ct_codecs/
hex.rs

1use crate::error::*;
2use crate::{Decoder, Encoder};
3
4pub struct Hex;
5
6impl Encoder for Hex {
7    #[inline]
8    fn encoded_len(bin_len: usize) -> Result<usize, Error> {
9        bin_len.checked_mul(2).ok_or(Error::Overflow)
10    }
11
12    fn encode<IN: AsRef<[u8]>>(hex: &mut [u8], bin: IN) -> Result<&[u8], Error> {
13        let bin = bin.as_ref();
14        let bin_len = bin.len();
15        let hex_maxlen = hex.len();
16        if hex_maxlen < bin_len.checked_shl(1).ok_or(Error::Overflow)? {
17            return Err(Error::Overflow);
18        }
19        for (i, v) in bin.iter().enumerate() {
20            let (b, c) = ((v >> 4) as u16, (v & 0xf) as u16);
21            let x = (((87 + c + (((c.wrapping_sub(10)) >> 8) & !38)) as u8) as u16) << 8
22                | ((87 + b + (((b.wrapping_sub(10)) >> 8) & !38)) as u8) as u16;
23            hex[i * 2] = x as u8;
24            hex[i * 2 + 1] = (x >> 8) as u8;
25        }
26        Ok(&hex[..bin_len * 2])
27    }
28}
29
30impl Decoder for Hex {
31    fn decode<'t, IN: AsRef<[u8]>>(
32        bin: &'t mut [u8],
33        hex: IN,
34        ignore: Option<&[u8]>,
35    ) -> Result<&'t [u8], Error> {
36        let hex = hex.as_ref();
37        let bin_maxlen = bin.len();
38        let mut bin_pos = 0;
39        let mut state = false;
40        let mut c_acc = 0;
41        for &c in hex {
42            let c_num = c ^ 48;
43            let c_num0 = ((c_num as u16).wrapping_sub(10) >> 8) as u8;
44            let c_alpha = (c & !32).wrapping_sub(55);
45            let c_alpha0 = (((c_alpha as u16).wrapping_sub(10)
46                ^ ((c_alpha as u16).wrapping_sub(16)))
47                >> 8) as u8;
48            if (c_num0 | c_alpha0) == 0 {
49                match ignore {
50                    Some(ignore) if ignore.contains(&c) => continue,
51                    _ => return Err(Error::InvalidInput),
52                };
53            }
54            let c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
55            if bin_pos >= bin_maxlen {
56                return Err(Error::Overflow);
57            }
58            if !state {
59                c_acc = c_val << 4;
60            } else {
61                bin[bin_pos] = c_acc | c_val;
62                bin_pos += 1;
63            }
64            state = !state;
65        }
66        if state {
67            return Err(Error::InvalidInput);
68        }
69        Ok(&bin[..bin_pos])
70    }
71}
72
73#[cfg(feature = "std")]
74#[test]
75fn test_hex() {
76    let bin = [1u8, 5, 11, 15, 19, 131];
77    let hex = Hex::encode_to_string(bin).unwrap();
78    let expected = "01050b0f1383";
79    assert_eq!(hex, expected);
80    let bin2 = Hex::decode_to_vec(&hex, None).unwrap();
81    assert_eq!(bin, &bin2[..]);
82}
83
84#[test]
85fn test_hex_no_std() {
86    let bin = [1u8, 5, 11, 15, 19, 131];
87    let expected = "01050b0f1383";
88    let mut hex = [0u8; 12];
89    let hex = Hex::encode_to_str(&mut hex, bin).unwrap();
90    assert_eq!(&hex, &expected);
91    let mut bin2 = [0u8; 6];
92    let bin2 = Hex::decode(&mut bin2, hex, None).unwrap();
93    assert_eq!(bin, bin2);
94}
ct_codecs/hex.rs

ct_codecs/
hex.rs
