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/************************************************************************************
* arch/arm/src/armv7-m/up_saveusercontext.S
*
* Copyright (C) 2009, 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
************************************************************************************/
/************************************************************************************
* Included Files
************************************************************************************/
#include <nuttx/config.h>
#include <arch/irq.h>
#include "nvic.h"
#include "svcall.h"
/************************************************************************************
* Pre-processor Definitions
************************************************************************************/
/************************************************************************************
* Global Symbols
************************************************************************************/
.syntax unified
.thumb
.file "up_saveusercontext.S"
/************************************************************************************
* Macros
************************************************************************************/
/************************************************************************************
* Public Functions
************************************************************************************/
/************************************************************************************
* Name: up_saveusercontext
*
* Description:
* Save the current thread context. Full prototype is:
*
* int up_saveusercontext(uint32_t *saveregs);
*
* Return:
* 0: Normal return
* 1: Context switch return
*
************************************************************************************/
.text
.thumb_func
.globl up_saveusercontext
.type up_saveusercontext, function
up_saveusercontext:
/* Perform the System call with R0=0 and R1=regs */
mov r1, r0 /* R1: regs */
mov r0, #SYS_save_context /* R0: save context (also return value) */
svc 0 /* Force synchronous SVCall (or Hard Fault) */
/* There are two return conditions. On the first return, R0 (the
* return value will be zero. On the second return we need to
* force R0 to be 1.
*/
add r2, r1, #(4*REG_R0)
mov r3, #1
str r3, [r2, #0]
bx lr /* "normal" return with r0=0 or
* context switch with r0=1 */
.size up_saveusercontext, .-up_saveusercontext
.end
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