Byte Code

The Addie VM

Addie is an interpreted language for maximum portability. To be fast and efficient, we have chosen a register based virtual machine architecture.

Our fixed size bytecode instruction

Bytecode instructions are fixed in size (32 bits).

The operation layout

The OP code uses 8 bits. The structure of the remaining 24 bits depend on the OP code at hand.

31-24	23-16	15-8	7-0
A	B	C	OP
A2		C	OP
A3			OP

The core instruction set

As Addie is interpreted, we will try to use as many high level OPs as possible. To make comprehension simpler, we divide the OP codes into the core set and the extended set. The OP prefix and OP suffix are for mnemonics only, the two are baked together into a single byte.

OP prefix	OP suffix	Description
call	noarg fixarg vararg	Call a subroutine. The first operand is the return register. The second is the function to call. The following registers are the arguments.
deref		Translate a unresolved symbol to a value
ret		Return from a subroutine
jmp-if-true	r0 rx	Conditional jump

The extended instruction set

OP prefix	OP suffix	Description
s-call	noarg fixarg vararg	Call a subroutine. Merges a deref and a call operation. Works like call, but with the second operand being an unresolved symbol.