Re: Custom FP sqrt function

Altera_Forum · ‎08-05-2015

Hi,

The Nios compiler doesn't seem to recognize the -mcustom-fsqrts option.

I've tried sqrt and sqrtf.

I noticed on this page:

http://www.alterawiki.com/wiki/single-precision_-mcustom-*_options

that the gcc pattern name is listed as sqrtsf2

but that is not the case for the libm function.

Any suggestions?

Thanks,

Jonah

Altera_Forum · ‎10-02-2015

I assume you have connected the floating point custom instruction hardware (FPH2) to the custom instruction port of the Nios?

The sqrtf function is not directly inferred. You will need to explicitly include the headers into your C code.

# include "altera_nios_custom_instr_floating_point_2.h"

Then you can use sqrtf function normally. You should always include the headers when using the FPH2 module. Also you can check from objdump to re-confirm on the custom instructions being called.