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Diffstat (limited to 'cpukit/include/rtems/score/chainimpl.h')
| -rw-r--r-- | cpukit/include/rtems/score/chainimpl.h | 1123 |
1 files changed, 1123 insertions, 0 deletions
diff --git a/cpukit/include/rtems/score/chainimpl.h b/cpukit/include/rtems/score/chainimpl.h new file mode 100644 index 0000000000..c94c051198 --- /dev/null +++ b/cpukit/include/rtems/score/chainimpl.h @@ -0,0 +1,1123 @@ +/** + * @file + * + * @brief Chain Handler API + */ + +/* + * Copyright (c) 2010 embedded brains GmbH. + * + * COPYRIGHT (c) 1989-2014. + * 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_CHAINIMPL_H +#define _RTEMS_SCORE_CHAINIMPL_H + +#include <rtems/score/chain.h> +#include <rtems/score/address.h> +#include <rtems/score/assert.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @addtogroup ScoreChain + */ +/**@{**/ + +/** + * @brief Chain initializer for an empty chain with designator @a name. + */ +#define CHAIN_INITIALIZER_EMPTY(name) \ + { { { &(name).Tail.Node, NULL }, &(name).Head.Node } } + +/** + * @brief Chain initializer for a chain with one @a node. + * + * @see CHAIN_NODE_INITIALIZER_ONE_NODE_CHAIN(). + */ +#define CHAIN_INITIALIZER_ONE_NODE( node ) \ + { { { (node), NULL }, (node) } } + +/** + * @brief Chain node initializer for a @a chain containing exactly this node. + * + * @see CHAIN_INITIALIZER_ONE_NODE(). + */ +#define CHAIN_NODE_INITIALIZER_ONE_NODE_CHAIN( chain ) \ + { &(chain)->Tail.Node, &(chain)->Head.Node } + +/** + * @brief Chain definition for an empty chain with designator @a name. + */ +#define CHAIN_DEFINE_EMPTY(name) \ + Chain_Control name = CHAIN_INITIALIZER_EMPTY(name) + +/** + * @brief Initialize a chain header. + * + * This routine initializes @a the_chain structure to manage the + * contiguous array of @a number_nodes nodes which starts at + * @a starting_address. Each node is of @a node_size bytes. + * + * @param[in] the_chain specifies the chain to initialize + * @param[in] starting_address is the starting address of the array + * of elements + * @param[in] number_nodes is the numebr of nodes that will be in the chain + * @param[in] node_size is the size of each node + */ +void _Chain_Initialize( + Chain_Control *the_chain, + void *starting_address, + size_t number_nodes, + size_t node_size +); + +/** + * @brief Returns the node count of the chain. + * + * @param[in] chain The chain. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * operation. + * + * @retval The node count of the chain. + */ +size_t _Chain_Node_count_unprotected( const Chain_Control *chain ); + +/** + * @brief Set off chain. + * + * This function sets the next field of the @a node to NULL indicating the @a + * node is not part of a chain. + * + * @param[in] node the node set to off chain. + */ +RTEMS_INLINE_ROUTINE void _Chain_Set_off_chain( + Chain_Node *node +) +{ + node->next = NULL; +#if defined(RTEMS_DEBUG) + node->previous = NULL; +#endif +} + +/** + * @brief Initializes a chain node. + * + * In debug configurations, the node is set off chain. In all other + * configurations, this function does nothing. + * + * @param[in] the_node The chain node to initialize. + */ +RTEMS_INLINE_ROUTINE void _Chain_Initialize_node( Chain_Node *the_node ) +{ +#if defined(RTEMS_DEBUG) + _Chain_Set_off_chain( the_node ); +#else + (void) the_node; +#endif +} + +/** + * @brief Is the node off chain. + * + * This function returns true if the @a node is not on a chain. A @a node is + * off chain if the next field is set to NULL. + * + * @param[in] node is the node off chain. + * + * @retval true The @a node is off chain. + * @retval false The @a node is not off chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_node_off_chain( + const Chain_Node *node +) +{ + return node->next == NULL; +} + +/** + * @brief Are two nodes equal. + * + * This function returns true if @a left and @a right are equal, + * and false otherwise. + * + * @param[in] left is the node on the left hand side of the comparison. + * @param[in] right is the node on the left hand side of the comparison. + * + * @retval true @a left and @a right are equal. + * @retval false @a left and @a right are not equal. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Are_nodes_equal( + const Chain_Node *left, + const Chain_Node *right +) +{ + return left == right; +} + +/** + * @brief Is the chain node pointer NULL. + * + * This function returns true if the_node is NULL and false otherwise. + * + * @param[in] the_node is the node pointer to check. + * + * @retval true @a the_node is @c NULL. + * @retval false @a the_node is not @c NULL. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_null_node( + const Chain_Node *the_node +) +{ + return (the_node == NULL); +} + +/** + * @brief Return pointer to chain head. + * + * This function returns a pointer to the head node on the chain. