Commit cfd99c69e228747ed72a68e273ae77413513cfa6 - SixtyPical

Tweaks to README. Cat's Eye Technologies 7 years ago

1 changed file(s) with 15 addition(s) and 10 deletion(s). Raw diff Collapse all Expand all

+15

-10

README.markdown less more

6	6	It is a work in progress, currently at the proof-of-concept stage.
7	7
8	8	It is expected that a common use case for SixtyPical would be retroprogramming
9		for the Commodore 64 and other 6502-based computers such as the VIC-20.
	9	for the Commodore 64 and other 6502-based computers such as the VIC-20, the
	10	Apple ][+, and the NES.
10	11
11	12	Many SixtyPical instructions map precisely to 6502 opcodes. However, SixtyPical
12	13	is not an assembly language: the programmer does not have total control over

28	29	If you have `ghc`, Ophis, and VICE 2.4 installed, clone this repo, `cd` into it,
29	30	and run
30	31
31		./loadngo.sh eg/demo.60p
	32	./loadngo.sh eg/game.60p
32	33
33	34	The Big Idea(s)
34	35	---------------

44	45	reserve byte lives
45	46	reserve word score
46	47	routine do_it {
47		lda score ; no! can't treat word as if it were a byte
48		lda lives, x ; no! can't treat a byte as if it were a table
	48	lda score // no! can't treat word as if it were a byte
	49	lda lives, x // no! can't treat a byte as if it were a table
49	50	}
50	51
51	52	### Abstract Interpretation ###

59	60	routine do_it {
60	61	lda #0
61	62	jsr update_score
62		sta vic_border_colour ; uh... what do we know about reg A here?
	63	sta vic_border_colour // uh... what do we know about reg A here?
63	64	}
64	65
65	66	...is illegal unless one of the following is true:
66	67
67	68	* the A register is declared to be a meaningful output of `update_score`
68		* `update_score` was determined to not change the value of the A register
	69	* `update_score` was analyzed and determined to not change the value of the
	70	A register
69	71
70	72	The first case must be done with an explicit declaration on `update_score`.
71	73	The second case will be be inferred using abstract interpretation of the code

151	153	--------------------
152	154
153	155	For more information, see the docs (which are written in the form of
154		Falderal literate test suites. If you have Falderal installed, you can run
155		the tests with `./test.sh`.)
	156	[Falderal](http://catseye.tc/node/Falderal) literate test suites. If you
	157	have `falderal` on your executable search path, you can run the tests with
	158	`./test.sh`.)
156	159
157	160	* [Checking](https://github.com/catseye/SixtyPical/blob/master/doc/Checking.markdown)
158	161	* [Analyzing](https://github.com/catseye/SixtyPical/blob/master/doc/Analyzing.markdown)

163	166	---------
164	167
165	168	Some (OK, a lot) of the Haskell code is kind of gross and non-idiomatic.
166		The parser, in particular, would not be described as "elegant". There
	169	The parser, in particular, could not be described as "elegant". There
167	170	could definitely be more higher-order functions defined and used. At the
168	171	same time, I'm really not a fan of pointless style — I prefer it when things
169	172	are written out explicitly and pedantically. Still, there are places where

173	176	are translated into an intermediate representation which is arguably CISC-like.
174	177	For example, `lda`, `sta`, `ldx`, and `tax` all become kinds of `COPY`
175	178	internally. This internal instruction set is much smaller than the 6502's,
176		and thus is usually easier to analyze.
	179	and thus is usually easier to analyze. It would also be easier to adapt to
	180	other instruction sets, such as the Z80 or the 8086.
177	181
178	182	Notes
179	183	-----

213	217	* Addressing modes — indexed mode on more instructions
214	218	* Rename and lift temporaries in nested blocks
215	219	* Tail-recursion optimization
	220	* `word 100` to promote an otherwise 8-bit literal to a 16-bit value
216	221	* `jmp routine`
217	222	* Enforce that `jmp`s come at ends of blocks(?)
218	223	* `outputs` on externals