text: /****************************************************************************
   * arch/or1k/src/mor1kx/up_initialstate.c
   *
   *   Copyright (C) 2018 Extent3D. All rights reserved.
   *   Author: Matt Thompson <matt@extent3d.com>
   *
   * 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 <arch/spr.h>
  
  /****************************************************************************
   * 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 sr;
  
    /* Initialize the idle thread stack */
  
    if (tcb->pid == 0)
      {
        up_use_stack(tcb, (void *)(g_idle_topstack -
          CONFIG_IDLETHREAD_STACKSIZE), CONFIG_IDLETHREAD_STACKSIZE);
      }
  
    /* Initialize the initial exception register context structure */
  
    memset(xcp, 0, sizeof(struct xcptcontext));
  
    xcp->regs[REG_R1]      = (uint32_t)tcb->adj_stack_ptr;
    xcp->regs[REG_PC]      = (uint32_t)tcb->start;
  
    mfspr(SPR_SYS_SR, sr);
    xcp->regs[REG_SR]      = sr;
  
  #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
  
  #ifdef 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
  
    /* Enable or disable interrupts, based on user configuration */
  
  #ifdef CONFIG_SUPPRESS_INTERRUPTS
    xcp->regs[REG_PRIMASK] = 1;
  #endif /* CONFIG_SUPPRESS_INTERRUPTS */
  }
  