instructions

Quick examples

Const 5 RegA
Compute Add RegA RegB RegC
Write RegA (Addr 0xFF)
Branch RegA (Rel 1)

Local instructions

Local instructions act on the local memory and registers only.

Instruction	a1	a2	a3	a4	Description
Const	Int	Reg			Store value a1 at a2
Compute	Operator	Reg	Reg	Reg	Store result of operator on a2, a3 in a4
Load	MemAddr	Reg			Load from address a1, store at a2
Store	Reg	MemAddr			Store a1 at a2
Branch	Reg	Target			Jump to a2 if value at a1 is not zero
Jump	Target				Jump to a1
Push	Reg				Push a1 to top of the stack
Pop	Reg				Pop from stack and store result at a1
Nop					Do absolutely nothing.
EndProg					Terminate program

System instructions

System instructions communicate with the external system (or shared memory). Read sends a request, but does not wait for the system to reply. Note that you can use this to issue multiple requests, and wait for their replies later on. Do keep in mind that inputs are non-buffered. That is, if you miss a reply by not waiting for an answer with Receive the message is lost forever.

Instruction	a1	a2	Description
Read	MemAddr		Send request to shared memory to fetch a1
Receive	Reg		Block and wait for a message to arrive (from system / shared memory). Store the result in a1
Write	Reg	MemAddr	Write a1 to shared memory a2
TestAndSet	MemAddr		If the rightmost bit of a1 is a one, do nothing and return zero. If it was a zero, write the integer one to the memory address and return one.

Types

The types mentioned in the table below can be used in the instructions above. For example, 'MemAddr' can either expand to 'Addr Int' or 'Deref Reg' (which can further expand to Addr 3 or Deref RegB).

Type	Resolves to	Description
Reg	Register	Architecture#Registers
MemAddr	Addr Int	Local or shared memory address Int
	Deref Reg	Local or shared memory address stored at Reg
Target	Abs Int	Instruction Int
	Rel Int	Current program counter plus Int
	Ind Reg	Instruction number stored at Reg
Operator	Add	Add
	Sub	Subtract
	Mul	Multiply
	Div	Divide
	Mod	Modulo
	Equal	Equals
	NEq	Not equals
	Gt	Greater than
	GtE	Greater than or equal to
	Lt	Lesser than
	LtE	Lesser than or equal to
	And	Bitwise AND
	Or	Bitwise OR
	Xor	Bitwise XOR
	LShift	Left shift
	RShift	Right shift