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the permanent head node of the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Head( + Chain_Control *the_chain +) +{ + return &the_chain->Head.Node; +} + +/** + * @brief Return pointer to immutable chain head. + * + * This function returns a pointer to the head node on the chain. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the permanent head node of the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_head( + const Chain_Control *the_chain +) +{ + return &the_chain->Head.Node; +} + +/** + * @brief Return pointer to chain tail. + * + * This function returns a pointer to the tail node on the chain. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the permanent tail node of the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Tail( + Chain_Control *the_chain +) +{ + return &the_chain->Tail.Node; +} + +/** + * @brief Return pointer to immutable chain tail. + * + * This function returns a pointer to the tail node on the chain. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the permanent tail node of the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_tail( + const Chain_Control *the_chain +) +{ + return &the_chain->Tail.Node; +} + +/** + * @brief Return pointer to chain's first node. + * + * This function returns a pointer to the first node on the chain after the + * head. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the first node of the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_First( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_head( the_chain )->next; +} + +/** + * @brief Return pointer to immutable chain's first node. + * + * This function returns a pointer to the first node on the chain after the + * head. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the first node of the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_first( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_head( the_chain )->next; +} + +/** + * @brief Return pointer to chain's last node. + * + * This function returns a pointer to the last node on the chain just before + * the tail. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the last node of the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Last( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_tail( the_chain )->previous; +} + +/** + * @brief Return pointer to immutable chain's last node. + * + * This function returns a pointer to the last node on the chain just before + * the tail. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This method returns the last node of the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_last( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_tail( the_chain )->previous; +} + +/** + * @brief Return pointer the next node from this node. + * + * This function returns a pointer to the next node after this node. + * + * @param[in] the_node is the node to be operated upon. + * + * @return This method returns the next node on the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Next( + const Chain_Node *the_node +) +{ + return the_node->next; +} + +/** + * @brief Return pointer the immutable next node from this node. + * + * This function returns a pointer to the next node after this node. + * + * @param[in] the_node is the node to be operated upon. + * + * @return This method returns the next node on the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_next( + const Chain_Node *the_node +) +{ + return the_node->next; +} + +/** + * @brief Return pointer the previous node from this node. + * + * This function returns a pointer to the previous node on this chain. + * + * @param[in] the_node is the node to be operated upon. + * + * @return This method returns the previous node on the chain. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Previous( + const Chain_Node *the_node +) +{ + return the_node->previous; +} + +/** + * @brief Return pointer the immutable previous node from this node. + * + * This function returns a pointer to the previous node on this chain. + * + * @param[in] the_node is the node to be operated upon. + * + * @return This method returns the previous node on the chain. + */ +RTEMS_INLINE_ROUTINE const Chain_Node *_Chain_Immutable_previous( + const Chain_Node *the_node +) +{ + return the_node->previous; +} + +/** + * @brief Is the chain empty. + * + * This function returns true if there a no nodes on @a the_chain and + * false otherwise. