This is the RISC-V XBitmanip Extension draft spec. The spec aims to extend the RISC-V instruction set to enable efficent bit manipulation. This includes operations like;
- counting bits, leading zeros, etc
- bit extraction
- rotations, shifting and reversing
Originally it was the B-Extension draft spec, but the work group got dissolved for burocratic reasons in November 2017.
It is currently an independently maintained document. We'd happily donate it to the RISC-V foundation as starting point for a new B-Extension work group, if there will be one.
See xbitmanip-draft.pdf for a pre-built version of the PDF spec document.
There is also a riscv-xbitmanip google group.
Building this document from the LaTeX source:
bash xbitmanip.sh 5