zorder.rs

use std::arch::asm;

#[inline(always)]
fn pdep_u64(x: u64, mask: u64) -> u64 {
    let mut _rv: u64;
    unsafe {
        asm !{
            "pdep {out}, {x}, {mask}",
            out = out(reg) _rv,
            x = in(reg) x,
            mask = in(reg) mask,
            options(pure, nomem, nostack),
        }
    }
    _rv
}

#[inline(always)]
fn pext_u64(x: u64, mask: u64) -> u64 {
    let mut _rv: u64;
    unsafe {
        asm !{
            "pext {out}, {x}, {mask}",
            out = out(reg) _rv,
            x = in(reg) x,
            mask = in(reg) mask,
            options(pure, nomem, nostack),
        }
    }
    _rv
}

const MASK_MOD2: u64 = 0x5555555555555555;

#[inline(never)]
pub fn zorder_to_xy(z: u64)->(u32, u32) {
    let x = pext_u64(z, MASK_MOD2) as u32;
    let y = pext_u64(z >> 1, MASK_MOD2) as u32;
    (x, y)
}

#[inline(never)]
pub fn zorder_from_xy(x: u32, y: u32) -> u64 {
    let x = pdep_u64(x as u64, MASK_MOD2);
    let y = pdep_u64(y as u64, MASK_MOD2);
    x | (y << 1)
}

const MASK_MOD3: u64 = 0x1249249249249249;

#[inline(never)]
pub fn zorder_to_xyz(z: u64)->(u32, u32, u32) {
    let x = pext_u64(z, MASK_MOD3) as u32;
    let y = pext_u64(z >> 1, MASK_MOD3) as u32;
    let z = pext_u64(z >> 2, MASK_MOD3) as u32;
    (x, y, z)
}

#[inline(never)]
pub fn zorder_from_xyz(x: u32, y: u32, z: u32) -> u64 {
    let x = pdep_u64(x as u64, MASK_MOD3);
    let y = pdep_u64(y as u64, MASK_MOD3);
    let z = pdep_u64(z as u64, MASK_MOD3);
    x | (y << 1) | (z << 2)
}

fn main() {
    println!("(25, 33) -> {:?}", zorder_from_xy(25, 33));
    println!("2371 -> {:?}", zorder_to_xy(2371));
    println!("(25, 33, 41) -> {:?}", zorder_from_xyz(25, 33, 41));
    println!("203271 -> {:?}", zorder_to_xyz(203271));
    // println!("{}", zorder64inv(3));
}

zorder.s

zorder_to_xy:
        movabs  rcx, 0x5555555555555555
        pext    rax, rcx, rdi
        shr     rdi
        pext    rdx, rcx, rdi
        ret

zorder_from_xy:
        mov     eax, edi
        movabs  rcx, 0x5555555555555555
        pdep    rdx, rcx, rax
        mov     esi, esi
        pdep    rax, rcx, rsi
        add     rax, rax
        or      rax, rdx
        ret

zorder_to_xyz:
        movabs  rax, 0x1249249249249249
        pext    rcx, rax, rdi
        mov     rdx, rdi
        shr     rdx
        pext    rsi, rax, rdx
        shr     rdi, 2
        pext    rdx, rax, rdi
        shl     rsi, 32
        mov     eax, ecx
        or      rax, rsi
        ret

zorder_from_xyz:
        mov     eax, edi
        movabs  rcx, 0x1249249249249249
        pdep    rdi, rcx, rax
        mov     eax, esi
        pdep    rsi, rcx, rax
        mov     edx, edx
        pdep    rax, rcx, rdx
        add     rsi, rsi
        or      rsi, rdi
        shl     rax, 2
        or      rax, rsi
        ret