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @retval true There are no nodes on @a the_chain. + * @retval false There are nodes on @a the_chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_empty( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_first( the_chain ) + == _Chain_Immutable_tail( the_chain ); +} + +/** + * @brief Is this the first node on the chain. + * + * This function returns true if the_node is the first node on a chain and + * false otherwise. + * + * @param[in] the_node is the node the caller wants to know if it is + * the first node on a chain. + * + * @retval true @a the_node is the first node on a chain. + * @retval false @a the_node is not the first node on a chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_first( + const Chain_Node *the_node +) +{ + return (the_node->previous->previous == NULL); +} + +/** + * @brief Is this the last node on the chain. + * + * This function returns true if @a the_node is the last node on a chain and + * false otherwise. + * + * @param[in] the_node is the node to check as the last node. + * + * @retval true @a the_node is the last node on a chain. + * @retval false @a the_node is not the last node on a chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_last( + const Chain_Node *the_node +) +{ + return (the_node->next->next == NULL); +} + +/** + * @brief Does this chain have only one node. + * + * This function returns true if there is only one node on @a the_chain and + * false otherwise. + * + * @param[in] the_chain is the chain to be operated upon. + * + * @return This function returns true if there is only one node on + * @a the_chain and false otherwise. + * + * @retval true There is only one node on @a the_chain. + * @retval false There is more than one node on @a the_chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Has_only_one_node( + const Chain_Control *the_chain +) +{ + return _Chain_Immutable_first( the_chain ) + == _Chain_Immutable_last( the_chain ); +} + +/** + * @brief Is this node the chain head. + * + * This function returns true if @a the_node is the head of @a the_chain and + * false otherwise. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to check for being the Chain Head. + * + * @retval true @a the_node is the head of @a the_chain. + * @retval false @a the_node is not the head of @a the_chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_head( + const Chain_Control *the_chain, + const Chain_Node *the_node +) +{ + return (the_node == _Chain_Immutable_head( the_chain )); +} + +/** + * @brief Is this node the chail tail. + * + * This function returns true if @a the_node is the tail of @a the_chain and + * false otherwise. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to check for being the Chain Tail. + * + * @retval true @a the_node is the tail of @a the_chain. + * @retval false @a the_node is not the tail of @a the_chain. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Is_tail( + const Chain_Control *the_chain, + const Chain_Node *the_node +) +{ + return (the_node == _Chain_Immutable_tail( the_chain )); +} + +/** + * @brief Initialize this chain as empty. + * + * This routine initializes the specified chain to contain zero nodes. + * + * @param[in] the_chain is the chain to be initialized. + */ +RTEMS_INLINE_ROUTINE void _Chain_Initialize_empty( + Chain_Control *the_chain +) +{ + Chain_Node *head; + Chain_Node *tail; + + _Assert( the_chain != NULL ); + + head = _Chain_Head( the_chain ); + tail = _Chain_Tail( the_chain ); + + head->next = tail; + head->previous = NULL; + tail->previous = head; +} + +/** + * @brief Initializes this chain to contain exactly the specified node. + * + * @param[in] the_chain The chain control. + * @param[in] the_node The one and only node. + */ +RTEMS_INLINE_ROUTINE void _Chain_Initialize_one( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + Chain_Node *head; + Chain_Node *tail; + + _Assert( _Chain_Is_node_off_chain( the_node ) ); + + head = _Chain_Head( the_chain ); + tail = _Chain_Tail( the_chain ); + + the_node->next = tail; + the_node->previous = head; + + head->next = the_node; + head->previous = NULL; + tail->previous = the_node; +} + +/** + * @brief Extract this node (unprotected). + * + * This routine extracts the_node from the chain on which it resides. + * It does NOT disable interrupts to ensure the atomicity of the + * extract operation. + * + * @param[in] the_node is the node to be extracted. + */ +RTEMS_INLINE_ROUTINE void _Chain_Extract_unprotected( + Chain_Node *the_node +) +{ + Chain_Node *next; + Chain_Node *previous; + + next = the_node->next; + previous = the_node->previous; + next->previous = previous; + previous->next = next; + +#if defined(RTEMS_DEBUG) + _Chain_Set_off_chain( the_node ); +#endif +} + +/** + * @brief Get the first node (unprotected). + * + * This function removes the first node from the_chain and returns + * a pointer to that node. It does NOT disable interrupts to ensure + * the atomicity of the get operation. + * + * @param[in] the_chain is the chain to attempt to get the first node from. + * + * @return This method returns the first node on the chain even if it is + * the Chain Tail. + * + * @note This routine assumes that there is at least one node on the chain + * and always returns a node even if it is the Chain Tail. