1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build (386 || arm) && (freebsd || linux || netbsd || windows)
5
6package purego
7
8// CDecl marks a function as being called using the __cdecl calling convention as defined in
9// the [MSDocs] when passed to NewCallback. It must be the first argument to the function.
10// This is only useful on 386 Windows, but it is safe to use on other platforms.
11//
12// [MSDocs]: https://learn.microsoft.com/en-us/cpp/cpp/cdecl?view=msvc-170
13type CDecl struct{}
14
15const (
16 maxArgs = 32
17)
18
19type syscall15Args struct {
20 fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr
21 a16, a17, a18, a19, a20, a21, a22, a23, a24, a25, a26, a27, a28, a29, a30, a31, a32 uintptr
22 f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12, f13, f14, f15, f16 uintptr
23 arm64_r8 uintptr
24}
25
26func (s *syscall15Args) Set(fn uintptr, ints []uintptr, floats []uintptr, r8 uintptr) {
27 s.fn = fn
28 s.a1 = ints[0]
29 s.a2 = ints[1]
30 s.a3 = ints[2]
31 s.a4 = ints[3]
32 s.a5 = ints[4]
33 s.a6 = ints[5]
34 s.a7 = ints[6]
35 s.a8 = ints[7]
36 s.a9 = ints[8]
37 s.a10 = ints[9]
38 s.a11 = ints[10]
39 s.a12 = ints[11]
40 s.a13 = ints[12]
41 s.a14 = ints[13]
42 s.a15 = ints[14]
43 s.a16 = ints[15]
44 s.a17 = ints[16]
45 s.a18 = ints[17]
46 s.a19 = ints[18]
47 s.a20 = ints[19]
48 s.a21 = ints[20]
49 s.a22 = ints[21]
50 s.a23 = ints[22]
51 s.a24 = ints[23]
52 s.a25 = ints[24]
53 s.a26 = ints[25]
54 s.a27 = ints[26]
55 s.a28 = ints[27]
56 s.a29 = ints[28]
57 s.a30 = ints[29]
58 s.a31 = ints[30]
59 s.a32 = ints[31]
60 s.f1 = floats[0]
61 s.f2 = floats[1]
62 s.f3 = floats[2]
63 s.f4 = floats[3]
64 s.f5 = floats[4]
65 s.f6 = floats[5]
66 s.f7 = floats[6]
67 s.f8 = floats[7]
68 s.f9 = floats[8]
69 s.f10 = floats[9]
70 s.f11 = floats[10]
71 s.f12 = floats[11]
72 s.f13 = floats[12]
73 s.f14 = floats[13]
74 s.f15 = floats[14]
75 s.f16 = floats[15]
76 s.arm64_r8 = r8
77}
78
79// SyscallN takes fn, a C function pointer and a list of arguments as uintptr.
80// There is an internal maximum number of arguments that SyscallN can take. It panics
81// when the maximum is exceeded. It returns the result and the libc error code if there is one.
82//
83// In order to call this function properly make sure to follow all the rules specified in [unsafe.Pointer]
84// especially point 4.
85//
86// NOTE: SyscallN does not properly call functions that have both integer and float parameters.
87// See discussion comment https://github.com/ebiten/purego/pull/1#issuecomment-1128057607
88// for an explanation of why that is.
89//
90// On amd64, if there are more than 8 floats the 9th and so on will be placed incorrectly on the
91// stack.
92//
93// The pragma go:nosplit is not needed at this function declaration because it uses go:uintptrescapes
94// which forces all the objects that the uintptrs point to onto the heap where a stack split won't affect
95// their memory location.
96//
97//go:uintptrescapes
98func SyscallN(fn uintptr, args ...uintptr) (r1, r2, err uintptr) {
99 if fn == 0 {
100 panic("purego: fn is nil")
101 }
102 if len(args) > maxArgs {
103 panic("purego: too many arguments to SyscallN")
104 }
105 // add padding so there is no out-of-bounds slicing
106 var tmp [maxArgs]uintptr
107 copy(tmp[:], args)
108 return syscall_syscall15X(fn, tmp[0], tmp[1], tmp[2], tmp[3], tmp[4], tmp[5], tmp[6], tmp[7], tmp[8], tmp[9], tmp[10], tmp[11], tmp[12], tmp[13], tmp[14])
109}