smallvmA very minimal virtual machine written in rust.
The virtual machine has:
8 Registers
A stack
A heap
Data types include: u8, i8, u16, i16, u32, i32, u64, i64, f32, f64
Instruction Set
Root assembly instructions
Instruction
Left Input
Right Input
Operation
NOP
No Operation
MOV
Register
Variable
Move variable to register
MOVR
Register
Register
Move register contents to another register
JMP
Register
Jump to memory location
JE
Register
Jump if equal
JNE
Register
Jump not equal
JG
Register
Jump if greater
JL
Register
Jump if less
CMP
Register
Register
Compare two registers
ADD
Register
Register
Add 2 registers, push result to stack
SUB
Register
Register
Subtract 2 registers, push result to stack
MUL
Register
Register
Multiply 2 registers, push result to stack
DIV
Register
Register
Divide 2 registers, push result to stack
AND
Register
Register
Bitwise AND on 2 registers, push result to stack
OR
Register
Register
Bitwise OR on 2 registers, push result to stack
XOR
Register
Register
Bitwise Exclusive OR on 2 registers, push result to stack
SHR
Register
Variable
Shift register to the right by Variable
SHL
Register
Variable
Shift register to the left by Variable
VPUSH
Variable
Push variable contents on to stack
VPUSHR
Register
Push register contents on to stack
VPOP
Variable
Pops variable from stack to register
CALL
Register
Calls function at address in the register
RET
Return from routine
HALT
Halt CPU/Exit
VSTORE
Address
Variable
Store var into VMHeap at specific address from stack
VLOAD
Address
Load var from VMHeap and push value to stack
VSTORER
Address
Register
Store var in VMHeap from register contents
VLOADR
Register
Address
Loads a variable from VMHeap to register
Debugging assembly instructions
Instruction
Left Input
Right Input
Operation
PRINTR
Register
Print contents of register
PRINTV
Address
Print contents of variable at address
Example Program:1 0 0 10 MOV(R0, 10)
1 1 0 8 MOV(R1, 8)
1 2 0 22 MOV(R2, 23) Location to jump to if R0 is greater than R1
1 3 0 25 MOV(R3, 25) Location to jump to otherwise
6 0 1 CMP(R0, R1)
23 2 JG(R2) Jump if R0 is greater than R1
3 3 JMP(R3)
7 0 PRINTR(R0)
22 HALT()
7 1 PRINTR(R1)
22 HALT()