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Get_first_unprotected( + Chain_Control *the_chain +) +{ + Chain_Node *head; + Chain_Node *old_first; + Chain_Node *new_first; + + _Assert( !_Chain_Is_empty( the_chain ) ); + + head = _Chain_Head( the_chain ); + old_first = head->next; + new_first = old_first->next; + + head->next = new_first; + new_first->previous = head; + +#if defined(RTEMS_DEBUG) + _Chain_Set_off_chain( old_first ); +#endif + + return old_first; +} + +/** + * @brief Get the first node (unprotected). + * + * This function removes the first node from the_chain and returns + * a pointer to that node. If the_chain is empty, then NULL is returned. + * + * @param[in] the_chain is the chain to attempt to get the first node from. + * + * @return This method returns the first node on the chain or NULL if the + * chain is empty. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * get operation. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Get_unprotected( + Chain_Control *the_chain +) +{ + if ( !_Chain_Is_empty(the_chain)) + return _Chain_Get_first_unprotected(the_chain); + else + return NULL; +} + +/** + * @brief Insert a node (unprotected). + * + * This routine inserts the_node on a chain immediately following + * after_node. + * + * @param[in] after_node is the node which will precede @a the_node on the + * chain. + * @param[in] the_node is the node to be inserted. + * + * @note It does NOT disable interrupts to ensure the atomicity + * of the extract operation. + */ +RTEMS_INLINE_ROUTINE void _Chain_Insert_unprotected( + Chain_Node *after_node, + Chain_Node *the_node +) +{ + Chain_Node *before_node; + + _Assert( _Chain_Is_node_off_chain( the_node ) ); + + the_node->previous = after_node; + before_node = after_node->next; + after_node->next = the_node; + the_node->next = before_node; + before_node->previous = the_node; +} + +/** + * @brief Append a node (unprotected). + * + * This routine appends the_node onto the end of the_chain. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to be appended. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * append operation. + */ +RTEMS_INLINE_ROUTINE void _Chain_Append_unprotected( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + Chain_Node *tail; + Chain_Node *old_last; + + _Assert( _Chain_Is_node_off_chain( the_node ) ); + + tail = _Chain_Tail( the_chain ); + old_last = tail->previous; + + the_node->next = tail; + tail->previous = the_node; + old_last->next = the_node; + the_node->previous = old_last; +} + +/** + * @brief Append a node on the end of a chain if the node is in the off chain + * state (unprotected). + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * append operation. + * + * @see _Chain_Append_unprotected() and _Chain_Is_node_off_chain(). + */ +RTEMS_INLINE_ROUTINE void _Chain_Append_if_is_off_chain_unprotected( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + if ( _Chain_Is_node_off_chain( the_node ) ) { + _Chain_Append_unprotected( the_chain, the_node ); + } +} + +/** + * @brief Prepend a node (unprotected). + * + * This routine prepends the_node onto the front of the_chain. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to be prepended. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * prepend operation. + */ +RTEMS_INLINE_ROUTINE void _Chain_Prepend_unprotected( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + _Chain_Insert_unprotected(_Chain_Head(the_chain), the_node); +} + +/** + * @brief Append a node and check if the chain was empty before (unprotected). + * + * This routine appends the_node onto the end of the_chain. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to be appended. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * append operation. + * + * @retval true The chain was empty before. + * @retval false The chain contained at least one node before. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Append_with_empty_check_unprotected( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + bool was_empty = _Chain_Is_empty( the_chain ); + + _Chain_Append_unprotected( the_chain, the_node ); + + return was_empty; +} + +/** + * @brief Prepend a node and check if the chain was empty before (unprotected). + * + * This routine prepends the_node onto the front of the_chain. + * + * @param[in] the_chain is the chain to be operated upon. + * @param[in] the_node is the node to be prepended. