text: /****************************************************************************
   *  arch/arm/src/arm/arm_initialstate.c
   *
   *   Copyright (C) 2007-2009, 2011 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 <stdint.h>
  #include <string.h>
  
  #include <nuttx/arch.h>
  
  #include "arm.h"
  #include "arm_internal.h"
  #include "arm_arch.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 initial 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;
    uint32_t cpsr;
  
    /* 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;
  
    /* Save the task entry point */
  
    xcp->regs[REG_PC]      = (uint32_t)tcb->start;
  
    /* 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;
      }
  #endif
  
    /* Set supervisor- or user-mode, depending on how NuttX is configured and
     * what kind of thread is being started.  Disable FIQs in any event
     */
  
  #ifdef CONFIG_BUILD_KERNEL
    if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_KERNEL)
      {
        /* It is a kernel thread.. set supervisor mode */
  
        cpsr               = SVC_MODE | PSR_F_BIT;
      }
    else
      {
        /* It is a normal task or a pthread.  Set user mode */
  
        cpsr               = USR_MODE | PSR_F_BIT;
      }
  #else
    /* If the kernel build is not selected, then all threads run in
     * supervisor-mode.
     */
  
    cpsr                   = SVC_MODE | PSR_F_BIT;
  #endif
  
    /* Enable or disable interrupts, based on user configuration */
  
  # ifdef CONFIG_SUPPRESS_INTERRUPTS
    cpsr                  |= PSR_I_BIT;
  # endif
  
    xcp->regs[REG_CPSR]    = cpsr;
  }
  