A VM for a fantasy CPU in lua/love

Features:

• Stacks
• Registers
• External device communication (so you can interface with code outside the VM very easily)
• Extremely simple instruction definition

Fibonacci

Communication with external 'device'

The instruction set is defined in is.lua While the cpu's 'functionality' is defined in cpu.lua

"Types" for the instruction arguments are as follows:

Alias

A registers address, for example R10

Number

A numeric type, for example 0.1

String

A weird choice for a VM, it exists nonetheless, strings are surrounded by "", like "Hello World"

Any

A compound type, acts like a union between all the first 3, mostly meant for math operations so you can

ADDR:10,10,R10

rather than storing the numbers in seperate registries

Syntax

The instruction syntax is very simple

multi argument instructions
INSTRUCTION:ARGUMENT1,ARGUMENT2
e.g
SET:R1,"Hello world"

single argument instructions:
INSTRUCTION:ARGUMENT1
e.g
SLP:0.5

no argument instruction (none currently present)
INSTRUCTION

and a special case for the 'instruction' of the label
{LABEL_NAME}
and later can be referenced in jmp instructions like
JMP:LABEL_NAME

Current instruction set is

SET:ALIAS,ANY X | Sets the value of ALIAS to ANY X

ADDR:ANY X,ANY Y,ALIAS | Adds the values of x and y, sets result in to ALIAS

DIV:ANY X,ANY Y,ALIAS | Divides x by y, stores the result in ALIAS

MOD:ANY X,ANY Y,ALIAS | Modulo of x/y, result stored in ALIAS

ADD:ALIAS, ANY X | Adds x to value already in alias

MOV:ALIAS X, ALIAS Y | Moves the value of registry x to registry y

JMP:LABEL | Unconditional Jump to {LABEL}

JMPL:ANY X, ANY Y, LABEL | jumps to {LABEL} if x > y

JMPI:ANY X, LABEL | Jumps to {LABEL} if x > 0

CMPL:ANY X, ANY Y, ANY Z, ALIAS A | Sets the value of a to z if x>y

CMPE:ANY X, ANY Y, ANY Z, ALIAS A | Sets the value of a to z if x==y

CMPN:ANY X, ANY Y, ANY Z, ALIAS A | Sets the value of a to z if x!=y

SLP:ANY X | Sets the CPU to sleep for value of x

PUSH:ANY A, ANY B, ANY C, ANY D, ANY E, ANY F | Pushes [a, b, c, d, e, f] on to the stack (values after A are optional)

POP:ALIAS A, ALIAS B, ALIAS C, ALIAS D, ALIAS E, ALIAS F | Retrieves the [a, b, c, d, e, f] from the stack (aliases after A are optional)

CCAT:ALIAS A | Concatenates the current stack and places the result in to A

SUM:ALIAS A | Sums the value of the stack and places the result in to A

Available registers:

Hardcoded:

These first 2 are possibly deprecated in

RMA - Register memory address

Sets the memory address for access

RMD - Register memory data

This will contain the current data for the current memory address set by (RMA)

RDBA - Register Device bus address

Points the device bus at desired device

RDMA - Register Device memory address

Points to the desired memory address for the active RDBA device

RDMD - Register Device memory data

Contains data from the RDBA device on the RDMA address, can be set or get like a regular register for manipulation

R1 - R10 Are the default general purpose registers, but more can be set in cpu.lua with gpRegisterAmount variable