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sean-keys asked on

Assert unique values for a struct member during compile.

I have an embedded application where I need to guarantee that a structure member has a unique value in a table of those structures. I need to ensure that the startingPosition is always unique.

const dataLogDefinition dataLogDefinitions PPAGE_E5 = {
		sizeOfEntry:  sizeof(dataLogField),
		entries: {
				 {.startingPosition = offsetof(CoreVar, IAT), .size = bitSize(CoreVar, IAT), .name = "IAT", .description = "Variable 1", 0,0},
				 {.startingPosition = offsetof(CoreVar, CHT), .size = bitSize(CoreVar, CHT), .name = "CHT", .description = "Variable 2", 0,0},

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Any ideas would be appreciated.
CLinux OS Dev

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Kent Olsen

8/22/2022 - Mon
Kent Olsen

Hi Sean,

Is the table static?  How many items are in the table?  Is uniqueness enough or do they also need to be sequential, non-descending, random, etc.


Yes the table is static. The length will be variable but within reason 20-30 entries. They do not need to be sequential, I just need to make sure something does not end up in there twice.


needs to describe the data here:


The definitions need to remain seperate because they reside in flash while the other resides in RAM, which I have much less of.

Your help has saved me hundreds of hours of internet surfing.
Kent Olsen

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I guess the "right" way to do this would be to have a script generate both C source files. It seems enum, is as good as it gets :)
Kent Olsen

Well, for the specific application that you've shown, I don't think that a random/unique value is sufficient.  I believe that the value is also an index into the array of values returned from the PIC controller.  

You'll want to initialize the value to the correct index value.