mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
synced 2025-11-04 02:59:01 +01:00
408 lines
17 KiB
C
408 lines
17 KiB
C
/*
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* FreeRTOS Kernel <DEVELOPMENT BRANCH>
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* Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/*
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* A sample implementation of pvPortMalloc() and vPortFree() that permits
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* allocated blocks to be freed, but does not combine adjacent free blocks
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* into a single larger block (and so will fragment memory). See heap_4.c for
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* an equivalent that does combine adjacent blocks into single larger blocks.
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*
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* See heap_1.c, heap_3.c and heap_4.c for alternative implementations, and the
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* memory management pages of https://www.FreeRTOS.org for more information.
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*/
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#include <stdlib.h>
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#include <string.h>
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/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
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* all the API functions to use the MPU wrappers. That should only be done when
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* task.h is included from an application file. */
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#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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#include "FreeRTOS.h"
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#include "task.h"
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#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE
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#if ( configSUPPORT_DYNAMIC_ALLOCATION == 0 )
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#error This file must not be used if configSUPPORT_DYNAMIC_ALLOCATION is 0
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#endif
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#ifndef configHEAP_CLEAR_MEMORY_ON_FREE
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#define configHEAP_CLEAR_MEMORY_ON_FREE 0
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#endif
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/* A few bytes might be lost to byte aligning the heap start address. */
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#define configADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
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/* Assumes 8bit bytes! */
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#define heapBITS_PER_BYTE ( ( size_t ) 8 )
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/* Max value that fits in a size_t type. */
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#define heapSIZE_MAX ( ~( ( size_t ) 0 ) )
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/* Check if multiplying a and b will result in overflow. */
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#define heapMULTIPLY_WILL_OVERFLOW( a, b ) ( ( ( a ) > 0 ) && ( ( b ) > ( heapSIZE_MAX / ( a ) ) ) )
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/* Check if adding a and b will result in overflow. */
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#define heapADD_WILL_OVERFLOW( a, b ) ( ( a ) > ( heapSIZE_MAX - ( b ) ) )
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/* MSB of the xBlockSize member of an BlockLink_t structure is used to track
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* the allocation status of a block. When MSB of the xBlockSize member of
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* an BlockLink_t structure is set then the block belongs to the application.
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* When the bit is free the block is still part of the free heap space. */
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#define heapBLOCK_ALLOCATED_BITMASK ( ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 ) )
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#define heapBLOCK_SIZE_IS_VALID( xBlockSize ) ( ( ( xBlockSize ) & heapBLOCK_ALLOCATED_BITMASK ) == 0 )
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#define heapBLOCK_IS_ALLOCATED( pxBlock ) ( ( ( pxBlock->xBlockSize ) & heapBLOCK_ALLOCATED_BITMASK ) != 0 )
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#define heapALLOCATE_BLOCK( pxBlock ) ( ( pxBlock->xBlockSize ) |= heapBLOCK_ALLOCATED_BITMASK )
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#define heapFREE_BLOCK( pxBlock ) ( ( pxBlock->xBlockSize ) &= ~heapBLOCK_ALLOCATED_BITMASK )
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/*-----------------------------------------------------------*/
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/* Allocate the memory for the heap. */
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#if ( configAPPLICATION_ALLOCATED_HEAP == 1 )
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/* The application writer has already defined the array used for the RTOS
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* heap - probably so it can be placed in a special segment or address. */
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extern uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
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#else
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PRIVILEGED_DATA static uint8_t ucHeap[ configTOTAL_HEAP_SIZE ];
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#endif /* configAPPLICATION_ALLOCATED_HEAP */
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/* Define the linked list structure. This is used to link free blocks in order
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* of their size. */
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typedef struct A_BLOCK_LINK
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{
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struct A_BLOCK_LINK * pxNextFreeBlock; /*<< The next free block in the list. */
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size_t xBlockSize; /*<< The size of the free block. */
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} BlockLink_t;
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static const size_t xHeapStructSize = ( ( sizeof( BlockLink_t ) + ( size_t ) ( portBYTE_ALIGNMENT - 1 ) ) & ~( ( size_t ) portBYTE_ALIGNMENT_MASK ) );
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#define heapMINIMUM_BLOCK_SIZE ( ( size_t ) ( xHeapStructSize * 2 ) )
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/* Create a couple of list links to mark the start and end of the list. */
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PRIVILEGED_DATA static BlockLink_t xStart, xEnd;
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/* Keeps track of the number of free bytes remaining, but says nothing about
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* fragmentation. */
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PRIVILEGED_DATA static size_t xFreeBytesRemaining = configADJUSTED_HEAP_SIZE;
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/* Indicates whether the heap has been initialised or not. */
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PRIVILEGED_DATA static BaseType_t xHeapHasBeenInitialised = pdFALSE;
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/*-----------------------------------------------------------*/
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/*
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* Initialises the heap structures before their first use.
