generate.py

import random

# Make this higher when you want better graphs
iters = 100

def trunc(x):
    return x % (2**64)

def test_row(f, swaps):
    seen = set()
    diff_counts = [0] * 64

    for _ in range(iters):
        while True:
            x  = random.randrange(2**64)
            x &= random.randrange(2**64)
            x &= random.randrange(2**64)
            x &= random.randrange(2**64)
            x &= ~((1 << 32) - 1)

            # If we don't do this, there's
            # huge bias towards certain values,
            # even for completely random functions
            if x not in seen:
                seen.add(x)
                seen.add(x ^ swaps)
                break

        diffs = f(x) ^ f(x ^ swaps)

        for i in range(64):
            if (diffs >> i) & 1:
                diff_counts[i] += 1

    return diff_counts


BAD = 2
chars = " "*BAD + "░▒▓" + "█"*BAD
def format_row(row, ord):
    return "".join(chars[x * len(chars) // (iters+1)] for x in ord(row))

def display():
    ord = reversed
    for i in reversed(range(64)):
        print(
            format_row(test_row(f1, 1 << i), ord),
            format_row(test_row(f2, 1 << i), ord),
            format_row(test_row(f3, 1 << i), ord),
        )
    print()



# For SVG output:

# def format_row(row, x, y, ord):
#     for i, count in enumerate(ord(row)):
#         yield "<rect x='{}' y='{}' width='4.1' height='4.1' fill='rgb({},{},{})'/>".format(
#             x * 4 + i * 4, (63-y) * 4, count * 255 / (iters+1), 0, 0
#         )

# def display():
#     ord = reversed
#     print("<svg width='256' height='256' version='1.1' xmlns='http://www.w3.org/2000/svg'>")
#     for i in reversed(range(64)):
#         print(*format_row(test_row(f1, 1 << i),   0, i, ord))
#         print(*format_row(test_row(f2, 1 << i),  70, i, ord))
#         print(*format_row(test_row(f3, 1 << i), 140, i, ord))
#     print()




def f1(x):
    x = trunc(x * 0x6eed4e9da4d94a4b)
    x ^= (x >> 32) >> (x >> 60)
    x = trunc(x * 0x6eed4e9da4d94a4b)

    # x ^= (x >> 32) >> (x >> 60)

    # x = trunc(x * 0x6eed4e9da4d94a4b)
    # x ^= (x >> 32) >> (x >> 60)

    return x

def f2(x):
    x = trunc(x * 0x6eed4e9da4d94a4b)
    x ^= x >> 32

    x = trunc(x * 0x6eed4e9da4d94a4b)
    x ^= x >> 32

    # x = trunc(x * 0x6eed4e9da4d94a4b)
    # x ^= x >> 32

    return x

# The cache should be unnecessary since
# repeats are handled already, but
# this wasn't always the case.
seen = {}
def f3(x):
    # Yes, yes, Python's `random` isn't actually perfectly random.
    return seen.setdefault(x, random.randrange(2**64))

display()