136 lines
4.3 KiB
C++
136 lines
4.3 KiB
C++
// Low-level functions for atomic operations: m68k version -*- C++ -*-
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// Copyright (C) 2001-2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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#include <ext/atomicity.h>
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namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#if ( defined(__mc68020__) || defined(__mc68030__) \
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|| defined(__mc68040__) || defined(__mc68060__) ) \
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&& !defined(__mcpu32__)
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// These variants support compare-and-swap.
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_Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
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{
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register _Atomic_word __result = *__mem;
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register _Atomic_word __temp;
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__asm__ __volatile__ ("1: move%.l %0,%1\n\t"
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"add%.l %3,%1\n\t"
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"cas%.l %0,%1,%2\n\t"
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"jne 1b"
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: "=d" (__result), "=&d" (__temp), "=m" (*__mem)
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: "d" (__val), "0" (__result), "m" (*__mem));
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return __result;
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}
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#elif defined(__rtems__)
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// This code is only provided for reference. RTEMS uses now the atomic
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// builtins and libatomic. See configure.host.
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//
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// TAS/JBNE is unsafe on systems with strict priority-based scheduling.
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// Disable interrupts, which we can do only from supervisor mode.
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_Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
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{
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_Atomic_word __result;
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short __level, __tmpsr;
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__asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr"
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: "=d"(__level), "=d"(__tmpsr) : "1"(0x700));
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__result = *__mem;
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*__mem = __result + __val;
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__asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level));
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return __result;
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}
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#else
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template<int __inst>
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struct _Atomicity_lock
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{
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static volatile unsigned char _S_atomicity_lock;
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};
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template<int __inst>
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volatile unsigned char _Atomicity_lock<__inst>::_S_atomicity_lock = 0;
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template volatile unsigned char _Atomicity_lock<0>::_S_atomicity_lock;
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_Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
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{
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_Atomic_word __result;
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// bset with no immediate addressing (not SMP-safe)
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#if defined(__mcfisaa__) || defined(__mcfisaaplus__)
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__asm__ __volatile__("1: bset.b #7,%0@\n\tjbne 1b"
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: /* no outputs */
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: "a"(&_Atomicity_lock<0>::_S_atomicity_lock)
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: "cc", "memory");
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// CPU32 and CF ISAs B & C support test-and-set (SMP-safe).
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#elif defined(__mcpu32__) || defined(__mcfisab__) || defined (__mcfisac__)
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__asm__ __volatile__("1: tas %0\n\tjbne 1b"
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: "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
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: /* none */
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: "cc");
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// Use bset with immediate addressing for 68000/68010 (not SMP-safe)
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// NOTE: TAS is available on the 68000, but unsupported by some Amiga
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// memory controllers.
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#else
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__asm__ __volatile__("1: bset.b #7,%0\n\tjbne 1b"
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: "+m"(_Atomicity_lock<0>::_S_atomicity_lock)
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: /* none */
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: "cc");
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#endif
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__result = *__mem;
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*__mem = __result + __val;
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_Atomicity_lock<0>::_S_atomicity_lock = 0;
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return __result;
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}
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#endif /* TAS / BSET */
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void
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__attribute__ ((__unused__))
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__atomic_add(volatile _Atomic_word* __mem, int __val) throw ()
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{
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// Careful: using add.l with a memory destination is not
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// architecturally guaranteed to be atomic.
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__exchange_and_add(__mem, __val);
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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