Example implementation of LC3

[JulianGCalderon]

This PRs adds an example implementation of a LC3 virtual machine, based on Write your Own Virtual Machine, by Justin Meiners and Ryan Pendleton.

I added the full implementation to examples/lc3. Additionally, I changed some elements of the standard library.

The implementation contains some FIX notes, that indicate that I had to use a hacky solution to workaround a current limitation of the language.

Some important features that are missing are:

• Call a method from inside of a method
• Take references of struct indexes or array elements: &self.field.inner or &self.field[3].
  • This allows for calling method on struct field elements.
• If-Else chains.
• Match statement for non enum values.
• C-like Enums?
• Initializing static arrays without specifying every value: [0; 3] instead of [0, 0, 0].
• Bitwise operations: &, <<, >>.

Debugging is also bit difficult right now, as we don't have a good way to format values. The workaround I found is to write raw data to a file, and read it with another tool. As an example, I added a justfile with some commands that allowed me to inspect the raw data.

Implementation

• Inst: BR
• Inst: ADD
• Inst: LD
• Inst: ST
• Inst: JSR
• Inst: AND
• Inst: LDR
• Inst: STR
• Inst: RTI
• Inst: NOT
• Inst: LDI
• Inst: STI
• Inst: JMP
• Inst: RES
• Inst: LEA
• Inst: TRA
  • Trap: GETC
  • Trap: OUT
  • Trap: PUTS
  • Trap: IN
  • Trap: PUTSP
  • Trap: HALT

[github-actions]

Benchmarking (Linux) factorial

Compiling factorial (factorial.con)
Finished release in 34.454042ms
Running 5000000 iterations
Using input value: 20
Concrete Result = 2432902008176640000 Time taken : 97.03 ms
Rust Result = 2432902008176640000 Time taken : 60.42 ms

Benchmarking (Linux) fib

Compiling fib (fib.con)
Finished release in 27.514688ms
Running 5000 iterations
Using input value: 20
Concrete Result = 6765 Time taken : 136.85 ms
Rust Result = 6765 Time taken : 85.67 ms

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.29%. Comparing base (4802a28) to head (ff12de7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #231   +/-   ##
=======================================
  Coverage   56.29%   56.29%           
=======================================
  Files          25       25           
  Lines        5516     5516           
=======================================
  Hits         3105     3105           
  Misses       2411     2411           

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[github-actions]

Benchmarking (macOS) factorial

Compiling factorial (factorial.con)
Finished release in 632.687042ms
Running 5000000 iterations
Using input value: 20
Concrete Result = 2432902008176640000 Time taken : 29.77 ms
Rust Result = 2432902008176640000 Time taken : 23.50 ms

Benchmarking (macOS) fib

Compiling fib (fib.con)
Finished release in 107.599833ms
Running 5000 iterations
Using input value: 20
Concrete Result = 6765 Time taken : 92.85 ms
Rust Result = 6765 Time taken : 101.89 ms