mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
046c7ebd4a
- Introduce fast spinlock API - Double rand64() perf w/ spinlock - Improve raise() on New Technology - Support gettid() across platforms - Implement SA_NODEFER on New Technology - Move the lock intrinsics into LIBC_INTRIN - Make SIGTRAP recoverable on New Technology - Block SIGCHLD in wait4() on New Technology - Add threading prototypes for XNU and FreeBSD - Rewrite abort() fixing its minor bugs on XNU/NT - Shave down a lot of the content in libc/bits/bits.h - Let signal handlers modify CPU registers on New Technology
54 lines
2.9 KiB
C
54 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 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/intrin/atomic_store.h"
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/**
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* Saves scalar to memory w/ one operation.
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*
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* This is guaranteed to happen in either one or zero operations,
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* depending on whether or not it's possible for *(MEM) to be read
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* afterwards. This macro only forbids compiler from using >1 ops.
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*
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* @param MEM is alignas(𝑘) uint𝑘_t[hasatleast 1] where 𝑘 ∈ {8,16,32,64}
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* @param VAL is uint𝑘_t w/ better encoding for immediates (constexpr)
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* @return VAL
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* @note alignas(𝑘) on nexgen32e only needed for end of page gotcha
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* @note alignas(𝑘) is implied if compiler knows type
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* @note needed to defeat store tearing optimizations
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* @see Intel Six-Thousand Page Manual Manual V.3A §8.2.3.1
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* @see atomic_load()
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*/
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intptr_t(atomic_store)(void *p, intptr_t x, size_t n) {
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switch (n) {
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case 1:
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__builtin_memcpy(p, &x, 1);
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return x;
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case 2:
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__builtin_memcpy(p, &x, 2);
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return x;
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case 4:
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__builtin_memcpy(p, &x, 4);
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return x;
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case 8:
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__builtin_memcpy(p, &x, 8);
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return x;
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default:
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return 0;
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}
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}
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