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#include "abi_amd64.h"
7
8// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
9// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
10// Use a local trampoline, to avoid taking the address of a dynamically exported
11// function.
12TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
13 MOVQ _crosscall2_ptr(SB), AX
14 MOVQ $crosscall2_trampoline<>(SB), BX
15 MOVQ BX, (AX)
16 RET
17
18TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
19 JMP crosscall2(SB)
20
21// Called by C code generated by cmd/cgo.
22// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
23// Saves C callee-saved registers and calls cgocallback with three arguments.
24// fn is the PC of a func(a unsafe.Pointer) function.
25// This signature is known to SWIG, so we can't change it.
26TEXT crosscall2(SB),NOSPLIT,$0-0
27 PUSH_REGS_HOST_TO_ABI0()
28
29 // Make room for arguments to cgocallback.
30 ADJSP $0x18
31#ifndef GOOS_windows
32 MOVQ DI, 0x0(SP) /* fn */
33 MOVQ SI, 0x8(SP) /* arg */
34 // Skip n in DX.
35 MOVQ CX, 0x10(SP) /* ctxt */
36#else
37 MOVQ CX, 0x0(SP) /* fn */
38 MOVQ DX, 0x8(SP) /* arg */
39 // Skip n in R8.
40 MOVQ R9, 0x10(SP) /* ctxt */
41#endif
42
43 CALL runtime·cgocallback(SB)
44
45 ADJSP $-0x18
46 POP_REGS_HOST_TO_ABI0()
47 RET
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