altseq.gvm

# A program that calculates a (-2)^n * 3 + 4 for a given n (only n > 1)
# Memory Layout:
#   0: N        (Provided with initialMemory);
#   1: Result   (Output of program)
#   2: j        (Used for iteration)

# Check the memory has at least one space (for N), clear the accumulator
CHECKMEM 1
CLEAR

# Set the values for the Result and set j = to 1
ADDCONST 1
INSERT 1
INSERT 2

# Grab N and check if j is greater than N (one greater than)
AT 0
ADDCONST 1
SUBMEM 2

# If N is still greater than j keep doing the exp, otherwise we jump to the constants
JUMPNZERO 2
JUMPZERO 9

# Get current value, multiply by -2, put it back, increment j, jump back to check if we are done
CLEAR
AT 1 
MULCONST -2
SET 1
AT 2
ADDCONST 1
SET 2
JUMPREL -12

# Multiply by 3
AT 1
MULCONST 3

# Add 4
ADDCONST 4
SET 1

# End Program
HALT