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/*
* IoT Common V1.1.0
* Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/**
* @file iot_static_memory.h
* @brief Common functions for managing static buffers. Only used when
* @ref IOT_STATIC_MEMORY_ONLY is `1`.
*/
/* The config header is always included first. */
#include "iot_config.h"
/* The functions in this file should only exist in static memory only mode, hence
* the check for IOT_STATIC_MEMORY_ONLY in the double inclusion guard. */
#if !defined( IOT_STATIC_MEMORY_H_ ) && ( IOT_STATIC_MEMORY_ONLY == 1 )
#define IOT_STATIC_MEMORY_H_
/* Standard includes. */
#include <stddef.h>
#include <stdint.h>
/**
* @functionspage{static_memory,static memory component}
* - @functionname{static_memory_function_findfree}
* - @functionname{static_memory_function_returninuse}
* - @functionname{static_memory_function_messagebuffersize}
* - @functionname{static_memory_function_mallocmessagebuffer}
* - @functionname{static_memory_function_freemessagebuffer}
*/
/*------------------------- Buffer allocation and free ----------------------*/
/**
* @functionpage{IotStaticMemory_FindFree,static_memory,findfree}
* @functionpage{IotStaticMemory_ReturnInUse,static_memory,returninuse}
*/
/**
* @brief Find a free buffer using the "in-use" flags.
*
* If a free buffer is found, this function marks the buffer in-use. This function
* is common to the static memory implementation.
*
* @param[in] pInUse The "in-use" flags to search.
* @param[in] limit How many flags to check, i.e. the size of `pInUse`.
*
* @return The index of a free buffer; `-1` if no free buffers are available.
*
* <b>Example</b>:
* @code{c}
* // To use this function, first declare two arrays. One provides the statically-allocated
* // objects, the other provides flags to determine which objects are in-use.
* #define NUMBER_OF_OBJECTS ...
* #define OBJECT_SIZE ...
* static uint32_t _pInUseObjects[ NUMBER_OF_OBJECTS ] = { 0 };
* static uint8_t _pObjects[ NUMBER_OF_OBJECTS ][ OBJECT_SIZE ] = { { 0 } }; // Placeholder for objects.
*
* // The function to statically allocate objects. Must have the same signature
* // as malloc().
* void * Iot_MallocObject( size_t size )
* {
* int32_t freeIndex = -1;
* void * pNewObject = NULL;
*
* // Check that sizes match.
* if( size != OBJECT_SIZE )
* {
* // Get the index of a free object.
* freeIndex = IotStaticMemory_FindFree( _pInUseMessageBuffers,
* IOT_MESSAGE_BUFFERS );
*
* if( freeIndex != -1 )
* {
* pNewBuffer = &( _pMessageBuffers[ freeIndex ][ 0 ] );
* }
* }
*
* return pNewBuffer;
* }
* @endcode
*/
/* @[declare_static_memory_findfree] */
int32_t IotStaticMemory_FindFree( uint32_t * pInUse,
size_t limit );
/* @[declare_static_memory_findfree] */
/**
* @brief Return an "in-use" buffer.
*
* This function is common to the static memory implementation.
*
* @param[in] ptr Pointer to the buffer to return.
* @param[in] pPool The pool of buffers that the in-use buffer was allocated from.
* @param[in] pInUse The "in-use" flags for pPool.
* @param[in] limit How many buffers (and flags) to check while searching for ptr.
* @param[in] elementSize The size of a single element in pPool.
*
* <b>Example</b>:
* @code{c}
* // To use this function, first declare two arrays. One provides the statically-allocated
* // objects, the other provides flags to determine which objects are in-use.
* #define NUMBER_OF_OBJECTS ...
* #define OBJECT_SIZE ...
* static uint32_t _pInUseObjects[ NUMBER_OF_OBJECTS ] = { 0 };
* static uint8_t _pObjects[ NUMBER_OF_OBJECTS ][ OBJECT_SIZE ] = { { 0 } }; // Placeholder for objects.
*
* // The function to free statically-allocated objects. Must have the same signature
* // as free().
* void Iot_FreeObject( void * ptr )
* {
* IotStaticMemory_ReturnInUse( ptr,
* _pObjects,
* _pInUseObjects,
* NUMBER_OF_OBJECTS,
* OBJECT_SIZE );
* }
* @endcode
*/
/* @[declare_static_memory_returninuse] */
void IotStaticMemory_ReturnInUse( void * ptr,
void * pPool,
uint32_t * pInUse,
size_t limit,
size_t elementSize );
/* @[declare_static_memory_returninuse] */
/*------------------------ Message buffer management ------------------------*/
/**
* @functionpage{Iot_MessageBufferSize,static_memory,messagebuffersize}
* @functionpage{Iot_MallocMessageBuffer,static_memory,mallocmessagebuffer}
* @functionpage{Iot_FreeMessageBuffer,static_memory,freemessagebuffer}
*/
/**
* @brief Get the fixed size of a message buffer.
*
* The size of the message buffers are known at compile time, but it is a [constant]
* (@ref IOT_MESSAGE_BUFFER_SIZE) that may not be visible to all source files.
* This function allows other source files to know the size of a message buffer.
*
* @return The size, in bytes, of a single message buffer.
*/
/* @[declare_static_memory_messagebuffersize] */
size_t Iot_MessageBufferSize( void );
/* @[declare_static_memory_messagebuffersize] */
/**
* @brief Get an empty message buffer.
*
* This function is the analog of [malloc]
* (http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html)
* for message buffers.
*
* @param[in] size Requested size for a message buffer.
*
* @return Pointer to the start of a message buffer. If the `size` argument is larger
* than the [fixed size of a message buffer](@ref IOT_MESSAGE_BUFFER_SIZE)
* or no message buffers are available, `NULL` is returned.
*/
/* @[declare_static_memory_mallocmessagebuffer] */
void * Iot_MallocMessageBuffer( size_t size );
/* @[declare_static_memory_mallocmessagebuffer] */
/**
* @brief Free an in-use message buffer.
*
* This function is the analog of [free]
* (http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html)
* for message buffers.
*
* @param[in] ptr Pointer to the message buffer to free.
*/
/* @[declare_static_memory_freemessagebuffer] */
void Iot_FreeMessageBuffer( void * ptr );
/* @[declare_static_memory_freemessagebuffer] */
#endif /* if !defined( IOT_STATIC_MEMORY_H_ ) && ( IOT_STATIC_MEMORY_ONLY == 1 ) */
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