[cc65] Expression usage question

I'm going to make a somewhat incompatible change to the assembler, and would
like to hear about current usage to make the change less intrusive.

Currently, all expressions are evaluated using (at least) 32 bit values within
the assembler. Exported symbols are truncated to 32 bits. One problem that
proved to be serious in some cases is that the assembler doesn't have a clear
notation of signedness: Symbol values are handled as signed or unsigned values
depending on the context. An example is

        foo = -1

        lda     #foo            ; Error: Out of range

Since the internal representation of foo is $FFFFFFFF, and since the lda
instruction expects an 8 bit operand, the assembler would output an error.

My plan is to resolve these ambiguities by explicitly defining numeric values
to be always 32 bit signed. Neither the 6502 nor the 816 can handle 32 bit
values, so most programs don't use values where bit 31 is used as a value bit
(and not as a sign bit). In addition, it would still be possible to do
something like

        foo = $FFFFFFFF

but internally foo would be represented as -1. It is also possible for the
code written, to handle such values as unsigned, but again, the assembler
itself will always handle them as signed values.

An operator that will change its meaning in the transition is the shift
operator. Shifts are currently unsigned. That is,

        $FFFFFFFF >> 1 = $7FFFFFFF

This will change, but new unsigned shift operators will be made available.

There may be other, less obvious problems.

While the change would not affect most programs, there may be some that run
into problems. So I would like to evaluate how many such programs exist, and
if there is something I can do to ease the transition. If you have written
code that depends on the current interpretation of 32 bit values, please let
me know.

Happy easter!


        Uz


-- 
Ullrich von Bassewitz                                  uz@musoftware.de
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