Packed structs in CCE

Jomar Hønsi

Hi,

I have just started playing with CCE 3.0 and have a question regarding packing of C-language structures.

With IAR we use the pragma below to pack a structure, what would the equivalent be using CCE? Without the default settings, CCE insert padding bytes before the 8-bit variables, I want to avoid this.

#ifdef __ICC430__

#pragma pack(1)

#endif

typedef struct {

uint8 packetLength;

uint16 frameControlField;

uint8 seqNumber;

uint16 panId;

uint16 destAddr;

uint16 srcAddr;

#ifdef SECURITY_CCM

uint8 securityControl;

uint32 frameCounter;

#endif

} basicRfPktHdr_t;

#ifdef __ICC430__

#pragma pack()

#endif

over 17 years ago

0 Antonio Espirito-Santo over 17 years ago

Expert 2855 points

Searching the MSP430 Optimizing C/C++ Compiler User's Guide I do not find any reference to the pragma pack directive. So, I think it is not supported (is this true?!)

I also like to know how to pack a structure with CCE.

Searching the web I find this nice article.

AES

0 Antonio Espirito-Santo over 17 years ago in reply to Antonio Espirito-Santo

Expert 2855 points

After reading the previously article I search and find that we can enable the –gcc compiler option. This option allows us to use the GNU C Compiler Extensions, like specify the attributes of variables. Here you can find useful information about this subject.

So, after you active the –gcc option (in Properties > C/C++ Build > MSP430 Compiler 3.0 > Runtime Model Option) you will be allowed to make declarations like

int x __attribute__ ((aligned (16))) = 0;

short array[3] __attribute__ ((aligned));

Unfortunately, when I try to use the packed keyword compiler tells me that this is an invalid attribute for field.

AES

0 AartiG over 17 years ago in reply to Antonio Espirito-Santo

TI__Guru**** 173310 points

The TI compilers including the MSP430 compiler in CCE do not support packed structures.
https://community.ti.com/forums/p/87/119.aspx#119

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Packed structs in CCE