Previously, we used the default character encoding from the project
properties to determine how strings and character constants in the
entire source file should be encoded. Now we switch between
encodings as needed. The default character encoding is no longer
relevant.
High ASCII is now an actual encoding, rather than acting like ASCII
that sometimes doesn't work. Because we can do high ASCII character
operands with "| $80", we don't output a .enc to switch from ASCII
to high ASCII unless we need to generate a string. (If we're
already in high ASCII mode, the "| $80" isn't required but won't
hurt anything.)
We now do a scan up front to see if ASCII or high ASCII is needed,
and only output the .cdefs for the encodings that are actually used.
The only gap in the matrix is high ASCII DCI strings -- the ".shift"
pseudo-op rejects text if the string doesn't start with the high
bit clear.
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.
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)
