heap_5.c
heap5与heap4分配释放算法完全相同，只是heap5支持管理多块不连续的内存，本质是将多块不连续内存用链表串成一整块内存，再用heap4算法来分配释放。若使用heap5则在涉及到分配释放的函数调用时要先调用vPortDefineHeapRegions把多块不连续内存串成一块初始化。
vPortDefineHeapRegions
此函数原型
void vPortDefineHeapRegions( const HeapRegion_t * const pxHeapRegions )，
参数在portable.h中定义，如下
typedef struct HeapRegion
{
uint8_t *pucStartAddress;//指向内存块首地址
size_t xSizeInBytes;//此内存块大小
} HeapRegion_t;
比如有2块内存要用heap5管理，地址0x80000000，大小0x10000,地址0x90000000，大小0xa0000,则如下定义该结构体数组
HeapRegion_t xHeapRegions[] =
{
{ ( uint8_t * ) 0x80000000UL, 0x10000 },
{ ( uint8_t * ) 0x90000000UL, 0xa0000 },
{ NULL, 0 }
};
注意地址顺序要从小到大，最后要以{NULL，0}结尾(源码是以0做判断结束循环)
下面看初始化源码
void vPortDefineHeapRegions( const HeapRegion_t * const pxHeapRegions )
{
BlockLink_t *pxFirstFreeBlockInRegion = NULL, *pxPreviousFreeBlock;
size_t xAlignedHeap;
size_t xTotalRegionSize, xTotalHeapSize = 0;
BaseType_t xDefinedRegions = 0;
size_t xAddress;
const HeapRegion_t *pxHeapRegion;
configASSERT( pxEnd == NULL );
pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );
while( pxHeapRegion->xSizeInBytes > 0 )
{
xTotalRegionSize = pxHeapRegion->xSizeInBytes;
xAddress = ( size_t ) pxHeapRegion->pucStartAddress;
if( ( xAddress & portBYTE_ALIGNMENT_MASK ) != 0 )
{
xAddress += ( portBYTE_ALIGNMENT - 1 );
xAddress &= ~portBYTE_ALIGNMENT_MASK;
xTotalRegionSize -= xAddress - ( size_t ) pxHeapRegion->pucStartAddress;
}
xAlignedHeap = xAddress;
if( xDefinedRegions == 0 )
{
xStart.pxNextFreeBlock = ( BlockLink_t * ) xAlignedHeap;
xStart.xBlockSize = ( size_t ) 0;
}
else
{
configASSERT( pxEnd != NULL );
configASSERT( xAddress > ( size_t ) pxEnd );
}
pxPreviousFreeBlock = pxEnd;
xAddress = xAlignedHeap + xTotalRegionSize;
xAddress -= xHeapStructSize;
xAddress &= ~portBYTE_ALIGNMENT_MASK;
pxEnd = ( BlockLink_t * ) xAddress;
pxEnd->xBlockSize = 0;
pxEnd->pxNextFreeBlock = NULL;
pxFirstFreeBlockInRegion = ( BlockLink_t * ) xAlignedHeap;
pxFirstFreeBlockInRegion->xBlockSize = xAddress - ( size_t ) pxFirstFreeBlockInRegion;
pxFirstFreeBlockInRegion->pxNextFreeBlock = pxEnd;
if( pxPreviousFreeBlock != NULL )
{
pxPreviousFreeBlock->pxNextFreeBlock = pxFirstFreeBlockInRegion;
}
xTotalHeapSize += pxFirstFreeBlockInRegion->xBlockSize;
//下一块
xDefinedRegions++;
pxHeapRegion = &( pxHeapRegions[ xDefinedRegions ] );
}
xMinimumEverFreeBytesRemaining = xTotalHeapSize;
xFreeBytesRemaining = xTotalHeapSize;
configASSERT( xTotalHeapSize );
xBlockAllocatedBit = ( ( size_t ) 1 ) << ( ( sizeof( size_t ) * heapBITS_PER_BYTE ) - 1 );
}常见问题
比如有多块内存，一块是内部ram，其他是外部ram，外部的地址能写死确定，但是内部的会随着程序开发不停改变，怎么确定呢，下面是官网给的例子
#define RAM2_START_ADDRESS ( ( uint8_t * ) 0x00020000 )
#define RAM2_SIZE ( 32 * 1024 )
#define RAM3_START_ADDRESS ( ( uint8_t * ) 0x00030000 )
#define RAM3_SIZE ( 32 * 1024 )
#define RAM1_HEAP_SIZE ( 30 * 1024 )
static uint8_t ucHeap[ RAM1_HEAP_SIZE ];
const HeapRegion_t xHeapRegions[] =
{
{ ucHeap, RAM1_HEAP_SIZE },
{ RAM2_START_ADDRESS, RAM2_SIZE },
{ RAM3_START_ADDRESS, RAM3_SIZE },
{ NULL, 0 }
};
这样就不用老是修改第一块的起始地址。
以上就是FreeRTOS动态内存分配管理heap_5示例的详细内容，更多关于FreeRTOS动态内存分配管理的资料请关注编程网其它相关文章！
