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https://github.com/jart/cosmopolitan.git
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59 lines
2.5 KiB
ArmAsm
59 lines
2.5 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 2022 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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// Saves machine to 𝑥 and activates 𝑦, i.e.
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//
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// getcontext(x);
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// setcontext(y);
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//
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// Except using this API is safer and goes 2x faster:
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//
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// swapcontext(x, y);
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//
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// @return 0 on success, or -1 w/ errno
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// @returnstwice
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.ftrace1
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swapcontext:
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.ftrace2
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#include "libc/calls/getcontext.inc"
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#ifdef __x86_64__
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push %rbp
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mov %rsp,%rbp
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push %rsi
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push %rsi
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call __swapcontextsig
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pop %rdi
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pop %rdi
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pop %rbp
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test %eax,%eax
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jnz 1f
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#elif defined(__aarch64__)
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stp x29,x30,[sp,#-32]!
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mov x29,sp
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str x1,[sp,16]
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bl __swapcontextsig
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ldr x1,[sp,16]
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ldp x29,x30,[sp],#32
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cbnz w0,1f
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mov x0,x1
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#endif
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jmp __tailcontext
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1: ret
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.endfn swapcontext,globl
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