stackalc

stackalc is a terminal-based stack calculator that lets you write mathematical expressions and see how they translate into a minimal, CIL-inspired instruction set. Whether you're experimenting with infix notation, exploring postfix (Reverse Polish Notation), or writing stack instructions directly, stackalc gives you a clear view of how expressions are broken down and executed step-by-step.

It features a clean, responsive terminal UI (TUI) built with ratatui, showing a list containing the generated instructions, the state of the stack at every stage of execution and a memory table that shows the values contained on the 32 registers. This makes it ideal for learning how stack-based execution works under the hood.

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How to Use

Press TAB to switch into input mode and type an expression or a sequence of instructions, depending on the selected mode. When you're ready, press ENTER to compile and execute your input. You can press Q at any time to quit.

stackalc will parse your input and generate a list of stack-based operations. These instructions are displayed in a scrollable view, and you can step through them one by one using the Down arrow key to see how the virtual stack evolves with each instruction.

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Input modes

There are three input modes available:

• INFIX mode is what most people are used to: expressions like 3 + 4 * 2 are supported, including parentheses and operator precedence.

• POSTFIX mode uses Reverse Polish Notation (RPN), where operators come after the operands. For example, 3 4 2 * + is equivalent to the infix version above.

• RAW mode lets you write stack instructions manually. It's intended for directly inputting the instructions yourself.

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Instruction Set

The core of stackalc is its simple yet expressive instruction set, modeled after CIL operations. It supports basic arithmetic, comparisons, and stack manipulation:

• ldc:<value> pushes a constant floating-point number onto the stack.
• ldv:<index> pushes the value of the specified register onto the stack.
• stv:<index> pops the top value from the stack and stores it into the specified register.
• neg negates the top value on the stack.
• add pops the top two values, adds them, and pushes the result.
• sub pops the top two values, subtracts the second-from-top from the top, and pushes the result.
• mul pops the top two values, multiplies them, and pushes the result.
• div pops the top two values, divides the second-from-top by the top, and pushes the result.
• ceq compares the top two values for equality and pushes 1 if they're equal, 0 otherwise.
• cgt checks if the second-from-top is greater than the top value and pushes 1 if true, 0 otherwise.
• clt checks if the second-from-top is less than the top value and pushes 1 if true, 0 otherwise.
• dup duplicates the top value on the stack.
• pop removes the top value from the stack.
• nop does nothing.
• rng pushes a random float between 0.0 and 1.0.
• br:<value> unconditionally jumps to the specified index.
• brtrue:<value> pops the top value; if it is non-zero, jumps to the specified index; otherwise, continues normal execution.
• brfalse:<value> pops the top value; if it is zero, jumps to the specified index; otherwise, continues normal execution.

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Build

git clone https://github.com/Ikken9/stackalc.git
cd stackalc
cargo build --release