/************************************************************
 * up_createstack.c
 *
 *   Copyright (C) 2007 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 Gregory Nutt 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 <nuttx/arch.h>
#include <nuttx/kmalloc.h>
#include "up_internal.h"

/************************************************************
 * Private Definitions
 ************************************************************/

/************************************************************
 * Private Data
 ************************************************************/

/************************************************************
 * Private Funtions
 ************************************************************/

/************************************************************
 * Public Funtions
 ************************************************************/

/************************************************************
 * Name: up_create_stack
 *
 * Description:
 *   Allocate a stack for a new thread and setup
 *   up stack-related information in the TCB.
 *
 *   The following TCB fields must be initialized:
 *   adj_stack_size: Stack size after adjustment for hardware,
 *     processor, etc.  This value is retained only for debug
 *     purposes.
 *   stack_alloc_ptr: Pointer to allocated stack
 *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
 *     initial value of the stack pointer.
 *
 * Inputs:
 *   tcb: The TCB of new task
 *   stack_size: The requested stack size.  At least this much
 *     must be allocated.
 *
 ************************************************************/

STATUS up_create_stack(_TCB *tcb, size_t stack_size)
{
  STATUS ret = ERROR;

  /* Move up to next even word boundary if necessary */

  size_t adj_stack_size = (stack_size + 3) & ~3;
  size_t adj_stack_words = adj_stack_size >> 2;

  /* Allocate the memory for the stack */

  uint32 *stack_alloc_ptr = (uint32*)kmalloc(adj_stack_size);
  if (stack_alloc_ptr)
    {
      /* This is the address of the last word in the allocation */

      size_t *adj_stack_ptr = &stack_alloc_ptr[adj_stack_words - 1];

      /* Save the values in the TCB */

      tcb->adj_stack_size  = adj_stack_size;
      tcb->stack_alloc_ptr = stack_alloc_ptr;
      tcb->adj_stack_ptr   = adj_stack_ptr;
      ret = OK;
    }
  return ret;
}