Sometimes it's useful to know whether an address referenced by a
function is a direct access, or is being used as a base address.
(I'm somewhat undecided on this one, since it clutters up the list
a bit. Giving it a try.)
The code was making an unwarranted assumption about how the flags
were being set. For example, ORA #$00 can't know if the previous
contents of the accumulator were nonzero, only that the instruction
hasn't made them nonzero, but instead of marking the Z-flag
"indeterminate" it was leaving the flag in its previous state. This
produces incorrect results if the previous instruction didn't set
its flags from the accumulator contents, e.g. it was an LDX.
Test 1003-flags-and-branches has been updated to test these states.
For nonzero values we were leaving Z=prev, which is wrong when Z=0
because the AND result might be zero. Now if Z=1 we leave it alone,
but if Z=0 we now set it to Z=?.
Test 1003-flags-and-branches was testing for the (incorrect)
behavior, so we're now running into a BRK. This is fine.
The "affected flags" constants were incorrect for BIT, BRK, COP,
RTI, XCE, and the undocmented instructions ANE, DCP, and SAX. The
constants are used for the changed-flag summary shown in the info
window and the instruction chart.
Of greater import: the status flag updater for BIT was incorrectly
marking N/V/C as indeterminate instead of N/V/Z. The undocmented
instructions ANE, DCP, and SAX were also incorrect.
The cycle counts shown in line comments are computed correctly, but
the counts shown in the info window and instruction chart were
displaying the full set of modifiers, ignoring the CPU type. That's
okay for the info window, which spells the modifiers out, though
it'd be better if the bits were explicitly marked as being applicable
to the current CPU or a different one.
Sort of silly to have every handler immediately pull the operand out
of the file data. (This is arguably less efficient, since we now
have to serialize the argument across the AppDomain boundary, but
we should be okay spending a few extra nanoseconds here.)
Memory-mapped I/O locations can have different behavior when read
vs. written. This is part 1 of a change to allow two different
symbols to represent the same address, based on I/O direction.
This also adds a set of address masks for systems like the Atari
2600 that map hardware addresses to multiple locations.
This change updates the data structures, .sym65 file reader,
project serialization, and DefSymbol editor.
Early data sheets listed BRK as one byte, but RTI after a BRK skips
the following byte, effectively making BRK a 2-byte instruction.
Sometimes, such as when diassembling Apple /// SOS code, it's handy
to treat it that way explicitly.
This change makes two-byte BRKs optional, controlled by a checkbox
in the project settings. In the system definitions it defaults to
true for Apple ///, false for all others.
ACME doesn't allow BRK to have an arg, and cc65 only allows it for
65816 code (?), so it's emitted as a hex blob for those assemblers.
Anyone wishing to target those assemblers should stick to 1-byte mode.
Extension scripts have to switch between formatting one byte of
inline data and formatting an instruction with a one-byte operand.
A helper function has been added to the plugin Util class.
To get some regression test coverage, 2022-extension-scripts has
been configured to use two-byte BRK.
Also, added/corrected some SOS constants.
See also issue #44.
If you set things up just right, it's possible for flag status
changes to fail to get merged.
Added a regression test to 1003-flags-and-branches.
Also, tweaked the instruction operand editor to be a bit smoother
from the keyboard: added alt-key shortcuts, and put the focus on the
OK button after creating/editing a label so you can just hit the
return key twice.
Cycle counting is CPU-specific. The 2020 test exercises the
65816, but there are things unique to 6502 and 65C02 that should
also be checked if we want to be thorough.
No changes to the test itself.
Implemented local variable editing. Operands that have a local
variable reference, or are eligible to have one, can now be edited
directly from the instruction operand edit dialog.
Also, updated the code list double-click handler so that, if you
double-click on the opcode of an instruction that uses a local
variable reference, the selection and view will jump to the place
where that variable was defined.
Also, tweaked the way the References window refers to references
to an address that didn't use a symbol at that address. Updated
the explanation in the manual, which was a bit confusing.
Also, fixed some odds and ends in the manual.
Also, fixed a nasty infinite recursion bug (issue #47).
Variables are now handled properly end-to-end, except for label
uniquification. So cc65 and ACME can't yet handle a file that
redefines a local variable.
This required a bunch of plumbing, but I think it came out okay.
We now generate FormatDescriptors with WeakSymbolRefs for direct
page references that match variable table entries.
LocalVariableTable got a rewrite. We need to be unique in both
name and address, but for the address we have to take the width into
account as well. We also want to sort the display by address
rather than name. (Some people might want it sorted by name, but
we can worry about that some other time.)
Updated the DefSymbol editor to require value uniqueness. Note
addresses and constants exist in separate namespaces.
The various symbols are added to the SymbolTable so that uniqueness
checks work correctly. This also allows the operand generation to
appear to work, but it doesn't yet handle redefinition of symbols.
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.
In the cross-reference table we now indicate whether the reference
source is doing a read, write, read-modify-write, branch, subroutine
call, is just referencing the address, or is part of the data.
The cc65 assembler runs in a single pass, which means forward
address references default to 16 bits. For zero-page references
we have to add an explicit width disambiguator. (This is an
unusual situation that only occurs if you have a zero-page .ORG
in the file after code that references it.)
With this change, 2014-label-dp passes, and no other regression
tests were affected.
(issue #40)
There are some useful interactions between C/N and maybe Z. Added
a quick test to 1003-flags-and-branches.
Also, updated the 2008-address-changes tests. Change b37d3dba
extended the nearby-target range of out-of-file symbols by one, so
one line that didn't get an operand label now does.
These *almost* match what cc65 has, and are accepted as primary or
aliases by 64tass.
This combines the LAX and LXA operations. LXA is the immediate
form of LAX, and behaves somewhat differently (and is unstable).
I was treating them as two separate operations with independent
mnemonics, but that doesn't seem to be the preferred way to
handle it.
The cc65 generator wasn't generating LAX before; now it does. This
required nudging the width disambiguator, as LAX is a second
example of an instruction with both DP,Y and ABS,Y operands.
(issue #20)
