VM to Hack Assembly Translator

This is part of nand2tetris, extending my other project (Flinner/HackAssembler: An Assembler written in V).

Objective

Build a VM translator, conforming to the VM Specification, and to the Standard VM-on-Hack Mapping, Project 07 | nand2tetris focusing on the implementation of the VM language's stack arithmetic and memory access commands.

Usage

hackvmtranslator [file]

where file is the .vm file to be translated. Output is to stdout

Specification

Diagram

Arithmetic and Logical Commands

Command	Return value (after popping the operand/s)	Comment
`add`	`x + y`	Integer addition (2’s complement)
`sub`	`x- y`	Integer subtraction (2’s complement)
`neg`	`- y`	Arithmetic negation (2’s complement)
`eq`	`true if x ¼ y, else false`	Equality
`gt`	`true if x > y, else false`	Greater
`lt`	`true if x < y, else false`	Less than
`and`	`x And y`	Bit-wise
`or`	`x Or y`	Bit-wise
`not`	`Not y`	Bit-wise

Memory Access Commands

Segment	Purpose	Comments
`argument`	Stores the function’s arguments.	Allocated dynamically by the VM implementation when the function is entered.
`local`	Stores the function’s local variables.	Allocated dynamically by the VM implementation and initialized to 0’s when the function is entered.
`static`	Stores static variables shared by all functions in the same .vm file.	Allocated by the VM imp. for each .vm file; shared by all functions in the .vm file.
`constant`	Pseudo-segment that holds all the constants in the range 0 . . . 32767.	Emulated by the VM implementation; Seen by all the functions in the program.
`this` `that`	General-purpose segments. Can be made to correspond to different areas in the heap. Serve various programming needs.	Any VM function can use these segments to manipulate selected areas on the heap.
`pointer`	A two-entry segment that holds the base addresses of the this and that segments.	Aligning the this (or that) segment to the heap area beginning in that address.
`temp`	Fixed eight-entry segment that holds temporary variables for general use.	May be used by any VM function for any purpose. Shared by all functions in the program.

Program Flow Commands

label	symbol      // Label declaration
goto	symbol      // Unconditional branching
if-goto symbol      // Conditional branching

Function Calling Commands

function functionName nLocals   // Function declaration, specifying the
                                // number of the function’s local variables
call functionName nArgs	        // Function invocation, specifying the
                                // number of the function’s arguments
return                          // Transfer control back to the calling function

Flinner / VM-Translator