On Friday, September 11, 2015 at 14:01, Paul Koning wrote:
> It may be desirable to format or parse values differently for
> different registers. As it stands, that's not possible because the
> function can't tell which register it's formatting. [...]
>
> Ideally one of the argments, for the register case, should point to
> the REG entry for the register in question.
I've run into this same problem with a new simulator I'm developing. I've
solved it (unofficially) by passing a set of user-defined register flags in
the upper 16 bits of the radix parameter, i.e.:
- (fprint_sym (ofile, rdx, &val, NULL, sim_switches | SIM_SW_REG) > 0))
+ (fprint_sym (ofile, (rptr->flags & REG_UFMASK) | rdx, &val,
+ NULL, sim_switches | SIM_SW_REG) > 0))
...and the same for parse_sym. It also needs this in sim_defs.h:
+#define REG_V_UF 16 /* device specific */
+#define REG_UFMASK (~((1u << REG_V_UF) - 1))
I considered passing a register pointer, but this method has two
advantages:
- it's backward compatible, so no changes to calls in existing simulators
are needed
- it allows groups of registers to be handled easily
As an example, I have a "current instruction register" and a "next
instruction register" that both need the same special treatment. I tag
both register definitions with a used-defined REG_IR value, and then in
fprint_sym I need only test for the one flag value rather than two separate
register-pointer values.
I was eventually going to get around to discussing this with Mark :-), but
if you're running into the same problem, perhaps now is a good time. I'm
also not wedded to this approach if there's a cleaner option.
-- Dave
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