data alignment

[Elio Fungi]

Which is the data alignment of Labwindows CVI compiler? Byte, word,
double word or quad word? Is there a way to change it?
thanks.

[Chris Matthews]

I believe that CVI is 4 byte aligned by default, but I'm not positive. You can change it though in the same way you would in other C compilers, with a pragma pack statement, i.e.

#pragma pack (1)

would set your alignment to 1 byte. See the National Instruments Knowledgebase here.

Best Regards,

Chris Matthews
National Instruments

[Vishi Anand]

Are you taking about structure alignments? Take a look at pragma directive
in online help.


vishi

"Elio Fungi" wrote in message
news:55dac88b.0302040252.78c519d1@posting.google.com...
> Which is the data alignment of Labwindows CVI compiler? Byte, word,
> double word or quad word? Is there a way to change it?
> thanks.

[msaxon]

The default alignment for CVI is 8 (as reported by the __DEFALIGN macro).

[Kumar_Easwaran]

I found the BOOL type occupies 4bytes instead of one BYTE. Hence declare BYTE in place of BOOL. Other date types does not have any influence.

Chcek the structure size with BYTE instead of BOOL.... You will get what you want 

#pragma pack(push,PLC_TO_HMI,1)//pop,1)//,MyPackedData,1) 

 typedef struct

{

                INT16 ifMachineMode;

                char sMessage[101];

                char sAlaram[101];

                BYTE bfAutoOn;

                BYTE bfAutoDone;

                float LoadArray[10000];

                double DistanceArray[10000];

                float TorqueArray[10000];

                double AngleArray[10000];

                float rfUnlockLoadResult;

                double rfUnlockAngleResult;

                INT16 ifUnlockPlotPoints;

                INT16 ifTiltPlotPoints;

                INT16 ifLockPlotPoints;

                float rfLockLoadResult;

                double rfLockAngleResult;

                double rfSlipDistanceResult;

                float rfTiltLoadResult;

                INT32 ifAdLoad;

                INT32 ifAdTorque;

                BYTE bfPassMsg;

                BYTE bfFailMsg;

                INT16 ifCycleDone;

                INT16 ifOkCount;

                INT16 ifNgCount;

                float rfCycleTime;

                float rfCurrentLoad;

                double rfCurrentDistance;

                float rfCurrentTorque;

                double rfCurrentAngle;

                BYTE Blinker500;

} PLC_TO_HMI;

PLC_TO_HMI Plc2Hmi;