Generate it with the command

    cat opcodes-v | ./parse-opcodes -vtex

Go has a convention for generated code comments
(https://golang.org/s/generatedcode), i.e. they must match the regex
^// Code generated .* DO NOT EDIT\.$

Adjust the generated header to follow this convention.

Not all systems put Python binary in /usr/bin; fix it as usual by using env(1)

This improves the chance we can use this file with older, pickier
compilers.

Also it makes the OpenOCD patch check script happier.

Closes #17

Now that binutils is upstream, we maintain that file manually.

* Support generating Go code

Generate Go code for the RISC-V Go port
<https://github.com/riscv/riscv-go>.

* Clarify use of yank in Go backend

* Go: Also generate funct3, csr, and funct7 encodings

* Go: Emit all instructions

Changes to the RISC-V Go implementation obviate the need for
GO_UNUSED_INSTRUCTIONS.

* Go: Print CSRs as signed values

* Go: Update parse-opcodes to use obj.As

See https://github.com/golang/go/commit/0d9258a830c585.

* Go: Return errors out of band

* Go: Return 'ok' status instead of 'err' status

Also clean up imports.

* Go: Make gofmt-clean

* Go: Return rs2 value for each instructions

Some binary floating-point instructions (ab)use the rs2 value to hold
additional instruction data, so we need that data in the Go assembler.

It's upstreamed, so avoid the false impression it can easily change.

https://github.com/riscv/riscv-isa-manual/issues/4