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394d998315
At least in neovim, `│vi:` is not recognized as a modeline because it has no preceding whitespace. After fixing this, opening a file yields an error because `net` is not an option. (`noet`, however, is.)
52 lines
2.7 KiB
ArmAsm
52 lines
2.7 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│ vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.internal.h"
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// Invokes system call w/ arity of two.
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//
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// This function has three parameters. The first two are for
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// args passed along to the system call. The third's for the
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// the magic number, indicating which system call is called.
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//
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// The returned value follows the Linux kernel convention ie
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// errors are returned as `-errno`, rather than -1 w/ errno.
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//
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// This helper should not be used to do cancelation points.
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__syscall2:
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#ifdef __aarch64__
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mov x8,x2 // syscall number (linux)
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mov x16,x2 // syscall number (xnu)
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mov x9,0 // clear carry flag
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adds x9,x9,0 // clear carry flag
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svc 0
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bcs 1f
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ret
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1: neg x0,x0
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ret
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#elif defined(__x86_64__)
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mov %edx,%eax // arg3 -> syscall number
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clc // linux saves carry flag
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syscall // bsds set carry on errs
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jnc 1f
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neg %rax // normalizes to system v
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1: ret
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#else
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#error "unsupported architecture"
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#endif
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.endfn __syscall2,globl
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