SuperVM

SuperVM is a stack machine with a simple, but flexible command set.

The Stack

The virtual machine utilizes a stack to provide operands to instructions. This stack stores temporary values the program is working with.

Registers and Flags

The SuperVM virtual machine is a stack machine, but has also some control registers that can be set with special instructions. The registers mainly control stack access or control flow.

Mnemonic	Register	Function
SP	Stack Pointer	Stores the current 'top' position of the stack.
BP	Base Pointer	Stores the current stack frame position.
CP	Code Pointer	Stores the instruction which is executed next.
FG	Flag Register	Stores the state of the flags.

Stack Pointer

The stack pointer points to the top of the stack. Each push operation increases the stack pointer by one, each pop operation reduces it by one.

Base Pointer

The base pointer is a pointer that can be set to access the stack relative to it. The indended use is to create a stack frame with the base pointer by pushing the previous base pointer to the stack and setting the new base pointer to the current stack pointer.

Returning a function with this mechanism is moving the stack pointer to the current base pointer, then popping the previous base pointer from the stack.

Flag Register

Bit	Flag	Option
0	Zero	Is set when the output is zero.
1	Negative	Is set when the MSB is set.

Instructions

An SuperVM instruction is composed of multiple components:

Component	Range	Size	Function
execution Z	See below.	2	Excution dependend on Zero?
execution N	See below.	2	Excution dependend on Negative?
input0	Zero/Pop/Peek/Arg	2	Where does input0 come from?
input1	Zero/Pop	1	Where does input1 come from?
command	[6bit]	6	Which command is executed?
cmdinfo	[16bit]	16	Parameter value for the command.
flagmod	yes/no	1	Does this command modifies flags?
output	Discard/Push/Jump	2	What is done with the output?
argument	[32bit]	32	Some commands can take extra information

Execution Modes

The execution mode checks whether the instruction will be execution or not. The execution depends on the state of the flags. An X means "Don't care", a 0 means the flag must be cleared and a 1 means the flag must be set.

An instruction is only executed when all conditions are met.

Flag	Range
Zero	X/0/1
Negative	X/0/1

Commands

ID	Command	Action
0	COPY	output = input0
1	STORE	output = MEMORY[input0] = input1
2	LOAD	output = MEMORY[input0]
3	GET	output = STACK[BP + input0]
4	SET	output = STACK[BP + input0] = input1
5	BPGET	output = BP
6	BPSET	output = BP = input0
7	RSTSTACK	output = SP = BP
8	MATH	output = input0 OP[info] input1
9	SPGET	output = SP + input0
10	SPSET	output = SP + input0 = input1
11	SYSCALL	output = SysCall(input0, input1)
12	HWIO	output = HardwareIO(input0, input1)
13
14
15

Math

The math operator is a compound operator that contains all arithmetic operations. The arithmetic operation is selected by the cmdinfo.

cmdinfo	Operation
0	Addition
1	Subtraction
2	Multiplication
3	Division
4	Euclidean Division / Modulo
5	Bitwise Logic And
6	Bitwise Logic Or
7	Bitwise Logic Xor
8	Bitwise Logic Not
9	Rotating Bit Shift Left
10	Rotating Bit Shift Right
11	Arithmetic Bit Shift Left
12	Arithmetic Bit Shift Right
13	Logic Bit Shift Left
14	Logic Bit Shift Right

Assembler Mnemonics

Mnemonic	Arg?	i0	i1	Cmd	CmdInfo	Output	Flags?
nop	no	zero	zero	copy	0	discard	no
push	yes	arg	zero	copy	0	push	no
drop	no	pop	zero	copy	0	discard	no
dup	no	peek	zero	copy	0	push	no
jmp	yes	arg	zero	copy	0	jump	no
jmpi	no	pop	zero	copy	0	jump	no
ret	no	pop	zero	copy	0	jump	no
load	yes	arg	zero	load	0	push	no
loadi	no	pop	zero	load	0	push	no
store	yes	arg	pop	store	0	discard	no
storei	no	pop	pop	store	0	discard	no
get	yes	arg	zero	get	0	push	no
geti	no	pop	zero	get	0	push	no
set	yes	arg	pop	set	0	discard	no
seti	no	pop	pop	set	0	discard	no
bpget	no	zero	zero	bpget	0	push	no
bpset	no	pop	zero	bpset	0	discard	no
add	no	pop	pop	math	0	push	no
sub	no	pop	pop	math	1	push	no
cmp	no	pop	pop	math	1	discard	yes
mul	no	pop	pop	math	2	push	no
div	no	pop	pop	math	3	push	no
mod	no	pop	pop	math	4	push	no
and	no	pop	pop	math	5	push	no
or	no	pop	pop	math	6	push	no
xor	no	pop	pop	math	7	push	no
not	no	pop	zero	math	8	push	no
rol	no	pop	pop	math	9	push	no
ror	no	pop	pop	math	10	push	no
asl	no	pop	pop	math	11	push	no
asr	no	pop	pop	math	12	push	no
shl	no	pop	pop	math	13	push	no
shr	no	pop	pop	math	14	push	no
syscall	yes	zero	zero	syscall	0	discard	no
hwio	yes	zero	zero	hwio	0	discard	no

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