text: /****************************************************************************
   * arch/avr/src/avr32/up_stackframe.c
   *
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.  The
   * ASF licenses this file to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the
   * License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations
   * under the License.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <sched.h>
  #include <debug.h>
  
  #include <nuttx/arch.h>
  #include <arch/irq.h>
  
  #include "up_internal.h"
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_stack_frame
   *
   * Description:
   *   Allocate a stack frame in the TCB's stack to hold thread-specific data.
   *   This function may be called anytime after up_create_stack() or
   *   up_use_stack() have been called but before the task has been started.
   *
   *   Thread data may be kept in the stack (instead of in the TCB) if it is
   *   accessed by the user code directly.  This includes such things as
   *   argv[].  The stack memory is guaranteed to be in the same protection
   *   domain as the thread.
   *
   *   The following TCB fields will be re-initialized:
   *
   *   - adj_stack_size: Stack size after removal of the stack frame from
   *     the stack
   *   - stack_base_ptr: Adjusted stack base pointer after the TLS Data and
   *     Arguments has been removed from the stack allocation.
   *
   * Input Parameters:
   *   - tcb:  The TCB of new task
   *   - frame_size:  The size of the stack frame to allocate.
   *
   *  Returned Value:
   *   - A pointer to bottom of the allocated stack frame.  NULL will be
   *     returned on any failures.  The alignment of the returned value is
   *     the same as the alignment of the stack itself.
   *
   ****************************************************************************/
  
  FAR void *up_stack_frame(FAR struct tcb_s *tcb, size_t frame_size)
  {
    FAR void *ret;
  
    /* Align the frame_size */
  
    frame_size = STACK_ALIGN_UP(frame_size);
  
    /* Is there already a stack allocated? Is it big enough? */
  
    if (!tcb->stack_alloc_ptr || tcb->adj_stack_size <= frame_size)
      {
        return NULL;
      }
  
    ret = tcb->stack_base_ptr;
    memset(ret, 0, frame_size);
  
    /* Save the adjusted stack values in the struct tcb_s */
  
    tcb->stack_base_ptr  = (FAR uint8_t *)tcb->stack_base_ptr + frame_size;
    tcb->adj_stack_size -= frame_size;
  
    /* And return the pointer to the allocated region */
  
    return ret;
  }
  