> Right now I can't find a good way to test a bit in a variable such
> that it is assured to compile down to using the bit test instructions.

> All I could find that is close is this but it does not seem to return
> the bit's value.  Is it returning an address?  Do I need to
> dereference it in use?
>
> #define PORTBIT(adr, bit)  ((unsigned)(&adr)*8+(bit))

Yes. It's converting to an address. You can then use that to
declare a bit variable at that address. Examples -

static volatile bit     SR_OE           PORT_BIT(PORTC, 2);
static volatile bit     SR_Strobe       PORT_BIT(PORTC, 5);
static volatile bit     SR_DatPin       PORT_BIT(PORTC, 4);
static volatile bit     SR_ClkPin       PORT_BIT(PORTC, 3);

Steve.

======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: steveb@tla.co.nz      fax +64 9 820-1929
======================================================

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