SixtyPical

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 execute, analyze, and compile SixtyPical programs to 6502 machine code.

It is a work in progress, currently at the proof-of-concept stage.

The current released version of SixtyPical is 0.6. The current development version of SixtyPical, unreleased as of this writing, is 0.7-PRE.

Documentation

• Design Goals — coming soon.
• SixtyPical specification
• SixtyPical 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

For 0.7:

• always analyze before executing or compiling, unless told not to
• word type.
• word table type.

For 0.8:

• zero-page memory locations.
• indirect addressing.

At some point...

• trash instruction.
• interrupt routines.
• 6502-mnemonic aliases (sec, clc)
• other handy aliases (eq for z, etc.)
• have copy instruction able to copy a constant to a user-def mem loc, etc.
• add absolute addressing in shl/shr, absolute-indexed for add, sub, etc.
• check and disallow recursion.