1use crate::limb::Limb;
2
3const fn parse_digit(d: u8) -> u8 {
4 match d.to_ascii_lowercase() {
5 b'0'..=b'9' => d - b'0',
6 b'a'..=b'f' => d - b'a' + 10,
7 _ => panic!(),
8 }
9}
10
11// TODO: this would be nicer as a trait, but currently traits don't support const functions
12pub const fn limbs_from_hex<const LIMBS: usize>(hex: &str) -> [Limb; LIMBS] {
13 let hex: &[u8] = hex.as_bytes();
14 let mut limbs: [u64; LIMBS] = [0; LIMBS];
15 let limb_nibbles: usize = core::mem::size_of::<Limb>() * 2;
16 let mut i: usize = 0;
17
18 while i < hex.len() {
19 let char: u8 = hex[hex.len() - 1 - i];
20 let val: u8 = parse_digit(char);
21 limbs[i / limb_nibbles] |= (val as Limb) << ((i % limb_nibbles) * 4);
22 i += 1;
23 }
24
25 limbs
26}
27