In the RISCV ISA I dont see any bit manipulation instructions. E.g., clearing a bit cannot be done with a single instruction and currently would require more than one instruction to create a mask and then 'and' it. Is it being thought of or is there no plan to introduce such instructions. Just trying to understand the rationale behind not having such instructions.In embedded applications usually there are many bit manipulation code. Not having such instruction may increase the code size considerably. On the mailing list archives I saw some old discussions on bit manipulation instructions. Is it being actively pursued? Does that mean RISCV is not widely being used in embedded space as of now(where code density also matters)?
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Yes, there are plans to add bit manipulation instructions.At the moment the best resource for possible instructions is probably https://github.com/cliffordwolf/xbitmanip
On Tue, Jun 26, 2018 at 9:01 PM, Gnanasekar R <gnanase...@gmail.com> wrote:
In the RISCV ISA I dont see any bit manipulation instructions. E.g., clearing a bit cannot be done with a single instruction and currently would require more than one instruction to create a mask and then 'and' it. Is it being thought of or is there no plan to introduce such instructions. Just trying to understand the rationale behind not having such instructions.In embedded applications usually there are many bit manipulation code. Not having such instruction may increase the code size considerably. On the mailing list archives I saw some old discussions on bit manipulation instructions. Is it being actively pursued? Does that mean RISCV is not widely being used in embedded space as of now(where code density also matters)?
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In the RISCV ISA I dont see any bit manipulation instructions. E.g., clearing a bit cannot be done with a single instruction and currently would require more than one instruction to create a mask and then 'and' it. Is it being thought of or is there no plan to introduce such instructions. Just trying to understand the rationale behind not having such instructions.In embedded applications usually there are many bit manipulation code. Not having such instruction may increase the code size considerably. On the mailing list archives I saw some old discussions on bit manipulation instructions. Is it being actively pursued? Does that mean RISCV is not widely being used in embedded space as of now(where code density also matters)?
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(or one if it's in the lowest 12 bits), and clearing a bit with three instructions (or one if it's in the lowest 12 bits).
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