76 lines
2.2 KiB
C++
76 lines
2.2 KiB
C++
/*
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* Copyright (c) 2012, 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* 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 WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* interlock.cpp
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* Functions that perform non-atomic operations in an atomic manner.
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*/
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#include <sortix/kernel/interlock.h>
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#include <sortix/kernel/kernel.h>
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namespace Sortix {
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// TODO: This is likely not the most optimal way to perform these operations.
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// TODO: Just discard this whole thing in favor of __atomic_?
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ilret_t InterlockedModify(unsigned long* ptr,
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ilockfunc f,
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unsigned long user)
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{
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unsigned long old_value, new_value;
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// TODO: Migrate to __atomic.
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do
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{
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old_value = *((volatile unsigned long*) ptr); /* TODO: Need volatile? */
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new_value = f(old_value, user);
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} while ( !__sync_bool_compare_and_swap(ptr, old_value, new_value) );
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ilret_t ret;
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ret.o = old_value;
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ret.n = new_value;
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return ret;
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}
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static unsigned long AddFunction(unsigned long val, unsigned long arg)
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{
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return val + arg;
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}
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static unsigned long SubFunction(unsigned long val, unsigned long arg)
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{
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return val - arg;
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}
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ilret_t InterlockedIncrement(unsigned long* ptr)
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{
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return InterlockedModify(ptr, AddFunction, 1);
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}
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ilret_t InterlockedDecrement(unsigned long* ptr)
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{
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return InterlockedModify(ptr, SubFunction, 1);
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}
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ilret_t InterlockedAdd(unsigned long* ptr, unsigned long arg)
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{
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return InterlockedModify(ptr, AddFunction, arg);
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}
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ilret_t InterlockedSub(unsigned long* ptr, unsigned long arg)
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{
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return InterlockedModify(ptr, SubFunction, arg);
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}
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} // namespace Sortix
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