syscall.go RawHistoryFolder

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build darwin || windows || linux
5
6package purego
7
8const maxArgs = 9
9
10// SyscallN takes fn, a C function pointer and a list of arguments as uintptr.
11// There is an internal maximum number of arguments that SyscallN can take. It panics
12// when the maximum is exceeded. It returns the result and the libc error code if there is one.
13//
14// NOTE: SyscallN does not properly call functions that have both integer and float parameters.
15// See discussion comment https://github.com/ebiten/purego/pull/1#issuecomment-1128057607
16// for an explanation of why that is.
17//
18// On amd64, if there are more than 8 floats the 9th and so on will be placed incorrectly on the
19// stack.
20//
21// The pragma go:nosplit is not needed at this function declaration because it uses go:uintptrescapes
22// which forces all the objects that the uintptrs point to onto the heap where a stack split won't affect
23// their memory location.
24//
25//go:uintptrescapes
26func SyscallN(fn uintptr, args ...uintptr) (r1, r2, err uintptr) {
27	if fn == 0 {
28		panic("purego: fn is nil")
29	}
30	if len(args) > maxArgs {
31		panic("purego: too many arguments to SyscallN")
32	}
33	// add padding so there is no out-of-bounds slicing
34	var tmp [maxArgs]uintptr
35	copy(tmp[:], args)
36	return syscall_syscall9X(fn, tmp[0], tmp[1], tmp[2], tmp[3], tmp[4], tmp[5], tmp[6], tmp[7], tmp[8])
37}