Where are the actual RISC-V instruction codes?

Question

I have downloaded the latest...

RISC-V Instruction Set Manual, Volume 1: User-Level ISA

...which is interesting but it never actually gives values for the opcodes/funct3 and other instruction formats. For example, the LOAD/STORE/BRANCH opcodes are listed by name but it does not provide the actual bit values they represent.

Where are all the codes actual listed?

It's actually really irritating. I still don't understand why they didn't just put the value beside the name and be done with it. Not like it's ever going to change. — gonzo, Oct 19 '19 at 06:54

score 7 · Answer 1 · edited Mar 15 '21 at 00:02

7

They are also already conveniently encoded in the source code of the sodor project:

https://github.com/ucb-bar/riscv-sodor

for constants that capture the bit patterns in various useful ways, see:

src/common/instructions.scala

or, directly from the browser:

https://github.com/ucb-bar/riscv-sodor/blob/master/src/main/scala/common/instructions.scala

edited Mar 15 '21 at 00:02

Zbynek Vyskovsky - kvr000

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answered Sep 19 '16 at 12:55

seanhalle

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Looks very useful, many thanks. – Phil Wright Sep 19 '16 at 23:37

score 3 · Accepted Answer · answered Sep 04 '16 at 00:27

3

https://riscv.org/specifications/

Table 9.1 and all of Chapter 9.

answered Sep 04 '16 at 00:27

Chris

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I think you mean Chapter 19. 9 is the double precision floats. – David C. Bishop Aug 20 '17 at 13:25
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Looks like it keeps moving around. In the riscV-spec.pdf "Document Version 20191214-draft" I believe it's now Chapter 26 "RV32/64G Instruction Set Listings" – James May 09 '22 at 23:09

Where are the actual RISC-V instruction codes?

2 Answers2