d4rk-kn1gh7 / toy-vm

Toy VM in Rust

toy-vm

A toy register-based virtual machine written entirely from scratch in Rust.

Registers are numbered R0-R7, and each is 32 bits in size.

The vm also contains a stack (a 32 bit vector), and a few special registers:

• pc - program counter
• sp - stack pointer
• bp - base pointer
• eq - equality flag

List of opcodes

Opcode Name	Argument 1	Argument 2	Description
PUSH	Register	-	Pushes the value stored in a register onto the stack
POP	Register	-	Pops the value on the top of the stack into a register
LD8	Register	8-bit number	Load a 8 bit value into a register
LD16	Register	16-bit number	Load a 16 bit value into a register
MOV	Register	Register	Move value stored in second register to first register
ADD	Register	Register	Add values in 2 registers, result stored in first one
SUB	Register	Register	Subtract values in 2 registers, result stored in first one
MULT	Register	Register	Multiply values in 2 registers, result stored in first one
DIV	Register	Register	Divide values in 2 registers, result stored in first one
MOD	Register	Register	Modulus of values in 2 registers, result stored in first one
LS	Register	8-bit value	Left shift the value in a register by 8-bit value
RS	Register	8-bit value	Right shift the value in a register by 8-bit value
EQ	Register	Register	Set equality flag if values in 2 registers are equal
GT	Register	Register	Set equality flag if value in reg1 > reg2
LT	Register	Register	Set equality flag if value in reg1 < reg2
JMP	8-bit value	-	Set the PC to the given value
JE	8-bit value	-	Set the PC to the given value if equality flag is set
JNE	8-bit value	-	Set the PC to the given value if equality flag is not set
JF	8-bit value	-	Relative jump forwards by value (add pc)
JB	8-bit value	-	Relative jump backwards by value (subtract pc)
READ	Register	-	Reads a 32 bit integer into a register from stdin
WRITE	Register	-	Writes the value in a register to stdout

Running

You can run the project with cargo run <path-to-asm-file> A sample asm file is test.asm