EIP-2565 Pricing Python.py

#!/usr/bin/python3

import json
import math


# New EIP
def calculate_multiplication_complexity(base_length, modulus_length):
    max_length = max(base_length, modulus_length)
    words = math.ceil(max_length / 8)
    return words**2

def calculate_iteration_count(exponent_length, exponent): # same as ADUSTED_EXPONENT_LENGTH in EIP-198
    iteration_count = 0
    if exponent_length <= 32 and exponent == 0: iteration_count = 0
    elif exponent_length <= 32: iteration_count = exponent.bit_length() - 1
    elif exponent_length > 32: iteration_count = (8 * (exponent_length - 32)) + ((exponent & (2**256 - 1)).bit_length() - 1)
    return max(iteration_count, 1)

def calculate_gas_cost(base_length, modulus_length, exponent_length, exponent):
    multiplication_complexity = calculate_multiplication_complexity(base_length, modulus_length)
    iteration_count = calculate_iteration_count(exponent_length, exponent)
    return max(200, math.floor(multiplication_complexity * iteration_count / 3))

# Orig EIP 198
def calculate_old_multiplication_complexity(x):
    if x <= 64: return x ** 2
    elif x <= 1024: return ((x ** 2) // 4) + ((96 * x) - 3072)
    else: return ((x ** 2) // 16) + ((480 * x) - 199680)

def calculate_old_gas_cost(base_length, modulus_length, exponent_length, exponent):
  GQUADDIVISOR = 20
  mul_complex = calculate_old_multiplication_complexity(max(base_length, modulus_length))
  adj_exp_len = calculate_iteration_count(exponent_length, exponent)
  return math.floor(mul_complex * max(adj_exp_len, 1) / GQUADDIVISOR)

# Download EIP-198 test vectors - wget https://raw.githubusercontent.com/ethereum/go-ethereum/master/core/vm/testdata/precompiles/modexp.json
f = open('modexp.json')
vectors = json.load(f)

print("{:22}  {:8} {:8} {:8}".format('Name', 'Old Gas', 'Exp old', 'New Gas'))
for v in vectors:
  baselen = int(v['Input'][0:64], 16)
  explen  = int(v['Input'][64:128], 16)
  modlen  = int(v['Input'][128:192], 16)
  exp  = int(v['Input'][(192 + (baselen * 2)):(192 + ((baselen + explen) * 2))], 16)
  old_gas = calculate_old_gas_cost(baselen, modlen, explen, exp)
  exp_old_gas = v['Gas']
  new_gas = calculate_gas_cost(baselen, modlen, explen, exp)
  print("{:22} {:8} {:8} {:8}".format(v['Name'], old_gas, exp_old_gas, new_gas))