luaur-vm 0.1.1

The Luau register virtual machine and standard library (Rust).
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

use crate::records::lua_node::LuaNode;
use crate::records::lua_table::LuaTable;

#[allow(non_snake_case)]
pub(crate) unsafe fn hashint(t: *const LuaTable, n: i64) -> *mut LuaNode {
    // static_assert(sizeof(n) == sizeof(unsigned int) * 2, "expected a 8-byte integer");
    let mut i: [u32; 2] = [0; 2];
    core::ptr::copy_nonoverlapping(&n as *const i64 as *const u8, i.as_mut_ptr() as *mut u8, 8);

    let mut h1 = i[0];
    let mut h2 = i[1];

    // finalizer from MurmurHash64B
    const M: u32 = 0x5bd1e995;

    h1 ^= h2 >> 18;
    h1 = h1.wrapping_mul(M);
    h2 ^= h1 >> 22;
    h2 = h2.wrapping_mul(M);
    h1 ^= h2 >> 17;
    h1 = h1.wrapping_mul(M);
    h2 ^= h1 >> 19;
    h2 = h2.wrapping_mul(M);

    // ... truncated to 32-bit output (normally hash is equal to (uint64_t(h1) << 32) | h2, but we only really need the lower 32-bit half)
    // We cast h2 to i32 to satisfy the lmod! macro's expectation of signed bitwise operands in the VM's specific lmod implementation.
    crate::macros::gnode::gnode!(
        t,
        crate::macros::lmod::lmod!(h2 as i32, crate::macros::sizenode::sizenode!(t)) as usize
    )
}