An implementation in Elixir of a compiler of the Jack language which targets the Jack virtual machine. This is a simplified version of the Java Virtual Machine.
ASM symbols:
| Symbol | Description |
|---|---|
| SP | Stack Pointer |
| LCL | local |
| ARG | argument |
| THIS | first half of pointer |
| THAT | second half of pointer |
| R13-R15 | Guessing we can just use these puppies |
| Xxx.j | Each static variable j in file XXX.vm is translated into the symbol Xxx.j. |
| Control symbols |
| 0-15 | 16 virtual registers | 16-255 | static variables | 256-2047 | STack | 2048-16483 | Heap | 16384-24575 | Memory mapped I/O
3 is this 4 is that 5 - 12 are temp pointer i should translate to 3 + i temp i should translate to 5 + i
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 Any VM function can use these segments to manipulate selected areas on the heap. General-purpose segments. Can be made to correspond to different areas in the heap. Serve various programming needs.
pointer A two-entry segment that holds the base addresses of the this and that segments. Any VM function can set pointer 0 (or 1) to some address; this has the effect of 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.