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Diffstat (limited to 'libstdc++-v3/config/cpu/m68k/bits/atomicity.h')
| -rw-r--r-- | libstdc++-v3/config/cpu/m68k/bits/atomicity.h | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/libstdc++-v3/config/cpu/m68k/bits/atomicity.h b/libstdc++-v3/config/cpu/m68k/bits/atomicity.h new file mode 100644 index 00000000000..c5d339469e3 --- /dev/null +++ b/libstdc++-v3/config/cpu/m68k/bits/atomicity.h @@ -0,0 +1,158 @@ +// Low-level functions for atomic operations: m68k version -*- C++ -*- + +// Copyright (C) 2001, 2002 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 2, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING. If not, write to the Free +// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, +// USA. + +// As a special exception, you may use this file as part of a free software +// library without restriction. Specifically, if other files instantiate +// templates or use macros or inline functions from this file, or you compile +// this file and link it with other files to produce an executable, this +// file does not by itself cause the resulting executable to be covered by +// the GNU General Public License. This exception does not however +// invalidate any other reasons why the executable file might be covered by +// the GNU General Public License. + +#ifndef _BITS_ATOMICITY_H +#define _BITS_ATOMICITY_H 1 + +typedef int _Atomic_word; + +#if defined(__mc68020__) || defined(__mc68030__) \ + || defined(__mc68040__) || defined(__mc68060__) +// These variants support compare-and-swap. + +static inline _Atomic_word +__attribute__ ((__unused__)) +__exchange_and_add (volatile _Atomic_word *__mem, int __val) +{ + register _Atomic_word __result = *__mem; + register _Atomic_word __temp; + __asm__ __volatile__ ("1: move%.l %0,%1\n\t" + "add%.l %2,%1\n\t" + "cas%.l %0,%1,%3\n\t" + "jbne 1b" + : "=d" (__result), "=&d" (__temp) + : "d" (__val), "m" (*__mem), "0" (__result) + : "memory"); + return __result; +} + +#elif defined(__rtems__) + /* + * TAS/JBNE is unsafe on systems with strict priority-based scheduling. + * Disable interrupts, which we can do only from supervisor mode. + */ +static inline _Atomic_word +__attribute__ ((__unused__)) +__exchange_and_add (volatile _Atomic_word *__mem, int __val) +{ + _Atomic_word __result; + short __level, __tmpsr; + __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr" + : "=d"(__level), "=d"(__tmpsr) : "1"(0x700)); + + __result = *__mem; + *__mem = __result + __val; + + __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level)); + + return __result; +} + +#elif !defined(__mcf5200__) && !defined(__mcf5300__) +// 68000, 68010, cpu32 and 5400 support test-and-set. + +template <int __inst> +struct __Atomicity_lock +{ + static volatile unsigned char _S_atomicity_lock; +}; + +template <int __inst> +volatile unsigned char __Atomicity_lock<__inst>::_S_atomicity_lock = 0; + +template volatile unsigned char __Atomicity_lock<0>::_S_atomicity_lock; + +static inline _Atomic_word +__attribute__ ((__unused__)) +__exchange_and_add (volatile _Atomic_word *__mem, int __val) +{ + _Atomic_word __result; + + __asm__ __volatile__("1: tas %0\n\tjbne 1b" + : "=m"(__Atomicity_lock<0>::_S_atomicity_lock) + : "m"(__Atomicity_lock<0>::_S_atomicity_lock)); + + __result = *__mem; + *__mem = __result + __val; + + __Atomicity_lock<0>::_S_atomicity_lock = 0; + + return __result; +} + +#elif defined(__vxWorks__) || defined(__embedded__) +// The best we can hope for is to disable interrupts, which we +// can only do from supervisor mode. + +static inline _Atomic_word +__attribute__ ((__unused__)) +__exchange_and_add (volatile _Atomic_word *__mem, int __val) +{ + _Atomic_word __result; + short __level, __tmpsr; + __asm__ __volatile__ ("move%.w %%sr,%0\n\tor%.l %0,%1\n\tmove%.w %1,%%sr" + : "=d"(__level), "=d"(__tmpsr) : "1"(0x700)); + + __result = *__mem; + *__mem = __result + __val; + + __asm__ __volatile__ ("move%.w %0,%%sr" : : "d"(__level)); + + return __result; +} + +#else +// These variants do not support any atomic operations at all. + +#warning "__exchange_and_add is not atomic for this target" + +static inline _Atomic_word +__attribute__ ((__unused__)) +__exchange_and_add (volatile _Atomic_word *__mem, int __val) +{ + _Atomic_word __result; + + __result = *__mem; + *__mem = __result + __val; + + return __result; +} + +#endif /* CAS / IRQ / TAS */ + +static inline void +__attribute__ ((__unused__)) +__atomic_add (volatile _Atomic_word* __mem, int __val) +{ + // Careful: using add.l with a memory destination is not + // architecturally guaranteed to be atomic. + (void) __exchange_and_add (__mem, __val); +} + +#endif /* atomicity.h */ |