Document the named field syntax that we want to implement for the
decodetree script. This allows a field to be defined in terms of
some other field that the instruction pattern has already set, for
example:
%sz_imm 10:3 sz:3 !function=expand_sz_imm
to allow a function to be passed both an immediate field from the
instruction and also a sz value which might have been specified by
the instruction pattern directly (sz=1, etc) rather than being a
simple field within the instruction.
Note that the restriction on not having the format referring to the
pattern and the pattern referring to the format simultaneously is a
restriction of the decoder generator rather than inherently being a
silly thing to do.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230523120447.728365-3-peter.maydell@linaro.org>
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