path: root/cpukit/include/rtems/score/stackimpl.h

/**
 * @file
 *
 * @ingroup RTEMSScoreStack
 *
 * @brief This header file provides interfaces of the
 *   @ref RTEMSScoreStack which are only used by the implementation.
 */

/*
 *  COPYRIGHT (c) 1989-2006.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.org/license/LICENSE.
 */

#ifndef _RTEMS_SCORE_STACKIMPL_H
#define _RTEMS_SCORE_STACKIMPL_H

#include <rtems/score/stack.h>
#include <rtems/score/context.h>
#include <rtems/score/tls.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @addtogroup RTEMSScoreStack
 *
 * @{
 */

/**
 * @brief Initializes stack with the given starting address and size.
 *
 * This routine initializes the_stack record to indicate that
 * size bytes of memory starting at starting_address have been
 * reserved for a stack.
 *
 * @param[out] the_stack The stack to initialize.
 * @param starting_address The starting_address for the new stack.
 * @param size The size of the stack in bytes.
 */
RTEMS_INLINE_ROUTINE void _Stack_Initialize (
  Stack_Control *the_stack,
  void          *starting_address,
  size_t         size
)
{
  the_stack->area = starting_address;
  the_stack->size = size;
}

/**
 * @brief Returns the minimum stack size.
 *
 * This function returns the minimum stack size configured
 * for this application.
 *
 * @return The minimum stack size.
 */
RTEMS_INLINE_ROUTINE uint32_t _Stack_Minimum (void)
{
  return rtems_minimum_stack_size;
}

/**
 * @brief Checks if the size is enough for a valid stack area on this processor.
 *
 * This function returns true if size bytes is enough memory for
 * a valid stack area on this processor, and false otherwise.
 *
 * @param size The stack size to check.
 * @param is_fp Indicates if the stack is for a floating-point thread.
 *
 * @retval true @a size is large enough.
 * @retval false @a size is not large enough.
 */
RTEMS_INLINE_ROUTINE bool _Stack_Is_enough(
  size_t size,
  bool   is_fp
)
{
  size_t minimum;

  minimum = _TLS_Get_allocation_size();
  minimum += _Stack_Minimum();

#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
  if ( is_fp ) {
    minimum += CONTEXT_FP_SIZE;
  }
#endif

  return ( size >= minimum );
}

/**
 * @brief Returns the appropriate stack size for the requested size.
 *
 * This function returns the appropriate stack size given the requested
 * size.  If the requested size is below the minimum, then the minimum
 * configured stack size is returned.
 *
 * @param size The stack size to check.
 *
 * @return The appropriate stack size.
 */
RTEMS_INLINE_ROUTINE size_t _Stack_Ensure_minimum (
  size_t size
)
{
  if ( size >= _Stack_Minimum() )
    return size;
  return _Stack_Minimum();
}

/**
 * @brief Extends the stack size to account for additional data structures
 *   allocated in the thread storage area.
 *
 * @param stack_size is the stack size.
 *
 * @param is_fp shall be true, if the stack is for a floating-point thread,
 *   otherwise it shall be false.
 *
 * @return Returns the extended stack size.
 */
RTEMS_INLINE_ROUTINE size_t _Stack_Extend_size(
  size_t stack_size,
  bool   is_fp
)
{
  size_t extra_size;
  size_t allocator_overhead;

  extra_size = _TLS_Get_allocation_size();

#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
  if ( is_fp ) {
    /* This addition cannot overflow since the TLS size cannot be that large */
    extra_size += CONTEXT_FP_SIZE;
  }
#else
  (void) is_fp;
#endif

  /*
   * In order to make sure that a user-provided stack size is the minimum which
   * can be allocated for the stack, we have to align it up to the next stack
   * boundary.
   */
  extra_size += CPU_STACK_ALIGNMENT - 1;

  /*
   * If the heap allocator does not meet the stack alignment requirement, then
   * we have to do the stack alignment manually in _Thread_Initialize() and
   * need to allocate extra space for this.
   */
  allocator_overhead = CPU_STACK_ALIGNMENT - CPU_HEAP_ALIGNMENT;

  if ( stack_size > SIZE_MAX - extra_size - allocator_overhead ) {
    /*
     * In case of an unsigned integer overflow, saturate at the maximum value.
     */
    return SIZE_MAX;
  }

  stack_size += extra_size;
  stack_size = RTEMS_ALIGN_DOWN( stack_size, CPU_STACK_ALIGNMENT );

  return stack_size + allocator_overhead;
}

/**
 * @brief Allocate the requested stack space.
 *
 * @param stack_size The stack space that is requested.
 *
 * @retval stack_area The allocated stack area.
 * @retval NULL The allocation failed.
 */
void *_Stack_Allocate( size_t stack_size );

/**
 * @brief Free the stack area allocated by _Stack_Allocate().
 *
 * Do nothing if the stack area is NULL.
 *
 * @param stack_area The stack area to free, or NULL.
 */
void _Stack_Free( void *stack_area );

/** @} */

#ifdef __cplusplus
}
#endif

#endif
/* end of include file */