Bytecode Runner

中文

A simple bytecode runner

This is a bytecode execution emulator that supports bytecode similar to the Intel x86 format.

Quick Start

The program does not have any dependencies, so you can compile and run it directly after git clone https://github.com/SongZihui-sudo/bytecodeRunner.git.

Compile using xmake:

cd bytecodeRunner
xmake

Set the currently running bytecode program

There is a current_code_stream macro in the main.cpp file. You can configure this macro to control the program to be executed. one example:

static std::vector< std::string > asm_code_test7
= { "test_func():", "push ebp", "mov ebp, esp", "add 1, 1", "pr acc", "ret",
     "main():", "push ebp", "mov ebp, esp", "call test_func()", "leave", "ret" };

#define current_code_stream asm_code_test7

or
run code from text file.

visual_machine.visual_instruction_runner.load_file( "./example.asm" );

Instructions and syntax of bytecode

GRAMMAR

Command format:

Opcode address_code1, [address_code2]

Label:

xxx:
     instruction

Character: 'c'
Immediate number: 1,2,3,4,.....
Memory addressing: [immediate data/register/variable]

main() is the entry point of the entire program

INSTRUCTIONS

About the stack

push source(immediate/register/memory) Push source onto the stack.
pop [destination(register)] pop the top element of the stack into destination

Basic operations

add num1(immediate value/register/memory), num2(immediate value/register/memory) num1 + num2
sub num1(immediate value/register/memory), num2(immediate value/register/memory) num2 - num1
mul num1(immediate value/register/memory), num2(immediate value/register/memory) num1 * num2
div num1(immediate value/register/memory), num2(immediate value/register/memory) num2 / num1
cmp destination(immediate value/register/memory), source(immediate value/register/memory) Compare num1 and num2. If num1 > num2 -> SF=1, num1 < num2->SF= 0, num1 == num2->ZF=1, num1 != num2->ZF=0.

Jump

jmp destination(immediate value/register/memory/label) jumps directly to destination
jne destination(immediate value/register/memory/label) jumps if the result of cmp comparison is not equal
je destination(immediate value/register/memory/label) jumps if the result of cmp comparison is equal
jbe destination(immediate value/register/memory/label) jump if lower than or equal to (<=)
ja destination(immediate value/register/memory/label) jump if it exceeds (>)
jb destination(immediate/register/memory/label) jumps if the carry bit is set
jnb destination(immediate value/register/memory/label) jumps if the carry bit is not set
call destination(immediate/register/memory/label) calls the function at destination
ret returns from the called function
leave is used at the end of the main function to exit

debug

pr register_name(string) prints the contents of the register specified by register_name
pm source(number) count(number) prints count contents starting from the memory address source ps print stack
p message(string) print custom message exit exit

data transmission

mov source(immediate number/register/memory), destination(immediate number/register/memory)
let source(string) destination(immediate value) variable declaration

Example

test_func():
    push ebp
    mov ebp, esp
    add esp, 16
    mov esp, acc
    add ebp, 1
    mov [acc], 32
    add [acc], edi
    pr acc
    sub esp, 16
    mov esp, acc
    pop ebp
    ret
main():
    push ebp
    mov ebp, esp
    add esp, 16
    mov esp, acc
    mov edi, 1
    cmp edi, 0
    jne  22
    call test_func()
    sub esp, 16
    mov esp, acc
    pop ebp
    leave
    ret

output: acc: 21

TO-DO

• Implement functions through stack
• Implement function parameter passing and local variables
• Implement process control instructions
• register indirect addressing
• Maintenance of system stack through esp and ebp
• Floating point support
• string support
• Expression support