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SixtyPical
Version 0.13. Work-in-progress, everything is subject to change.
SixtyPical is a very low-level programming language, similar to 6502 assembly, with static analysis through abstract interpretation.
In practice, this means it catches things like
- you forgot to clear carry before adding something to the accumulator
- a subroutine that you call trashes a register you thought was preserved
- you tried to write the address of something that was not a routine, to a jump vector
and suchlike. It also provides some convenient operations and abstractions based on common machine-language programming idioms, such as
- copying values from one register to another (via a third register when there are no underlying instructions that directly support it)
- explicit tail calls
- indirect subroutine calls
The reference implementation can analyze and compile SixtyPical programs to 6502 machine code.
Documentation
- Design Goals
- SixtyPical specification
- SixtyPical revision history
- Literate test suite for SixtyPical syntax
- Literate test suite for SixtyPical execution
- Literate test suite for SixtyPical analysis
- Literate test suite for SixtyPical compilation
- 6502 Opcodes used/not used in SixtyPical
TODO
Save registers on stack
This preserves them, so that, semantically, they can be used later even though they are trashed inside the block.
Re-order routines and optimize tail-calls to fallthroughs
Not because it saves 3 bytes, but because it's a neat trick. Doing it optimally is probably NP-complete. But doing it adeuqately is probably not that hard.
And at some point...
- Confirm that
and
can be used to restrict the range of table reads/writes. low
andhigh
address operators - to turnword
type intobyte
.const
s that can be used in defining the size of tables, etc.- Tests, and implementation, ensuring a routine can be assigned to a vector of "wider" type
- Related: can we simply view a (small) part of a buffer as a byte table? If not, why not?
- Check that the buffer being read or written to through pointer, appears in approporiate inputs or outputs set. (Associate each pointer with the buffer it points into.)
static
pointers -- currently not possible because pointers must be zero-page, thus@
, thus uninitialized.- Question the value of the "consistent initialization" principle for
if
statement analysis. interrupt
routines -- to indicate that "the supervisor" has stored values on the stack, so we can trash them.- Error messages that include the line number of the source code.
- Add absolute addressing in shl/shr, absolute-indexed for add, sub, etc.
- Automatic tail-call optimization (could be tricky, w/constraints?)
- Possibly
ld x, [ptr] + y
, possiblyst x, [ptr] + y
. - Maybe even
copy [ptra] + y, [ptrb] + y
, which can be compiled to indirect LDA then indirect STA!
Commit History
@e2d10d7d33dfb1e42808978a06089572efb99677
git clone https://git.catseye.tc/SixtyPical/
- Documentation/notes changes for the 0.13 branch. Chris Pressey 6 years ago
- Implement Context.copy_range(), ranges for constants. Progress! Chris Pressey 6 years ago
- Some headway on context.assert_in_range(). Chris Pressey 6 years ago
- Get and set top of range of a location. Make AND do this to A reg. Chris Pressey 6 years ago
- Check for table size (in parser, thus tests are for syntax.) Chris Pressey 6 years ago
- Add some initial failing tests. Chris Pressey 6 years ago
- Associate a range with each meaningful storage location in context. Chris Pressey 6 years ago
- Merge pull request #8 from catseye/develop-0.12 Chris Pressey (commit: GitHub) 6 years ago
- Don't fudge the name of IndexRefs; dig in to find the ref's name. Chris Pressey 6 years ago
- Small documentation sorting. Chris Pressey 6 years ago