syscall.go RawHistoryFolder

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4//go:build darwin || windows
5// +build darwin windows
6
7package purego
8
9const maxArgs = 9
10
11// SyscallN takes fn, a C function pointer and a list of arguments as uintptr.
12// There is an internal maximum number of arguments that SyscallN can take. It panics
13// when the maximum is exceeded. It returns the result and the libc error code if there is one.
14//
15// NOTE: SyscallN does not properly call functions that have both integer and float parameters.
16// See discussion comment https://github.com/ebiten/purego/pull/1#issuecomment-1128057607
17// for an explanation of why that is.
18//
19// On amd64, if there are more than 8 floats the 9th and so on will be placed incorrectly on the
20// stack.
21//
22// The pragma go:nosplit is not needed at this function declaration because it uses go:uintptrescapes
23// which forces all the objects that the uintptrs point to onto the heap where a stack split won't affect
24// their memory location.
25//
26//go:uintptrescapes
27func SyscallN(fn uintptr, args ...uintptr) (r1, r2, err uintptr) {
28	if fn == 0 {
29		panic("purego: fn is nil")
30	}
31	if len(args) > maxArgs {
32		panic("purego: too many arguments to SyscallN")
33	}
34	// add padding so there is no out-of-bounds slicing
35	var tmp [maxArgs]uintptr
36	copy(tmp[:], args)
37	return syscall_syscall9X(fn, tmp[0], tmp[1], tmp[2], tmp[3], tmp[4], tmp[5], tmp[6], tmp[7], tmp[8])
38}