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sortix--sortix/sortix/interlock.cpp
2013-12-17 14:30:23 +01:00

78 lines
2.2 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012, 2013.
This file is part of Sortix.
Sortix 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 3 of the License, or (at your option) any later
version.
Sortix 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
Sortix. If not, see <http://www.gnu.org/licenses/>.
interlock.cpp
Functions that perform non-atomic operations in an atomic manner.
*******************************************************************************/
#include <sortix/kernel/platform.h>
#include <sortix/kernel/interlock.h>
namespace Sortix {
// TODO: This is likely not the most optimal way to perform these operations.
ilret_t InterlockedModify(unsigned long* ptr,
ilockfunc f,
unsigned long user)
{
unsigned long old_value, new_value;
do
{
old_value = *((volatile unsigned long*) ptr); /* TODO: Need volatile? */
new_value = f(old_value, user);
} while ( !__sync_bool_compare_and_swap(ptr, old_value, new_value) );
ilret_t ret;
ret.o = old_value;
ret.n = new_value;
return ret;
}
static unsigned long AddFunction(unsigned long val, unsigned long arg)
{
return val + arg;
}
static unsigned long SubFunction(unsigned long val, unsigned long arg)
{
return val - arg;
}
ilret_t InterlockedIncrement(unsigned long* ptr)
{
return InterlockedModify(ptr, AddFunction, 1);
}
ilret_t InterlockedDecrement(unsigned long* ptr)
{
return InterlockedModify(ptr, SubFunction, 1);
}
ilret_t InterlockedAdd(unsigned long* ptr, unsigned long arg)
{
return InterlockedModify(ptr, AddFunction, arg);
}
ilret_t InterlockedSub(unsigned long* ptr, unsigned long arg)
{
return InterlockedModify(ptr, SubFunction, arg);
}
} // namespace Sortix