Add a custom instruction with only one input - BSP auto generated

Question

I've just created a custom instruction in Qsys that uses only one input. There is only dataa[] in the interface.

However the Eclipse generates a instruction with 2 operands.

#define ALT_CI_WELLPRNG_0(A,B) __builtin_custom_inii(ALT_CI_WELLPRNG_0_N,(A),(B))

Did I do anything wrong? Or should I always fix that by hand?

Thank you.

altera_forum · Answer

For your Qsys component, did you set the 'operands' parameter of the custom instruction interface to the value of '1' ?  By default, it is set to '2'.

altera_forum · Answer

Thank you ted.

I didn´t notice the fild when building it.

And since you are here.

I´m preaty sure my instruction takes only one cicle to execute. But I can´t change the field to "Combinational" only "Variable".

altera_forum · Answer

https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/ug/ug_nios2_custom_instruction.pdf

Does your interface described in your _hw.tcl look like Figure 3, or Figure 5 ? Try removing extra signals if it looks like Figure 5.

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Add a custom instruction with only one input - BSP auto generated

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