"PACKED" compiler directive - c2000

Hello,

I'll move your post to the Compilers Forum for better support.

Elizabeth

Raghu Rajappa said:

Is there a non-manual workaround for "PACKED" in c2000 compiler?

Unfortunately, no.

Thanks and regards,

-George

Thank you George.

Ok, Manually I plan to use bitfields. Example code shown below.

typedef struct CC_PACKED
{
   INT16U PSA;
   INT16U Length;

#if defined(EC_LITTLE_ENDIAN)
   INT8U Mode:2;
   INT8U Direction:2;
   INT8U IntECAT:1;
   INT8U IntPDI:1;
   INT8U WTE:1;
   INT8U R1:1;

   INT8U IntW:1;
   INT8U IntR:1;
   INT8U R2:1;
   INT8U MBXstat:1;
   INT8U BUFstat:2;
   INT8U R3:2;

   INT8U ECsm:1;
   INT8U ECrep:1;
   INT8U ECr4:4;
   INT8U EClatchEC:1;
   INT8U EClatchPDI:1;

   INT8U PDIsm:1;
   INT8U PDIrep:1;
   INT8U PDIr5:6;
#endif

} _ESCsm;

The problem occurs when I have to use arrays in the structure (bitfield on array is not possible is my understanding - please correct me if I am wrong) 

typedef struct CC_PACKED
{
   _MBXh header;
   INT8U b[MBXDSIZE];
} _MBX;

Since my controller is 16 bit, and the array (b) is 8 bit array of size MBXDSIZE, it will look like this inside the memory

ADDRESS X ->        b[0], padded byte
ADDRESS X + 1 -> b[1], padded byte
ADDRESS X + 2 -> b[2], padded byte
....

I am not so sure how to make a workaround for this. Any help would be appreciated. The intention is to keep the code as simple as possible while getting rid of padding when PACKED is not supported... Also please correct my understanding if needed.

It's not possible on C28x to have an array of 8-bit objects because each array element must be at least one addressable unit (16 bits) in size, even when using packed.

Perhaps you could make use of the __byte instrinsic:
__byte(b, 0) /* 1st 8 bits of array b */
__byte(b, 1) /* 2nd 8 bits of array b */
__byte(b, 2) /* 3rd 8 bits of array b */