twin-butterfly instructions for DCT/FFT save a vast number of instructions for these extremely-common algorithms.
ls016 history: https://git.libre-soc.org/?p=libreriscv.git;a=history;f=openpower/sv/rfc/ls016.mdwn;hb=HEAD twin butterfly history: https://git.libre-soc.org/?p=libreriscv.git;a=history;f=openpower/sv/twin_butterfly.mdwn;hb=HEAD added notes and observations to ls016: https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=daa69e87f5c2455fc7c3bc76e6916abdaf97fde6 add beginnings of english language words to twin_butterfly https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=d5aed1e5d4b45aa909d7aa78e6f50159b2f4ab61
adding c code for core demo of integer DCT twin-butterfly https://git.libre-soc.org/?p=libreriscv.git;a=commitdiff;h=43da45cab9741fbac58918a9ab730aedcf7438bb 8 instructions to be replaced by one, it's a "no contest"