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FreeRTOS 7.4 :: LPC1768 :: heap_4.c :: prvInsertBlockIntoFreeList :: pxBlockToInsert->xBlockSize

Posted by xdan01 on November 7, 2013

Hello,

i have a question about function

static void prvInsertBlockIntoFreeList(xBlockLink *pxBlockToInsert)

is it possible to be value off pxBlockToInsert->xBlockSize some huge number like 23608965

Is this normal to get in some conditions or this is done by some memory corruption. Device it seems to work on normal after that.

To me it seems is more something gone wrong, but i just want to be sure. I looked some code and i found that maybe could happen on "normal" mode too.

Best regards, Dan


FreeRTOS 7.4 :: LPC1768 :: heap_4.c :: prvInsertBlockIntoFreeList :: pxBlockToInsert->xBlockSize

Posted by richardbarry on November 7, 2013

The top bit of the xBlockSize member is set to indicate the block is owned by the application. When the block is freed the code checks the top bit is set (as part of a sanity check that the block has not already been freed), then the bit is cleared before the block is added back into the free heap.

So, yes, it is expected that the member will contain a huge number while the block is allocated.

Regards.


FreeRTOS 7.4 :: LPC1768 :: heap_4.c :: prvInsertBlockIntoFreeList :: pxBlockToInsert->xBlockSize

Posted by xdan01 on November 7, 2013

Thank you for explanation! Much clearer now!

Thread can be closed now


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