FPGA difference between pack cluster vs unpack cluster

[cshim31]

Hello Community, 

I used FPGA C API generator to export a header file, but it didn't show any message about the function called

(FPGA VI NAME)_IndiciatorCluster_UnpackCluster

(FPGA VI NAME)_IndiciatorCluster_PackCluster

what would those functions do and how would they be different?

[Michael_Strain · Accepted solution]

When a cluster is instantiated on the FPGA it is "packed".  There are no padding bits because alignment doesn't matter on the FPGA.

We choose to represent clusters in C as structs.  Structs are padded and alignment of members can differ on different architectures.

The unpack and pack functions let you convert between the FPGA representation and the C representation.  When reading a cluster indicator from the FPGA you'll read it as the FPGA representation and convert it to a C struct to access the data in it.

C -> packCluster -> FPGA 

FPGA -> unpackCluster -> C