field splitting

[Dave Brolley]

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