[SOLVED] MemCpy reentrant in different tasks

PeterN · Jan 10th 2022, 10:58am

Dear all,

We divided a piece of ram memory into blocks for reading and writing parameters of several specific tasks. Every task has his block of memory for its parameters.
Is it possible when using Embos that a 'memcp' mess up the data inside a memory block of a task because of interrupting memcpy from one task by another task? Is 'memcpy' reentrant?

Thanks for your support.

Br, Peter

SEGGER - Michael · Jan 10th 2022, 11:36am

Dear Peter,

memcpy() is not part of embOS but is provided by the used C standard library implementation.

Which compiler or C standard library implementation are you using?

If memcpy() should not be thread-safe or reentrant for your C standard library:
Our embOS ports usually support thread-safety if the used compiler and standard library provide the possibility to implement thread-safety.
For further information, please take a look into the chapter "CPU and compiler specifics" of the port specific embOS manual.

Best regards,
Michael Mleczko

PeterN · Jan 10th 2022, 1:42pm

We are using embOS for Cortex-M and SEGGER Embedded Studio version 5.50 on a Nucleo H743Z board from STM
The standard Segger compiler lib for the H7 is used : libc_v7em

Br, Peter

SEGGER - Michael · Jan 10th 2022, 2:02pm

With Embedded Studio, memcpy() is reentrant and thus does not need any further handling to make it thread-safe.
However, if the same memory block is used by multiple tasks, operations on this memory block should still be guarded by mutexes, semaphores or readers-writer locks.

Does this answer your questions?

Please let me know if I can be of any further help.

Best regards,
Michael Mleczko

PeterN · Jan 10th 2022, 3:37pm

Thanks Michael for your help. This is clear for me.

Br,
Peter

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