Digital Signal ControllersのトピックRe: Force variables alignment in MC56F8XXXX DSC

Force variables alignment in MC56F8XXXX DSC

cabl — Tue, 29 Apr 2014 13:30:10 GMT

Hi there,

How could one easily force alignment of variables in code (avoiding creation of specific section in linker files, and explicit placement via OBJECT)? Something similar to the #pragma pack present in other micros.

Thanks.

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Hola,

¿Cómo se puede fozar fácilmente la alineación de variables desde el código (evitando crear secciones nuevas en el fichero del linker y evitando tener que colocar cada variable con OBJECT)? Algo parecido a #pragma pack existente para otros micros.

Gracias.

Re: Force variables alignment in MC56F8XXXX DSC

Ben — Fri, 02 May 2014 18:23:23 GMT

I think that the ALIGN command will do what you need. See ALIGN and ALIGNALL in the ELF linker file issue.

Re: Force variables alignment in MC56F8XXXX DSC

cabl — Fri, 09 May 2014 06:09:22 GMT

Hi Ben,

thanks for your answer.

However, as far as I know, ALIGN is for the linker file, not for the code (*.c) file. I´m looking for a more flexible way that doesn´t imply changing linker file.

Best regards,

Re: Force variables alignment in MC56F8XXXX DSC

Ben — Mon, 12 May 2014 13:58:02 GMT

Hi Carios

Thats correct, but you can add once to the linker file a section with ALIGNALL definition, and in the code putting the variables you want to align in this section.

The problem I have with the alignment is that you can not align data to 1 byte long, the minimum is 2 bytes. in data communication I need 1 byte too

Re: Force variables alignment in MC56F8XXXX DSC

Ben — Thu, 15 May 2014 16:54:28 GMT

Hi Carlos

Good news. I found out that one of our customers is doing exactly what you need.

The "trick" he used is adding attribute to variable definition. For example:

char test[6] __attribute__((aligned(2)));

I did not try it yet.

If someone of CW staff watching this place, please comment. I saw no CW documentation for using attributes in code, only for LCF

I hope it helps

Re: Force variables alignment in MC56F8XXXX DSC

cabl — Tue, 07 Apr 2015 08:00:49 GMT

Hi Ben,

thank you for the info. I´ve found that from CW10.6 on it´s possible to do __attribute__((aligned(2))), though it seems that __attribute__((aligned(1))) is not working.

Regards