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * prepend operation. + * + * @retval true The chain was empty before. + * @retval false The chain contained at least one node before. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Prepend_with_empty_check_unprotected( + Chain_Control *the_chain, + Chain_Node *the_node +) +{ + bool was_empty = _Chain_Is_empty( the_chain ); + + _Chain_Prepend_unprotected( the_chain, the_node ); + + return was_empty; +} + +/** + * @brief Get the first node and check if the chain is empty afterwards + * (unprotected). + * + * This function removes the first node from the_chain and returns + * a pointer to that node in @a the_node. If the_chain is empty, then NULL is + * returned. + * + * @param[in] the_chain is the chain to attempt to get the first node from. + * @param[out] the_node is the first node on the chain or NULL if the chain is + * empty. + * + * @note It does NOT disable interrupts to ensure the atomicity of the + * get operation. + * + * @retval true The chain is empty now. + * @retval false The chain contains at least one node now. + */ +RTEMS_INLINE_ROUTINE bool _Chain_Get_with_empty_check_unprotected( + Chain_Control *the_chain, + Chain_Node **the_node +) +{ + bool is_empty_now = true; + Chain_Node *head = _Chain_Head( the_chain ); + Chain_Node *tail = _Chain_Tail( the_chain ); + Chain_Node *old_first = head->next; + + if ( old_first != tail ) { + Chain_Node *new_first = old_first->next; + + head->next = new_first; + new_first->previous = head; + + *the_node = old_first; + + is_empty_now = new_first == tail; + } else + *the_node = NULL; + + return is_empty_now; +} + +/** + * @brief Chain node order. + * + * @param[in] left The left hand side. + * @param[in] right The right hand side. + * + * @retval true According to the order the left node precedes the right node. + * @retval false Otherwise. + */ +typedef bool ( *Chain_Node_order )( + const void *left, + const Chain_Node *right +); + +/** + * @brief Inserts a node into the chain according to the order relation. + * + * After the operation the chain contains the node to insert and the order + * relation holds for all nodes from the head up to the inserted node. Nodes + * after the inserted node are not moved. + * + * @param[in] the_chain The chain. + * @param[in] to_insert The node to insert. + * @param[in] left The left hand side passed to the order relation. It must + * correspond to the node to insert. The separate left hand side parameter + * may help the compiler to generate better code if it is stored in a local + * variable. + * @param[in] order The order relation. + */ +RTEMS_INLINE_ROUTINE void _Chain_Insert_ordered_unprotected( + Chain_Control *the_chain, + Chain_Node *to_insert, + const void *left, + Chain_Node_order order +) +{ + const Chain_Node *tail = _Chain_Immutable_tail( the_chain ); + Chain_Node *next = _Chain_First( the_chain ); + + while ( next != tail && !( *order )( left, next ) ) { + next = _Chain_Next( next ); + } + + _Chain_Insert_unprotected( _Chain_Previous( next ), to_insert ); +} + +/** + * @brief The chain iterator direction. + */ +typedef enum { + /** + * @brief Iteration from head to tail. + */ + CHAIN_ITERATOR_FORWARD, + + /** + * @brief Iteration from tail to head. + */ + CHAIN_ITERATOR_BACKWARD +} Chain_Iterator_direction; + +/** + * @brief A chain iterator which is updated during node extraction if it is + * properly registered. + * + * @see _Chain_Iterator_initialize(). + */ +typedef struct { + /** + * @brief Node for registration. + * + * Used during _Chain_Iterator_initialize() and _Chain_Iterator_destroy(). + */ + Chain_Node Registry_node; + + /** + * @brief The direction of this iterator. + * + * Immutable after initialization via _Chain_Iterator_initialize(). + */ + Chain_Iterator_direction direction; + + /** + * @brief The current position of this iterator. + * + * The position is initialized via _Chain_Iterator_initialize(). It must be + * explicitly set after one valid iteration step, e.g. in case a next node in + * the iterator direction existed. It is updated through the registration in + * case a node is extracted via _Chain_Iterator_registry_update(). + */ + Chain_Node *position; +} Chain_Iterator; + +/** + * @brief A registry for chain iterators. + * + * Should be attached to a chain control to enable safe iteration through a + * chain in case of concurrent node extractions. + */ +typedef struct { + Chain_Control Iterators; +} Chain_Iterator_registry; + +/** + * @brief Chain iterator registry initializer for static initialization. + * + * @param name The designator of the chain iterator registry. + */ +#define CHAIN_ITERATOR_REGISTRY_INITIALIZER( name ) \ + { CHAIN_INITIALIZER_EMPTY( name.Iterators ) } + +/** + * @brief Initializes a chain iterator registry. + */ +RTEMS_INLINE_ROUTINE void _Chain_Iterator_registry_initialize( + Chain_Iterator_registry *the_registry +) +{ + _Chain_Initialize_empty( &the_registry->Iterators ); +} + +/** + * @brief Updates all iterators present in the chain iterator registry in case + * of a node extraction. + * + * Must be called before _Chain_Extract_unprotected(). + * + * @warning This function will look at all registered chain iterators to + * determine if an update is necessary. + */ +RTEMS_INLINE_ROUTINE void _Chain_Iterator_registry_update( + Chain_Iterator_registry *the_registry, + Chain_Node *the_node_to_extract +) +{ + Chain_Node *iter_node; + Chain_Node *iter_tail; + + iter_node = _Chain_Head( &the_registry->Iterators ); + iter_tail = _Chain_Tail( &the_registry->Iterators ); + + while ( ( iter_node = _Chain_Next( iter_node ) ) != iter_tail ) { + Chain_Iterator *iter; + + iter = (Chain_Iterator *) iter_node; + + if ( iter->position == the_node_to_extract ) { + if ( iter->direction == CHAIN_ITERATOR_FORWARD ) { + iter->position = _Chain_Previous( the_node_to_extract ); + } else { + iter->position = _Chain_Next( the_node_to_extract ); + } + } + } +} + +/** + * @brief Initializes the chain iterator. + * + * In the following example nodes inserted during the iteration are visited in + * case they are inserted after the current position in iteration order. + * + * @code + * #include <rtems/score/chainimpl.h> + * #include <rtems/score/isrlock.h> + * + * typedef struct { + * Chain_Control Chain; + * Chain_Iterator_registry Iterators; + * ISR_LOCK_MEMBER( Lock ) + * } Some_Control; + * + * void iterate( + * Some_Control *the_some, + * void ( *visitor )( Chain_Node * ) + * ) + * { + * ISR_lock_Context lock_context; + * Chain_Iterator iter; + * Chain_Node *node; + * const Chain_Node *end; + * + * end = _Chain_Immutable_tail( &the_some->Chain ); + * + * _ISR_lock_ISR_disable_and_acquire( &the_some->Lock, &lock_context ); + * + * _Chain_Iterator_initialize( + * &the_some->Chain, + * &the_some->Iterators, + * &iter, + * CHAIN_ITERATOR_FORWARD + * ); + * + * while ( ( node = _Chain_Iterator_next( &iter ) ) != end ) { + * _Chain_Iterator_set_position( &iter, node ); + * _ISR_lock_Release_and_ISR_enable( &the_some->Lock, &lock_context ); + * ( *visitor )( node ); + * _ISR_lock_ISR_disable_and_acquire( &the_some->Lock, &lock_context ); + * } + * + * _Chain_Iterator_destroy( &iter ); + * _ISR_lock_Release_and_ISR_enable( &the_some->Lock, &lock_context ); + * } + * @endcode + * + * @param the_chain The chain to iterate. + * @param the_registry The registry for the chain iterator. + * @param the_iterator The chain iterator to initialize. + * @param direction The iteration direction. + * + * @see _Chain_Iterator_next(), _Chain_Iterator_set_position() and + * Chain_Iterator_destroy(). + * + * @warning Think twice before you use a chain iterator. Its current + * implementation is unfit for use in performance relevant components, due to + * the linear time complexity in _Chain_Iterator_registry_update(). + */ +RTEMS_INLINE_ROUTINE void _Chain_Iterator_initialize( + Chain_Control *the_chain, + Chain_Iterator_registry *the_registry, + Chain_Iterator *the_iterator, + Chain_Iterator_direction direction +) +{ + _Chain_Initialize_node( &the_iterator->Registry_node ); + _Chain_Append_unprotected( + &the_registry->Iterators, + &the_iterator->Registry_node + ); + + the_iterator->direction = direction; + + if ( direction == CHAIN_ITERATOR_FORWARD ) { + the_iterator->position = _Chain_Head( the_chain ); + } else { + the_iterator->position = _Chain_Tail( the_chain ); + } +} + +/** + * @brief Returns the next node in the iterator direction. + * + * In case a next node exists, then the iterator should be updated via + * _Chain_Iterator_set_position() to continue with the next iteration step. + * + * @param the_iterator The chain iterator. + */ +RTEMS_INLINE_ROUTINE Chain_Node *_Chain_Iterator_next( + const Chain_Iterator *the_iterator +) +{ + if ( the_iterator->direction == CHAIN_ITERATOR_FORWARD ) { + return _Chain_Next( the_iterator->position ); + } else { + return _Chain_Previous( the_iterator->position ); + } +} + +/** + * @brief Sets the iterator position. + * + * @param the_iterator The chain iterator. + * @param the_node The new iterator position. + */ +RTEMS_INLINE_ROUTINE void _Chain_Iterator_set_position( + Chain_Iterator *the_iterator, + Chain_Node *the_node +) +{ + the_iterator->position = the_node; +} + +/** + * @brief Destroys the iterator. + * + * Removes the iterator from its registry. + * + * @param the_iterator The chain iterator. + */ +RTEMS_INLINE_ROUTINE void _Chain_Iterator_destroy( + Chain_Iterator *the_iterator +) +{ + _Chain_Extract_unprotected( &the_iterator->Registry_node ); +} + +/** @} */ + +#ifdef __cplusplus +} +#endif + +#endif +/* end of include file */ |