79 lines
1.6 KiB
C++
79 lines
1.6 KiB
C++
//
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// spinlock.cpp
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//
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// Circle - A C++ bare metal environment for Raspberry Pi
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// Copyright (C) 2015 R. Stange <rsta2@o2online.de>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program 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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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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#include "SpinLock.h"
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#include "defs.h"
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bool SpinLock::s_bEnabled = true;
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SpinLock::SpinLock()
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: m_bLocked(false)
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{
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}
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SpinLock::~SpinLock(void)
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{
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}
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void SpinLock::Acquire(void)
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{
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#ifdef HAS_MULTICORE
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if (s_bEnabled)
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{
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// See: ARMv7-A Architecture Reference Manual, Section D7.3
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asm volatile
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(
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"mov r1, %0\n"
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"mov r2, #1\n"
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"1: ldrex r3, [r1]\n"
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"cmp r3, #0\n"
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"wfene\n"
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"strexeq r3, r2, [r1]\n"
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"cmpeq r3, #0\n"
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"bne 1b\n"
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"dmb\n"
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: : "r" ((u32)&m_bLocked)
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);
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}
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#endif
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}
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void SpinLock::Release(void)
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{
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#ifdef HAS_MULTICORE
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if (s_bEnabled)
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{
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// See: ARMv7-A Architecture Reference Manual, Section D7.3
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asm volatile
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(
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"mov r1, %0\n"
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"mov r2, #0\n"
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"dmb\n"
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"str r2, [r1]\n"
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"dsb\n"
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"sev\n"
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: : "r" ((u32)&m_bLocked)
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);
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}
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#endif
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}
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