Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem TCP & FAT


Extra bytes in heapSTRUCT_SIZE?

Posted by Tom Daugherty on October 9, 2012
Using v7.2.0, it looks like there are an extra 8 bytes added for every pvPortMalloc call due to the computation of heapSTRUCT_SIZE. This is true for heap_2 and heap_4. Currently,

static const unsigned short heapSTRUCT_SIZE= ( sizeof( xBlockLink ) + portBYTE_ALIGNMENT - ( sizeof( xBlockLink ) % portBYTE_ALIGNMENT ) );

and in my case of a Cortex-M4 and a Keil compiler, portBYTE_ALIGNMENT is 8, and sizeof(xBlockLink) is 8. This line of code results in a heapSTRUCT_SIZE of 16 when the actual structure size is already on an 8 byte boundary. Would it be better to do something like,

static const unsigned short heapSTRUCT_SIZE = (sizeof(xBlockLink) & portBYTE_ALIGNMENT_MASK)?
(sizeof(xBlockLink) + (portBYTE_ALIGNMENT - (sizeof(xBlockLink) & portBYTE_ALIGNMENT_MASK))):

[ Back to the top ]    [ About FreeRTOS ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

FreeRTOS kernel V10 is available for immediate download. Now MIT licensed.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS