xiuos/Ubiquitous/Nuttx/nuttx/arch/arm/src/armv8-m/arm_switchcontext.S

82 lines
2.9 KiB
ArmAsm

/****************************************************************************
* arch/arm/src/armv8-m/arm_switchcontext.S
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <arch/irq.h>
#include "nvic.h"
#include "svcall.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Symbols
****************************************************************************/
.syntax unified
.thumb
.file "arm_switchcontext.S"
/****************************************************************************
* Macros
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: arm_switchcontext
*
* Description:
* Save the current thread context and restore the specified context.
* Full prototype is:
*
* void arm_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
*
* Returned Value:
* None
*
****************************************************************************/
.thumb_func
.globl arm_switchcontext
.type arm_switchcontext, function
arm_switchcontext:
/* Perform the System call with R0=1, R1=saveregs, R2=restoreregs */
mov r2, r1 /* R2: restoreregs */
mov r1, r0 /* R1: saveregs */
mov r0, #SYS_switch_context /* R0: context switch */
svc #SYS_syscall /* Force synchronous SVCall (or Hard Fault) */
/* We will get here only after the rerturn from the context switch */
bx lr
.size arm_switchcontext, .-arm_switchcontext
.end