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*/
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static void prvHeapInit( void ) PRIVILEGED_FUNCTION;
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/*-----------------------------------------------------------*/
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/* STATIC FUNCTIONS ARE DEFINED AS MACROS TO MINIMIZE THE FUNCTION CALL DEPTH. */
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/*
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* Insert a block into the list of free blocks - which is ordered by size of
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* the block. Small blocks at the start of the list and large blocks at the end
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* of the list.
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*/
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#define prvInsertBlockIntoFreeList( pxBlockToInsert ) \
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{ \
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BlockLink_t * pxIterator; \
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size_t xBlockSize; \
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\
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xBlockSize = pxBlockToInsert->xBlockSize; \
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\
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/* Iterate through the list until a block is found that has a larger size */ \
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/* than the block we are inserting. */ \
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for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize; pxIterator = pxIterator->pxNextFreeBlock ) \
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{ \
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/* There is nothing to do here - just iterate to the correct position. */ \
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} \
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\
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/* Update the list to include the block being inserted in the correct */ \
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/* position. */ \
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pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock; \
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pxIterator->pxNextFreeBlock = pxBlockToInsert; \
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}
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/*-----------------------------------------------------------*/
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void * pvPortMalloc( size_t xWantedSize )
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{
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BlockLink_t * pxBlock;
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BlockLink_t * pxPreviousBlock;
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BlockLink_t * pxNewBlockLink;
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void * pvReturn = NULL;
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size_t xAdditionalRequiredSize;
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size_t xAllocatedBlockSize = 0;
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if( xWantedSize > 0 )
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{
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/* The wanted size must be increased so it can contain a BlockLink_t
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* structure in addition to the requested amount of bytes. */
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if( heapADD_WILL_OVERFLOW( xWantedSize, xHeapStructSize ) == 0 )
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{
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xWantedSize += xHeapStructSize;
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/* Ensure that blocks are always aligned to the required number
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* of bytes. */
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if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
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{
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/* Byte alignment required. */
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xAdditionalRequiredSize = portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK );
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if( heapADD_WILL_OVERFLOW( xWantedSize, xAdditionalRequiredSize ) == 0 )
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{
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xWantedSize += xAdditionalRequiredSize;
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}
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else
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{
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xWantedSize = 0;
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}
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}
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else
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{
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mtCOVERAGE_TEST_MARKER();
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}
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}
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else
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{
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xWantedSize = 0;
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}
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}
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else
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{
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mtCOVERAGE_TEST_MARKER();
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}
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vTaskSuspendAll();
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{
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/* If this is the first call to malloc then the heap will require
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* initialisation to setup the list of free blocks. */
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if( xHeapHasBeenInitialised == pdFALSE )
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{
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prvHeapInit();
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xHeapHasBeenInitialised = pdTRUE;
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}
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/* Check the block size we are trying to allocate is not so large that the
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* top bit is set. The top bit of the block size member of the BlockLink_t
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* structure is used to determine who owns the block - the application or
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* the kernel, so it must be free. */
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if( heapBLOCK_SIZE_IS_VALID( xWantedSize ) != 0 )
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{
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if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) )
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{
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/* Blocks are stored in byte order - traverse the list from the start
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* (smallest) block until one of adequate size is found. */
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pxPreviousBlock = &xStart;
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pxBlock = xStart.pxNextFreeBlock;
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while( ( pxBlock->xBlockSize < xWantedSize ) && ( pxBlock->pxNextFreeBlock != NULL ) )
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{
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pxPreviousBlock = pxBlock;
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pxBlock = pxBlock->pxNextFreeBlock;
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}
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/* If we found the end marker then a block of adequate size was not found. */
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if( pxBlock != &xEnd )
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{
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/* Return the memory space - jumping over the BlockLink_t structure
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* at its start. */
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pvReturn = ( void * ) ( ( ( uint8_t * ) pxPreviousBlock->pxNextFreeBlock ) + xHeapStructSize );
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/* This block is being returned for use so must be taken out of the
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* list of free blocks. */
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pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;
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/* If the block is larger than required it can be split into two. */
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if( ( pxBlock->xBlockSize - xWantedSize ) > heapMINIMUM_BLOCK_SIZE )
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{
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/* This block is to be split into two. Create a new block
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* following the number of bytes requested. The void cast is
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* used to prevent byte alignment warnings from the compiler. */
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pxNewBlockLink = ( void * ) ( ( ( uint8_t * ) pxBlock ) + xWantedSize );
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/* Calculate the sizes of two blocks split from the single
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* block. */
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pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
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pxBlock->xBlockSize = xWantedSize;
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/* Insert the new block into the list of free blocks.
