The documentation for 64tass says you're required to pass "--ascii"
when the source file is ASCII (as opposed to PETSCII). We were
ignoring this, but it turns out that everything works a bit better
if we don't.
So we now pass "--ascii" on the command line, and add a two-line
character encoding definition to every file that is generated with
ASCII as the default encoding. The sg_petscii and sg_screen
encodings go away, as PETSCII is now the default, and we can use the
built-in "screen" encoding.
During a discussion with the cc65 developers, I became convinced that
generating "MVN $01,$02" is wrong, and "MVN #$01,#$02" is correct.
64tass, cc65, and Merlin 32 all accept this syntax; only ACME does
not. Operands without a leading '#' should be treated as 24-bit
values, and have the bank byte extracted.
This change updates the on-screen display and assembled output to
include the '#'. The ACME generator uses a Quirk to suppress the
hash mark. (It doesn't currently accept values larger than 8 bits,
so there's no ambiguity.)
The 65816 definition makes it a two-byte instruction, like COP. On
the 6502 it acted like a two-byte instruction, but in practice very
few assemblers treat it that way. Very few humans, for that matter.
So it's now treated as a single byte instruction, with the following
byte encoded as a data value.
Most tests pass, but 2007-labels-and-symbols fails because the
expressions recognized by 64tass don't match up with either of the
other assemblers.
This is currently using a workaround for the local label syntax.
64tass uses '_' as the prefix, which is unfortunate since SourceGen
explicitly allowed underscores in labels. (So does 64tass for that
matter, but it treats labels specially when the '_' comes first.)
We will need to rename any non-local user labels that start with '_'.
(issue #16)
