)
	MOV	X1, (8*16)(X2)
	MOVD	F8, (8*17)(X2)
	MOVD	F9, (8*18)(X2)
	MOVD	F18, (8*19)(X2)
	MOVD	F19, (8*20)(X2)
	MOVD	F20, (8*21)(X2)
	MOVD	F21, (8*22)(X2)
	MOVD	F22, (8*23)(X2)
	MOVD	F23, (8*24)(X2)
	MOVD	F24, (8*25)(X2)
	MOVD	F25, (8*26)(X2)
	MOVD	F26, (8*27)(X2)
	MOVD	F27, (8*28)(X2)

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

	MOV	(8*4)(X2), X8
	MOV	(8*5)(X2), X9
	MOV	(8*6)(X2), X18
	MOV	(8*7)(X2), X19
	MOV	(8*8)(X2), X20
	MOV	(8*9)(X2), X21
	MOV	(8*10)(X2), X22
	MOV	(8*11)(X2), X23
	MOV	(8*12)(X2), X24
	MOV	(8*13)(X2), X25
	MOV	(8*14)(X2), X26
	MOV	(8*15)(X2), g
	MOV	(8*16)(X2), X1
	MOVD	(8*17)(X2), F8
	MOVD	(8*18)(X2), F9
	MOVD	(8*19)(X2), F18
	MOVD	(8*20)(X2), F19
	MOVD	(8*21)(X2), F20
	MOVD	(8*22)(X2), F21
	MOVD	(8*23)(X2), F22
	MOVD	(8*24)(X2), F23
	MOVD	(8*25)(X2), F24
	MOVD	(8*26)(X2), F25
	MOVD	(8*27)(X2), F26
	MOVD	(8*28)(X2), F27
	ADD	$(8*29), X2

	RET