Virtual Machine (VM) Specification
The TechScript VM is a stack-based virtual machine written in Rust that executes optimized bytecode files (.txc).
🏗️ Core Architecture Components
1. Execution Stack
Stores runtime values. Binary math operators pop the top two values, execute calculations, and push results back.
2. Stack Frames
Each active function call pushes a new StackFrame holding:
- Instruction Pointer (IP): Points to the next bytecode offset.
- Locals Registers: Array storing local variables and parameters.
- Return Address: Frame to jump back to after the function returns.
🧬 NaN-Boxed Value Representation
To maximize cache locality, TechScript values are represented using 64-bit floating-point numbers:
- Float: Encoded directly.
- Int: Packed in special non-standard NaN payload space.
- Heap Pointer: Pointer addresses for strings, lists, maps, and classes are boxed into the unused bits of NaN double-precision floats.
🔁 Garbage Collector (GC)
- Automatic Reference Counting (ARC): Heap objects have an associated reference count. The VM immediately deallocates an object when its count falls to zero.
- Cycle Detector: Runs a periodic mark-and-sweep phase to resolve cyclic references (e.g. mutual self-references between objects).