os::utils::static_double_list Class Reference

Statically allocated circular double linked list of nodes. More...

#include <cmsis-plus/utils/lists.h>

Inheritance diagram for os::utils::static_double_list:

Public Member Functions
Constructors & Destructor
	static_double_list ()
	Construct a list.
	~static_double_list ()
	Destruct the list.
Public Member Functions
bool	uninitialized (void) const
	Check if the list is uninitialised.
void	clear (void)
	Clear the list.
bool	empty (void) const
	Check if the list is empty.
volatile static_double_list_links *	head (void) const
	Get the list head.
volatile static_double_list_links *	tail (void) const
	Get the list tail.

Protected Member Functions
Private Member Functions
void	insert_after (static_double_list_links &node, static_double_list_links *after)
	Insert a new node after existing node.

Protected Attributes
Private Member Variables
static_double_list_links	head_
	A list node used to point to head and tail.

Detailed Description

This is the simplest list, used as base class for scheduler lists that must be available for any statically constructed thread while still avoiding the 'static initialisation order fiasco'.

The idea is to design the object in such a way as to benefit from the standard BSS initialisation, in other words take nullptr as starting values.

This has the downside of requiring additional tests before adding new nodes to the list, to create the initial self links, and when checking if the list is empty.

Definition at line 341 of file lists.h.

Constructor & Destructor Documentation

static_double_list()

os::utils::static_double_list::static_double_list ( )

inline

The initial list status is empty by having the pointers null.

Definition at line 979 of file lists.h.

    {
      // By all means, do not add any code here.
      // The constructor was not `default` to benefit from inline.
    }

~static_double_list()

os::utils::static_double_list::~static_double_list ( )

inline

There must be no nodes in the list.

Definition at line 989 of file lists.h.

    {
    }

Member Function Documentation

clear()

void os::utils::static_double_list::clear

(

void

)

Parameters

None.

Returns

Nothing.

Initialise the mandatory node with links to itself.

Definition at line 108 of file lists.cpp.

    {
#pragma GCC diagnostic push
#if defined(__clang__)
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
      head_.next (const_cast<static_double_list_links*> (&head_));
      head_.prev (const_cast<static_double_list_links*> (&head_));
#pragma GCC diagnostic pop
    }

References head_, os::utils::static_double_list_links::next(), and os::utils::static_double_list_links::prev().

Referenced by os::utils::double_list::double_list(), os::rtos::internal::ready_threads_list::link(), and os::rtos::internal::terminated_threads_list::link().

empty()

bool os::utils::static_double_list::empty ( void  ) const

inline

Parameters

None.

Return values

true	The list has no nodes.
false	The list has at least one node.

Definition at line 1001 of file lists.h.

    {
      // If it points to itself, it is empty.
      return (head_.next () == &head_) || (head_.next () == nullptr);
    }

References head_, and os::utils::static_double_list_links::next().

Referenced by os::utils::double_list::~double_list(), os::rtos::internal::clock_timestamps_list::check_timestamp(), os::rtos::internal::clock_timestamps_list::link(), os::rtos::internal::ready_threads_list::link(), os::rtos::internal::waiting_threads_list::link(), os::rtos::internal::waiting_threads_list::resume_one(), and os::rtos::internal::ready_threads_list::unlink_head().

head()

volatile static_double_list_links * os::utils::static_double_list::head ( void  ) const

inline

Parameters

None.

Returns

Pointer to head node.

Definition at line 1008 of file lists.h.

    {
      return static_cast<volatile static_double_list_links*> (head_.next ());
    }

References head_, and os::utils::static_double_list_links::next().

insert_after()

void os::utils::static_double_list::insert_after ( static_double_list_links &  node, static_double_list_links *  after  )

protected

Parameters

node	Reference to node to insert.
after	Reference to existing node.

Returns

Nothing.

Definition at line 121 of file lists.cpp.

    {
#if defined(OS_TRACE_UTILS_LISTS)
      trace::printf ("%s() n=%p after %p\n", __func__, &node, after);
#endif
 
      // Unlinked nodes must have both pointers null.
      // If not, most probably the node was already linked.
      // Or the memory is corrupted.
      assert (node.prev () == nullptr);
      assert (node.next () == nullptr);
 
      // The `after` node must be linked. Only the `next` pointer is
      // tested, since only it is used.
      assert (after->next () != nullptr);
 
      // Make the new node point to its neighbours.
      node.prev (after);
      node.next (after->next ());
 
      // Make the neighbours point to the node. The order is important.
      after->next ()->prev (&node);
      after->next (&node);
    }

References os::utils::static_double_list_links::next(), os::utils::static_double_list_links::prev(), and os::trace::printf().

Referenced by os::rtos::internal::thread_children_list::link(), os::rtos::internal::clock_timestamps_list::link(), os::rtos::internal::ready_threads_list::link(), os::rtos::internal::waiting_threads_list::link(), and os::rtos::internal::terminated_threads_list::link().

tail()

volatile static_double_list_links * os::utils::static_double_list::tail ( void  ) const

inline

Parameters

None.

Returns

Pointer to tail node.

Definition at line 1014 of file lists.h.

    {
      return (head_.prev ());
    }

References head_, and os::utils::static_double_list_links::prev().

Referenced by os::rtos::internal::thread_children_list::link(), os::rtos::internal::clock_timestamps_list::link(), os::rtos::internal::ready_threads_list::link(), os::rtos::internal::waiting_threads_list::link(), and os::rtos::internal::terminated_threads_list::link().

uninitialized()

bool os::utils::static_double_list::uninitialized ( void  ) const

inline

Parameters

None.

Return values

true	The list was not initialised.
false	The list was initialised.

Definition at line 994 of file lists.h.

    {
      // If it points to nowhere, it is not yet initialised.
      return (head_.prev () == nullptr);
    }

References head_, and os::utils::static_double_list_links::prev().

Member Data Documentation

head_

static_double_list_links os::utils::static_double_list::head_

protected

To simplify processing, the list always has a node.

Definition at line 473 of file lists.h.

Referenced by os::rtos::internal::waiting_threads_list::begin(), os::rtos::internal::clock_timestamps_list::check_timestamp(), clear(), empty(), os::rtos::internal::waiting_threads_list::end(), head(), os::rtos::internal::clock_timestamps_list::link(), os::rtos::internal::ready_threads_list::link(), os::rtos::internal::waiting_threads_list::link(), os::rtos::internal::terminated_threads_list::link(), tail(), and uninitialized().

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The documentation for this class was generated from the following files:

• lists.h
• lists.cpp