openhwgroup / core-v-xif

RISC-V eXtension interface that provides a generalized framework suitable to implement custom coprocessors and ISA extensions
https://docs.openhwgroup.org/projects/openhw-group-core-v-xif/en
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[Review Comment]: Clarify description of encoding space for RS3 #223

Closed Gchauvon closed 5 months ago

Gchauvon commented 5 months ago

Comment

I believe there is a typo in the description of the encoding space for rs3 in [31:27] only for R4-type instructions.

Proposed Resolution

https://github.com/openhwgroup/core-v-xif/blob/bdf5f1c89313dac1cf21160f1b84fa9f43becccf/docs/source/x_ext.rst?plain=1#L259

I propose :

If an offloaded instruction uses the register file source rs3, then these are encoded in instruction bits [31:27] if the instruction uses the major opcodes MADD, MSUB, NMSUB, or NMADD (R4-type).

Addition Info

No response