topic How could CONST data will not be compiled to be immediate data in code? in S32 Design Studio

How could CONST data will not be compiled to be immediate data in code?

elvan — Tue, 19 Sep 2017 02:46:23 GMT

I am working in a calibration projector. for realtime setting, I don't want that CONST data is compiled to immediate data.

what can I do .

in this case, b = a is compiled to b = 200 in ASM.

C: const u16 a = 200
b = a;

ASM:    14fc: 22c8      movs r2, #200 ; 0xc8
             14fe: 4b04      ldr r3, [pc, #16] ; (1510 <ini_fs_misc+0x24>)
         1500: 801a      strh r2, [r3, #0]

S32DS V1.3 + Win10

Re: How could CONST data will not be compiled to be immediate data in code?

elvan — Tue, 19 Sep 2017 02:53:47 GMT

Developing on the KEAZ128

Re: How could CONST data will not be compiled to be immediate data in code?

stanish — Thu, 21 Sep 2017 09:51:39 GMT

Hi elvan,

One solution could be to declare the const as a volatile. This way you basically disable compiler optimizations for this const.

C: volatile const u16 a = 200

Or access the value of the constant via pointer:

const unsigned short a = 200;
unsigned short *pa = &a;

b=*pa;

Hope it helps.

Re: How could CONST data will not be compiled to be immediate data in code?

elvan — Thu, 21 Sep 2017 19:13:16 GMT

Hi Stanislav.

Thank you very much , it's very useful.