R1 register reading

[abdelrhman]

Hi all,

How to read or access a general register R1 in MPC5744P micro-controller?
Thanks 

[jiri_kral]

Hi, 

I'm not sure what you mean, but R1 is general purpose register and can be normally used as any other register in assembly code. 

Can you please share more details? 

[abdelrhman]

yes I meant that
but the question
Is there a memory mapped address for register R1 instead of using assembly code for accessing it?

[jiri_kral]

Um, I'm not sure which compiler do you use. This is working only with gcc, not with diab or GHS. 

[jiri_kral]

Hi, 

I see. Yes, you can assign register to a variable like this: 

register int My_C_r1 asm ("r1");

[abdelrhman]

I defined a variable like this but it raises the following error 
expected '=', ',', ';', 'asm' or '__attribute__' before 'asm' 

[jiri_kral]

For reference - here is my test project. 

[jiri_kral]

Can you please share the code snippet with variable definition? For me it is working normally (tested with MPC5744P). 

[abdelrhman]

This is my project 
it is just an example 

[jiri_kral]

this construction can be used with the S32DS default C standard, not with C99. 

Anyway, this technique is almost unusable and deprecated because of optimization. Can you describe in more details what is your goal? 

[abdelrhman]

My goal is to implement a function to monitor the value of R1 register in run time, then import this function to be used in a simulink model.