6502/SixtyPical
1
0
Fork 0
mirror of https://github.com/catseye/SixtyPical.git synced 2024-07-05 15:29:07 +00:00
Code Issues Projects Releases Wiki Activity
A 6502-oriented low-level programming language supporting advanced static analysis
230 Commits 1 Branch 23 Tags 1.3 MiB
Python 98.2%
Shell 1.5%
xBase 0.3%
b47cfc7b91
Go to file
Chris Pressey b47cfc7b91 Add some notes to the TODO section of the README.
2017-11-21 12:10:31 +00:00
bin Implement indirect JSRs with trampolines in theory; doesn't work. 2015-10-22 15:45:16 +01:00
doc Add draft of Design Goals document. 2017-11-21 11:13:21 +00:00
eg Support copy'ing a word constant to a word location. Joystick eg. 2017-11-20 15:18:21 +00:00
src/sixtypical Assert that the loop variable is meaningful in repeat. Unit test. 2017-11-20 16:39:39 +00:00
tests Assert that the loop variable is meaningful in repeat. Unit test. 2017-11-20 16:39:39 +00:00
.gitignore Refactor to replace some sketchy code with code actually in use. 2015-10-16 10:40:38 +01:00
.hgignore Refactor to replace some sketchy code with code actually in use. 2015-10-16 10:40:38 +01:00
.hgtags Added tag 0.6 for changeset f89772f47de9 2015-10-23 16:37:22 +01:00
HISTORY.markdown Add draft of Design Goals document. 2017-11-21 11:13:21 +00:00
LICENSE Add TODO to README, update license information. 2015-10-16 10:00:51 +01:00
loadngo.sh Call defined routines. 2015-10-17 15:23:00 +01:00
README.markdown Add some notes to the TODO section of the README. 2017-11-21 12:10:31 +00:00
test.sh Add syntax for extern routines, add syntax tests. 2015-10-17 13:50:21 +01:00

README.markdown

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 development version of SixtyPical is 0.8-PRE.

Documentation

TODO

byte buffer and pointer types. Basically, a buffer is a table that can be longer than 256 bytes, and a pointer is an address within a buffer. A pointer is implemented as a zero-page memory location, and accessing the buffer pointed to is implemented with indirect addressing. We will likely need a new instruction for this, or at least a mode, and it will likely trash the x register, and it will likely be unchecked, at least to start. Basically, this is to allow us to write to the byte buffer[2048] known as "the screen".

word table and vector table types.

low and high address operators (turn word type into byte.) Possibly.

Save registers on stack or in memory (this preserves them = not trashed).

And at some point...

  • initialized byte table memory locations
  • always analyze before executing or compiling, unless told not to
  • 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.
  • automatic tail-call optimization (could be tricky, w/constraints?)
  • re-order routines and optimize tail-calls to fallthroughs