Why I am not able to build the CRC Nios II custom instruction example?

Description

When using the CRC Nios^® II custom instruction example in https://www.altera.com/support/support-resources/design-examples/intellectual-property/embedded/nios-ii/exm-custom-instruction.html in 17.1

there is a compiler error of undefined reference to ALT_CI_CRC_0_N.

Resolution

To fix this issue, the ALT_CI_CRC_0_N variable name in ci_crc.c need to be changed to ALT_CI_CRC_CUSTOM_INSTRUCTION_0_N.

This is due to the earlier name set for the Nios^® II custom instruction component, as stated in Step 2. page 30 from this document;

https://www.altera.com/en_US/pdfs/literature/ug/ug_nios2_custom_instruction.pdf

A future fix will be applied on the software code files in coming 18.1