1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5#include "textflag.h"
6
7// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
8// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
9// Use a local trampoline, to avoid taking the address of a dynamically exported
10// function.
11TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
12	MOVL	_crosscall2_ptr(SB), AX
13	MOVL	$crosscall2_trampoline<>(SB), BX
14	MOVL	BX, (AX)
15	RET
16
17TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
18	JMP	crosscall2(SB)
19
20// Called by C code generated by cmd/cgo.
21// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
22// Saves C callee-saved registers and calls cgocallback with three arguments.
23// fn is the PC of a func(a unsafe.Pointer) function.
24TEXT crosscall2(SB),NOSPLIT,$28-16
25	MOVL BP, 24(SP)
26	MOVL BX, 20(SP)
27	MOVL SI, 16(SP)
28	MOVL DI, 12(SP)
29
30	MOVL	ctxt+12(FP), AX
31	MOVL	AX, 8(SP)
32	MOVL	a+4(FP), AX
33	MOVL	AX, 4(SP)
34	MOVL	fn+0(FP), AX
35	MOVL	AX, 0(SP)
36	CALL	runtime·cgocallback(SB)
37
38	MOVL 12(SP), DI
39	MOVL 16(SP), SI
40	MOVL 20(SP), BX
41	MOVL 24(SP), BP
42	RET
43