1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build !386 && !arm && (darwin || 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 = 15
17)
18
19type syscall15Args struct {
20 fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr
21 f1, f2, f3, f4, f5, f6, f7, f8 uintptr
22 arm64_r8 uintptr
23}
24
25func (s *syscall15Args) Set(fn uintptr, ints []uintptr, floats []uintptr, r8 uintptr) {
26 s.fn = fn
27 s.a1 = ints[0]
28 s.a2 = ints[1]
29 s.a3 = ints[2]
30 s.a4 = ints[3]
31 s.a5 = ints[4]
32 s.a6 = ints[5]
33 s.a7 = ints[6]
34 s.a8 = ints[7]
35 s.a9 = ints[8]
36 s.a10 = ints[9]
37 s.a11 = ints[10]
38 s.a12 = ints[11]
39 s.a13 = ints[12]
40 s.a14 = ints[13]
41 s.a15 = ints[14]
42 s.f1 = floats[0]
43 s.f2 = floats[1]
44 s.f3 = floats[2]
45 s.f4 = floats[3]
46 s.f5 = floats[4]
47 s.f6 = floats[5]
48 s.f7 = floats[6]
49 s.f8 = floats[7]
50 s.arm64_r8 = r8
51}
52
53// SyscallN takes fn, a C function pointer and a list of arguments as uintptr.
54// There is an internal maximum number of arguments that SyscallN can take. It panics
55// when the maximum is exceeded. It returns the result and the libc error code if there is one.
56//
57// In order to call this function properly make sure to follow all the rules specified in [unsafe.Pointer]
58// especially point 4.
59//
60// NOTE: SyscallN does not properly call functions that have both integer and float parameters.
61// See discussion comment https://github.com/ebiten/purego/pull/1#issuecomment-1128057607
62// for an explanation of why that is.
63//
64// On amd64, if there are more than 8 floats the 9th and so on will be placed incorrectly on the
65// stack.
66//
67// The pragma go:nosplit is not needed at this function declaration because it uses go:uintptrescapes
68// which forces all the objects that the uintptrs point to onto the heap where a stack split won't affect
69// their memory location.
70//
71//go:uintptrescapes
72func SyscallN(fn uintptr, args ...uintptr) (r1, r2, err uintptr) {
73 if fn == 0 {
74 panic("purego: fn is nil")
75 }
76 if len(args) > maxArgs {
77 panic("purego: too many arguments to SyscallN")
78 }
79 // add padding so there is no out-of-bounds slicing
80 var tmp [maxArgs]uintptr
81 copy(tmp[:], args)
82 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])
83}