gnupic@linuxhacker.org

I probably should've sent this just to Craig, but maybe someone else has 
an answer.

I was dabbling around in SDCC trying to figure out why bit variables are
no longer working. One of the problems is that if an 'EQU' directive
contains an expression with a reference to a relocatable object, then the
'first-pass' value is used for the relocatable object when the EQU is
evaluated. I'm not sure if that sentence makes sense, so here's an 
example:


bitfield1	res	1

_bit0	EQU	( (bitfield0<<3)+0)
_bit1	EQU	( (bitfield0<<3)+1)
_bit2	EQU	( (bitfield0<<3)+2)


The idea is that an array of named bits is created and aliased onto the 
byte reserved by the bitfield.


Now, if you write code to access the bits:

    bcf   _bit0 >> 3, _bit0 & 7

gpasm fails to assemble it correctly. The relocatable address used to
evaluate the EQU expressions is not correct.

I suspect this is not easy to fix in gpasm. I do not know if this 
construct works with MPASM (I don't have convenient access to a Window's 
machine with MPLAB installed).

I've used this technique many times for creating bit fields in
absolute-mode code. Does anyone know of a good way of creating bitfields
in relocatable code?

Scott