Z-Order Curve

zorder.groovy

#!/usr/bin/env groovy

ztoc = { int d, int z ->
    if (0 == d) {
        return []
    }

    if (1 == d) {
        return [z]
    }

    def m = 1
    def c = [0]*d
    while (z) {
        for (int i = 0; i < c.size(); i++) {
            c[i] |= m & z
            z >>= 1
        }
        z <<= 1
        m <<= 1
    }
    return c
}

ctoz = { List coord ->
    def c = [] + coord
    def z = 0
    def k = 0
    while (c && c.any()) {
        for (int i = 0; i < c.size(); i++) {
            z |= (1 & c[i]) << k 
            c[i] >>= 1
            k++
        }
    }
    return z
}

switch (args[0]) {
    case 'ztoc' -> println ztoc(args[1] as int, args[2] as int).join(' ')
    case 'ctoz' -> println ctoz(args[1..-1].collect { it as int })
    default -> assert false
}

zorder.py

#!/usr/bin/env python3
import sys

def ztoc(d, z):
    if 0 == d:
        return []
    
    if 1 == d:
        return [z]

    m = 1
    c = [0]*d
    while z:
        for i in range(len(c)):
            c[i] |= m & z
            z >>= 1
        z <<= 1
        m <<= 1
    return c

def ctoz(c):
    c = c.copy()
    z = 0
    k = 0
    while c and any(c):
        for i in range(len(c)):
            z |= (1 & c[i]) << k
            c[i] >>= 1
            k += 1
    return z

if __name__ == "__main__":
    args = sys.argv[1:]
    if 'ztoc' == args[0]:
        print(ztoc(int(args[1]), int(args[2])))
    elif 'ctoz' == args[0]:
        print(ctoz([int(i) for i in args[1:]]))
    else:
        assert False