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* The list of free blocks is sorted by their size, we have to
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* iterate to find the right place to insert new block. */
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prvInsertBlockIntoFreeList( ( pxNewBlockLink ) );
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}
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xFreeBytesRemaining -= pxBlock->xBlockSize;
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xAllocatedBlockSize = pxBlock->xBlockSize;
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/* The block is being returned - it is allocated and owned
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* by the application and has no "next" block. */
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heapALLOCATE_BLOCK( pxBlock );
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pxBlock->pxNextFreeBlock = NULL;
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}
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}
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}
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traceMALLOC( pvReturn, xAllocatedBlockSize );
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/* Prevent compiler warnings when trace macros are not used. */
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( void ) xAllocatedBlockSize;
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}
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( void ) xTaskResumeAll();
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#if ( configUSE_MALLOC_FAILED_HOOK == 1 )
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{
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if( pvReturn == NULL )
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{
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vApplicationMallocFailedHook();
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}
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}
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#endif
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return pvReturn;
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}
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/*-----------------------------------------------------------*/
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void vPortFree( void * pv )
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{
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uint8_t * puc = ( uint8_t * ) pv;
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BlockLink_t * pxLink;
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if( pv != NULL )
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{
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/* The memory being freed will have an BlockLink_t structure immediately
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* before it. */
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puc -= xHeapStructSize;
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/* This unexpected casting is to keep some compilers from issuing
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* byte alignment warnings. */
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pxLink = ( void * ) puc;
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configASSERT( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 );
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configASSERT( pxLink->pxNextFreeBlock == NULL );
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if( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 )
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{
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if( pxLink->pxNextFreeBlock == NULL )
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{
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/* The block is being returned to the heap - it is no longer
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* allocated. */
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heapFREE_BLOCK( pxLink );
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#if ( configHEAP_CLEAR_MEMORY_ON_FREE == 1 )
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{
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( void ) memset( puc + xHeapStructSize, 0, pxLink->xBlockSize - xHeapStructSize );
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}
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#endif
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vTaskSuspendAll();
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{
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/* Add this block to the list of free blocks. */
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prvInsertBlockIntoFreeList( ( ( BlockLink_t * ) pxLink ) );
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xFreeBytesRemaining += pxLink->xBlockSize;
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traceFREE( pv, pxLink->xBlockSize );
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}
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( void ) xTaskResumeAll();
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}
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}
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}
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}
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/*-----------------------------------------------------------*/
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size_t xPortGetFreeHeapSize( void )
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{
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return xFreeBytesRemaining;
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}
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/*-----------------------------------------------------------*/
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void vPortInitialiseBlocks( void )
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{
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/* This just exists to keep the linker quiet. */
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}
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/*-----------------------------------------------------------*/
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void * pvPortCalloc( size_t xNum,
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size_t xSize )
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{
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void * pv = NULL;
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if( heapMULTIPLY_WILL_OVERFLOW( xNum, xSize ) == 0 )
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{
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pv = pvPortMalloc( xNum * xSize );
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if( pv != NULL )
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{
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( void ) memset( pv, 0, xNum * xSize );
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}
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}
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return pv;
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}
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/*-----------------------------------------------------------*/
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static void prvHeapInit( void ) /* PRIVILEGED_FUNCTION */
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{
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BlockLink_t * pxFirstFreeBlock;
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uint8_t * pucAlignedHeap;
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/* Ensure the heap starts on a correctly aligned boundary. */
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pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT - 1 ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );
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/* xStart is used to hold a pointer to the first item in the list of free
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* blocks. The void cast is used to prevent compiler warnings. */
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xStart.pxNextFreeBlock = ( void * ) pucAlignedHeap;
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xStart.xBlockSize = ( size_t ) 0;
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/* xEnd is used to mark the end of the list of free blocks. */
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xEnd.xBlockSize = configADJUSTED_HEAP_SIZE;
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xEnd.pxNextFreeBlock = NULL;
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/* To start with there is a single free block that is sized to take up the
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* entire heap space. */
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pxFirstFreeBlock = ( BlockLink_t * ) pucAlignedHeap;
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pxFirstFreeBlock->xBlockSize = configADJUSTED_HEAP_SIZE;
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pxFirstFreeBlock->pxNextFreeBlock = &xEnd;
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}
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/*-----------------------------------------------------------*/
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/*
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* Reset the state in this file. This state is normally initialized at start up.
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* This function must be called by the application before restarting the
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* scheduler.
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*/
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void vPortHeapResetState( void )
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{
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xFreeBytesRemaining = configADJUSTED_HEAP_SIZE;
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xHeapHasBeenInitialised = pdFALSE;
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}
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/*-----------------------------------------------------------*/
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