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Implement a Scheme REPL based on the Ribbit VM #39

Merged
merged 221 commits into from
Mar 30, 2024
Merged

Implement a Scheme REPL based on the Ribbit VM #39

merged 221 commits into from
Mar 30, 2024

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mossprescott
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This involved a lot of side projects, including:

  • Implement an enhanced CPU with a larger, flat memory space with RAM and ROM both containing both instructions and data. In the process, the hardware simulators were made significantly more general with little apparent performance impact.
  • Implement a separate UI harness simulating a character-mapped display to save some RAM (2K for 80x25 characters vs. 16K for 512x256 pixels) and simplify text interaction.
  • Improve the compiler in [alt/reg.py] to generate much more compact code, and to provide access to assembly-level addresses and invocations.

@mossprescott
Make the Vector wrapper more flexible
f62467f 
Handle presence or absence of ROM, RAM(s), etc. separately, and fail lazily.
This allows alternate implementations pick and choose which components to use.
@mossprescott
“Big” computer, with large, flat memory
7cf9749
@mossprescott
Comments
1f3be94
@mossprescott
Actually parse hex literals in @-instructions
312c347
@mossprescott
First example for big.py
4775886
@mossprescott
More options for symbols and statics
3433e5c 
BUILTIN_SYMBOLS can be overridden.

If min_statics is None, any use of an undeclared symbol is a ParseError.

Range-checking for constant values.

A ParseError type for slightly more clarity about where the errors are coming from.
@mossprescott
Cleanup
d2fd7fe
@mossprescott
Use new SCREEN builtin
0ab953d
@mossprescott
Use an old trick to take 2 instructions out of each loop iteration
8a665af
@mossprescott
Use new assembler features
319123d
@mossprescott
Parse “#-“ data when assembling
831657d
@mossprescott
Comment, organize, and cleanup
98098b2
@mossprescott
More ROM size feedback
efdef91
@mossprescott
Handle keydown and TTY
15118a5
@mossprescott
Fix spurious writes when reading from keyboard
5310172
@mossprescott
In-progress: practice moving chars between keyboard and screen
d1df3db
@mossprescott
Correct some alignment errors
27e3f9c
@mossprescott
Fix alignment for delimiters and 1
2bc6ae4 
According to System 7.5.3 in emulation.
@mossprescott
Commit the screenshot for reference
3cd2e32
@mossprescott
Actually, assembler-allocated statics are a great idea after all
a8e8f5e
@mossprescott
Deal with shifted keys being held down
b504b0f
@mossprescott
Update very outdated comment
27f283b
@mossprescott
Update to clarify why big.py doesn’t get a proper comparison
90435ab
@mossprescott
Write raw characters from tty to stdout
00723ae
@mossprescott
Fix ROM size TODO to make more sense
a9fac8c
@mossprescott
Update for latest
944cc3f
@mossprescott
A different hack for accessing SP
8f62cd3
@mossprescott
Improve some random comments
2dc5a13
@mossprescott
First steps towards executing (Ribbit) scheme
2441a83 
Run rsc and decode the symbol table into ROM and (at runtime) RAM.

Not really dealing with instructions yet, but the path is becoming clear.
@mossprescott
Possibly legit decoding of instructions
0d739b7
@mossprescott
Manually disable the ##feature-arity-check flag
d1bae37
@mossprescott
Fix typo: was logging wrong field of unrecognized “pair”
51f012d
@mossprescott
Line editing
befeb97 
The first call to getchar captures an entire line of input, then pushes the characters one at a time.

This makes the REPL behave in a sensible way, and can handle backspace. It also means that most text entry is always happening when the interpreter is in a type loop handling getchar, so it’s much more responsive.
@mossprescott
Update decsription of getchar and memory layout
ef47d36
@mossprescott
Echo a line at a time, to show the new behavior
dc19911
@mossprescott
Implement quotient; fixing int->string
c466b59
@mossprescott
Elide unreachable jump after return
67208c2
@mossprescott
Remove some spurious comments
8489219
@mossprescott
Neevermind with locals; factor out recursive divide with fewer redund…
af45ee2 
…ant checks
@mossprescott
Show mem consumption when not tracing
c61583b
@mossprescott
Add screen capture of the REPL
29d7bbc
@mossprescott
Add a test for “eval” from the library
9cd4b62
@mossprescott
Run quotient tests only on the Jack interpreter
96db8c2 
And fix an error
@mossprescott
Don’t double-quote strings
3aad0f6
@mossprescott
Don’t quote unrecognized ribs; fix tests
8f2d85f
@mossprescott
Remove dead code
5e846fc
@mossprescott
Add a link to scheme
a9080d6
@mossprescott
Keep original rom size when overwriting the contents
5a1358b
@mossprescott
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A few bugs have been sorted out, and the getchar/putchar opcodes are now more responsive and support simple line editing.

That's sufficient to make this "usable".

In the REPL, a couple of simple expressions will consume the available memory, so we'll need a garbage collector to make this any more real.

@mossprescott
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Calling this good enough to merge. Planning to add pointer tagging and garbage collection on another branch.

@mossprescott mossprescott merged commit e8b7147 into master Mar 30, 2024
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@mossprescott mossprescott deleted the scheme branch March 30, 2024 21:41
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@mossprescott