Operation codes for virtual machine

Arithmetic operations

1. OP_ADD - addition. opStack[top-1] = opStack[top-1] + opStack[top], pop opStack[top]
2. OP_SUB - subtraction
3. MUL - multiplication
4. DIV - division

Stack operations

1. OP_PUSH_I8 val - put val (number) to callStack
2. OP_POP - remove top element from callStack
3. OP_DUP - duplicate a top element

Conditions & loops operations

1. OP_JMP addr - unconditional jump
2. OP_JZ addr - jump to addr if opStack[top] == 0
3. OP_JNZ addr - jump to addr if opStack[top] != 0
4. OP_JEQ addr - jump to addr if opStack[top-1] == opStack[top]; pop; pop
5. OP_JNE addr - jump to addr if opStack[top-1] != opStack[top]; pop; pop
6. OP_JLT addr - jump to addr if opStack[top-1] < opStack[top]; pop; pop
7. OP_JGT addr - jump to addr if opStack[top-1] > opStack[top]; pop; pop
8. OP_JLE addr - jump to addr if opStack[top-1] <= opStack[top]; pop; pop
9. OP_JGE addr - jump to addr if opStack[top-1] >= opStack[top]; pop; pop
10. OP_CMP_EQ - opStack[top-1] == opStack[top]; pop; pop; push
11. OP_CMP_NEQ - opStack[top-1] != opStack[top]; pop; pop; push
12. OP_CMP_LT - opStack[top-1] < opStack[top]; pop; pop; push
13. OP_CMP_GT - opStack[top-1] > opStack[top]; pop; pop; push
14. OP_CMP_LTE - opStack[top-1] <= opStack[top]; pop; pop; push
15. OP_CMP_GTE - opStack[top-1] >= opStack[top]; pop; pop; push
16. OP_CALL addr args_count localsCount - functions call, puts the return address to callStack; copies arguments from operation stack to locals of stack frame
17. OP_RET - destroys current call stack frame and returns to the previous one

Operations on variables

1. LOAD var_idx - move call stack frame locals[var_idx] to opStack[top]
2. STORE var_idx - move opStack[top] to call stack frame locals[var_idx]

Classes and objects

1. NEW class_id - create instance of class_id
2. GET_FIELD obj, field_id - get locals of object's variable
3. SET_FIELD obj, field_id, val - set locals to object's variable

I/O

1. OP_PRINT - top callStack element to stdout
2. READ - read input from stdin

VM internal

1. OP_HALT - stop virtual machine