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/****************************************************************************
* arch/arm/src/armv7-m/up_initialstate.c
*
* Copyright (C) 2009, 2011-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <stdint.h>
#include <string.h>
#include <nuttx/arch.h>
#include "up_internal.h"
#include "up_arch.h"
#include "psr.h"
#include "exc_return.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_initial_state
*
* Description:
* A new thread is being started and a new TCB
* has been created. This function is called to initialize
* the processor specific portions of the new TCB.
*
* This function must setup the intial architecture registers
* and/or stack so that execution will begin at tcb->start
* on the next context switch.
*
****************************************************************************/
void up_initial_state(struct tcb_s *tcb)
{
struct xcptcontext *xcp = &tcb->xcp;
/* Initialize the initial exception register context structure */
memset(xcp, 0, sizeof(struct xcptcontext));
/* Save the initial stack pointer */
xcp->regs[REG_SP] = (uint32_t)tcb->adj_stack_ptr;
#ifdef CONFIG_ARMV7M_STACKCHECK
/* Set the stack limit value */
xcp->regs[REG_R10] = (uint32_t)tcb->stack_alloc_ptr + 64;
/* Fill the stack with a watermark value */
memset(tcb->stack_alloc_ptr, 0xff, tcb->adj_stack_size);
#endif
/* Save the task entry point (stripping off the thumb bit) */
xcp->regs[REG_PC] = (uint32_t)tcb->start & ~1;
/* Specify thumb mode */
xcp->regs[REG_XPSR] = ARMV7M_XPSR_T;
/* If this task is running PIC, then set the PIC base register to the
* address of the allocated D-Space region.
*/
#ifdef CONFIG_PIC
if (tcb->dspace != NULL)
{
/* Set the PIC base register (probably R10) to the address of the
* alloacated D-Space region.
*/
xcp->regs[REG_PIC] = (uint32_t)tcb->dspace->region;
}
#ifdef CONFIG_NXFLAT
/* Make certain that bit 0 is set in the main entry address. This
* is only an issue when NXFLAT is enabled. NXFLAT doesn't know
* anything about thumb; the addresses that NXFLAT sets are based
* on file header info and won't have bit 0 set.
*/
tcb->entry.main = (main_t)((uint32_t)tcb->entry.main | 1);
#endif
#endif /* CONFIG_PIC */
#if defined(CONFIG_ARMV7M_CMNVECTOR) || defined(CONFIG_BUILD_PROTECTED)
/* All tasks start via a stub function in kernel space. So all
* tasks must start in privileged thread mode. If CONFIG_BUILD_PROTECTED
* is defined, then that stub function will switch to unprivileged
* mode before transferring control to the user task.
*/
xcp->regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
#endif /* CONFIG_ARMV7M_CMNVECTOR || CONFIG_BUILD_PROTECTED */
#if defined(CONFIG_ARMV7M_CMNVECTOR) && defined(CONFIG_ARCH_FPU)
xcp->regs[REG_FPSCR] = 0; // XXX initial FPSCR should be configurable
xcp->regs[REG_FPReserved] = 0;
#endif /* CONFIG_ARMV7M_CMNVECTOR && CONFIG_ARCH_FPU */
/* Enable or disable interrupts, based on user configuration */
#ifdef CONFIG_SUPPRESS_INTERRUPTS
#ifdef CONFIG_ARMV7M_USEBASEPRI
xcp->regs[REG_BASEPRI] = NVIC_SYSH_DISABLE_PRIORITY;
#else
xcp->regs[REG_PRIMASK] = 1;
#endif
#else /* CONFIG_SUPPRESS_INTERRUPTS */
#ifdef CONFIG_ARMV7M_USEBASEPRI
xcp->regs[REG_BASEPRI] = NVIC_SYSH_PRIORITY_MIN;
#endif
#endif /* CONFIG_SUPPRESS_INTERRUPTS */
}
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