glVM (short for Glimmer VM) is a stack-based virtual machine with a concise instruction set, bytecode file parsing, and an exposed API for building programs at compile time. The bytecode that this machine runs has support for function calls, control flow, and int/float/string computations. The machine itself is also tested at 100% code coverage.
| Instruction | Arity | Description |
|---|---|---|
| NOOP | 0 | Do nothing |
| PUSH | 1 | Push a given value onto the stack |
| CALL | 1 | Push a new frame on the call stack and jump to the given label |
| RET | 0 | Pop a frame off of the call stack and jump to its return address |
| SET | 1 | Pops the stack and binds that value to a given name in the current frame |
| GET | 1 | Push the value of a given name in the current frame onto the stack |
| ADD | 0 | Pop 2 values off of the stack and push their sum |
| SUB | 0 | Pop 2 values off of the stack and push their difference |
| MUL | 0 | Pop 2 values off of the stack and push their product |
| DIV | 0 | Pop 2 values off of the stack and push their quotient |
| JE | 1 | Pop 2 values off of the stack and jump to the given label if the values are equal |
| JNE | 1 | Pop 2 values off of the stack and jump to the given label if the values are not equal |
| J | 1 | Unconditionally jump to the given label |
The following code snippet is a program that calculates the 20th fibbonacci number using recursive calls. You can try this yourself by having an installation of Go 1.18, cloning this repo, and running ./glVM _examples/fib.gbc. Try changing the number, but note that the spacing must be exactly like the given example as the parser is very simple.
@0: I(20)
@1: S("fib")
@2: S("n")
@3: I(0)
@4: S("NotZero")
@5: I(1)
@6: S("NotOne")
@7: I(2)
#main: PUSH @0
CALL @1
RET
#fib: SET @2
PUSH @3
GET @2
JNE @4
PUSH @3
RET
#NotZero: PUSH @5
GET @2
JNE @6
PUSH @5
RET
#NotOne: GET @2
PUSH @5
SUB
CALL @1
GET @2
PUSH @7
SUB
CALL @1
ADD
RET
Functioning machine that executes instructions, has stored data & labels
Push instruction to add item to stack
Integers + integer arithmetic
Floats + float arithmetic
Type promotion for int+float arithmetic
Strings + string concatenation
Conditionals + loops (jump structure of some sort, JE)
functions (call, jump, ret, call stack, fib test)
/program tests
/values tests
/frame tests
Disassembly for program
Bytecode file reading/execution (main executable)
Pimp out readme (instruction table, fib program, etc)
Booleans + boolean logic
Arrays + array operations
Standard Library (IO, helpers, etc)
Some sort of structs or classes
Make a compiler from a language to this bytecode
etc