95 lines
3.3 KiB
ArmAsm
95 lines
3.3 KiB
ArmAsm
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/****************************************************************************
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* arch/arm64/src/common/arm64_testset.S
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <arch/spinlock.h>
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#include "arch/syscall.h"
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#include "arm64_macro.inc"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Public Symbols
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****************************************************************************/
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.file "arm64_testset.S"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_testset
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*
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* Description:
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* Perform an atomic test and set operation on the provided spinlock.
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*
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* This function must be provided via the architecture-specific logic.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object.
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*
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* Returned Value:
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* The spinlock is always locked upon return. The previous value of the
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* spinlock variable is returned, either SP_LOCKED if the spinlock was
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* previously locked (meaning that the test-and-set operation failed to
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* obtain the lock) or SP_UNLOCKED if the spinlock was previously unlocked
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* (meaning that we successfully obtained the lock).
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*
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****************************************************************************/
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GTEXT(up_testset)
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SECTION_FUNC(text, up_testset)
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up_testset:
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mov x1, #SP_LOCKED
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/* Test if the spinlock is locked or not */
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1:
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ldaxr x2, [x0] /* Test if spinlock is locked or not */
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cmp x2, x1 /* Already locked? */
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beq 2f /* If already locked, return SP_LOCKED */
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/* Not locked ... attempt to lock it */
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stxr w2, x1, [x0] /* Attempt to set the locked state */
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cbnz w2, 1b /* w2 will be 1 is stxr failed */
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/* Lock acquired -- return SP_UNLOCKED */
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mov x0, #SP_UNLOCKED
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ret
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/* Lock not acquired -- return SP_LOCKED */
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2:
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mov x0, #SP_LOCKED
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ret
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