1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4/*
5trampoline for emulating required C functions for cgo in go (see cgo.go)
6(we convert cdecl calling convention to go and vice-versa)
7Since we're called from go and call into C we can cheat a bit with the calling conventions:
8 - in go all the registers are caller saved
9 - in C we have a couple of callee saved registers
10=> we can use BX, R12, R13, R14, R15 instead of the stack
11C Calling convention cdecl used here (we only need integer args):
121. arg: DI
132. arg: SI
143. arg: DX
154. arg: CX
165. arg: R8
176. arg: R9
18We don't need floats with these functions -> AX=0
19return value will be in AX
20*/
21#include "textflag.h"
22#include "go_asm.h"
23
24// these trampolines map the gcc ABI to Go ABI and then calls into the Go equivalent functions.
25
26TEXT x_cgo_init_trampoline(SB), NOSPLIT, $16
27 MOVQ DI, 0(SP)
28 MOVQ SI, 8(SP)
29 CALL ·x_cgo_init(SB)
30 RET
31
32TEXT x_cgo_thread_start_trampoline(SB), NOSPLIT, $8
33 MOVQ DI, 0(SP)
34 CALL ·x_cgo_thread_start(SB)
35 RET
36
37TEXT x_cgo_setenv_trampoline(SB), NOSPLIT, $8
38 MOVQ DI, 0(SP)
39 CALL ·x_cgo_setenv(SB)
40 RET
41
42TEXT x_cgo_unsetenv_trampoline(SB), NOSPLIT, $8
43 MOVQ DI, 0(SP)
44 CALL ·x_cgo_unsetenv(SB)
45 RET
46
47TEXT x_cgo_notify_runtime_init_done_trampoline(SB), NOSPLIT, $0
48 CALL ·x_cgo_notify_runtime_init_done(SB)
49 RET
50
51// func setg_trampoline(setg uintptr, g uintptr)
52TEXT ·setg_trampoline(SB), NOSPLIT, $0-16
53 MOVQ G+8(FP), DI
54 MOVQ setg+0(FP), AX
55 CALL AX
56 RET
57
58TEXT threadentry_trampoline(SB), NOSPLIT, $16
59 MOVQ DI, 0(SP)
60 CALL ·threadentry(SB)
61 MOVQ 8(SP), AX
62 RET
63
64TEXT ·call5(SB), NOSPLIT, $0-56
65 MOVQ fn+0(FP), BX
66 MOVQ a1+8(FP), DI
67 MOVQ a2+16(FP), SI
68 MOVQ a3+24(FP), DX
69 MOVQ a4+32(FP), CX
70 MOVQ a5+40(FP), R8
71 XORL AX, AX
72 CALL BX
73 MOVQ AX, ret+48(FP)
74 RET