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Re: field splitting
- To: Ben Elliston <bje at cygnus dot com>
- Subject: Re: field splitting
- From: Dave Brolley <brolley at redhat dot com>
- Date: Fri, 27 Oct 2000 14:35:27 -0400
- CC: Eric Christopher <echristo at cygnus dot com>, cgen at sources dot redhat dot com
- Organization: Red Hat Canada, Inc
- References: <Pine.LNX.4.21.0010271050080.25402-100000@moshpit.cygnus.com>
Ben Elliston wrote:
> I have an instruction that looks something like this:
> [opcode][4-bits][src][12-bits]
>
> Where the 4 and 12-bit fields are really a part of the same 16-bit
> offset. I've been unable to think of any way to define the field in
> such a way that I can make it a 16-bit operand that just happens to
> contain bits at different spots.
>
> You need to define a multi-ifield, designed explicitly for this purpose.
> Check out the CGEN manual for details.
>
> Ben
fr30.cpu has an example of using a multi ifield.
Dave