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/****************************************************************************
* arch/arm/src/lm3s/lm3s_pendsv.c
* arch/arm/src/chip/lm3s_pendsv.c
*
* Copyright (C) 2009 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 <sys/types.h>
#include <string.h>
#include <assert.h>
#include <debug.h>
#include <arch/irq.h>
#include "os_internal.h"
#include "lm3s_internal.h"
/****************************************************************************
* Private Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: lm3xs_pendxv
*
* Description:
* This is PendSV exception handler that performs context switching
*
****************************************************************************/
int lm3s_pendsv(int irq, FAR void *context)
{
uint32 *svregs = (uint32*)context;
uint32 *tcbregs = (uint32*)svregs[REG_R1];
DEBUGASSERT(svregs && svregs == current_regs && tcbregs);
/* The PendSV software interrupt is called with R0 = PendSV command and R1 =
* the TCB register save area.
*/
switch (svregs[REG_R0])
{
/* R0=0: This is a save context command. In this case, we simply need
* to copy the svregs to the tdbregs and return.
*/
case 0:
memcpy(tcbregs, svregs, XCPTCONTEXT_SIZE);
break;
/* R1=1: This a restore context command. In this case, we simply need to
* set current_regs to tcbrgs. svregs == current_regs is the normal exception
* turn. By setting current_regs = tcbregs, we force the return through
* the saved context.
*/
case 1:
current_regs = tcbregs;
break;
default:
PANIC(OSERR_INTERNAL);
break;
}
return OK;
}
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