Error due to GNU ARM toolchain usage in IAR workbench

armiarstm32f4

I recently started programming with STM32F4Discovery board and am using IAR workbench as the IDE. I am supposed to use an already developed program in Eclipse as a part of my project. When I imported this into IAR Workbench, I get the following error and warnings:
Error[Pe020]: identifier "_impure_ptr" is undefined
Warning[Pe223]: function "_REENT_INIT_PTR" declared implicitly
Warning[Pe223]: function "_reclaim_reent" declared implicitly C

I have realized that the _impure_ptr, _REENT_INIT_PTR, _reclaim_reent are a part of the reent.h file which are present in the GNU ARM Toolchain. This is being used as a part of the using FreeRTOS functionality. With Eclipse, this is not a problem, but when using IAR workbench, is there any other file similar to the reent.h for IAR Workbench that I am supposed to include?

I know it is a naive question but I am a beginner to embedded programming and still in the initial stages of setting up this project.

Best Answer

The global variable _impure_ptr is part of newlib libc as used by the GNU ARM Toolchain. IAR uses, as far as I can tell, it's own implementation of the standard C library called CLIB.

The standard C library usually contains all/most function defined in the C standard. As far as these function (printf, strlen...) go, the two libraries should be rather compatible. In other areas these libraries tend to differ. The variable _impure_ptr is used by newlib to support multi threading and contains all global variables used by that thread (e.g. errno).

FreeRTOS has builtin support for newlib reentrancy (although not officially supported by the developers). If this is activated, FreeRTOS keeps a copy of this reentrancy context for every task and replaces the global variable on context switch. You can disable this in your FreeRTOSConfig.h, by setting configUSE_NEWLIB_REENTRANT to 0. But make sure that the IAR libc is reentrant, otherwise you might get into trouble later on.

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