#!/usr/bin/awk -f

@include "vm.awk"

# Complex test program
BEGIN {
    # Test program to calculate factorial of 5
    i = 0
    
    # Push 5 onto stack
    image[i++] = pack_opcodes(OP_LIT, 0, 0, 0)
    image[i++] = 5
    
    # Push 1 onto stack (accumulator)
    image[i++] = pack_opcodes(OP_LIT, 0, 0, 0)
    image[i++] = 1
    
    # Start of multiplication loop
    loop_start = i
    
    # Duplicate top number (counter)
    image[i++] = pack_opcodes(OP_DUP, 0, 0, 0)
    
    # Test if counter is zero
    image[i++] = pack_opcodes(OP_ZERO_EXIT, 0, 0, 0)
    
    # Multiply accumulator by counter
    image[i++] = pack_opcodes(OP_MUL, 0, 0, 0)
    
    # Decrement counter
    image[i++] = pack_opcodes(OP_LIT, 0, 0, 0)
    image[i++] = 1
    image[i++] = pack_opcodes(OP_SUB, 0, 0, 0)
    
    # Jump back to start of loop
    image[i++] = pack_opcodes(OP_LIT, 0, 0, 0)
    image[i++] = loop_start
    image[i++] = pack_opcodes(OP_JUMP, 0, 0, 0)
    
    # Halt
    image[i++] = pack_opcodes(OP_HALT, 0, 0, 0)
    
    # Execute program
    execute(0)
    
    # Print result (should be 120 - factorial of 5)
    print "Factorial of 5:", stack_tos("data")
}

function pack_opcodes(op1, op2, op3, op4) {
    return op1 + (op2 * 256) + (op3 * 65536) + (op4 * 16777216)
}