enc 0.19.0

This library aids in processing encoded data.
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
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

/// Decodes the `last_block` of 1 byte into the `target`.
///
/// Decoding 1 byte produces 6 bits, which is expanded to 1 byte.
/// The last 2 bits of output are set to 0.
/// Returns the number of decoded bytes. (1)
///
/// # Safety
/// The `last_block` length must be exactly 1.
/// The `target` length must be exactly 1.
pub unsafe fn decode_block_last_1(
    table: &[u8; 256],
    last_block: &[u8],
    target: &mut [u8],
) -> usize {
    debug_assert_eq!(last_block.len(), 1);
    debug_assert_eq!(target.len(), 1);

    let a: u32 = unsafe { *table.get_unchecked(*last_block.get_unchecked(0) as usize) } as u32;
    let bits: u32 = a << 2;
    unsafe { *target.get_unchecked_mut(0) = bits as u8 };

    1
}

#[cfg(test)]
mod tests {
    use crate::base_64::decode::decode_block_last_1::decode_block_last_1;
    use crate::base_64::decode::decoding_table::DecodingTable;

    #[test]
    fn fn_decode_block() {
        let test_cases: &[(&str, &[u8])] = &[
            ("A", b"\x00"),
            ("Z", b"\x64"),
            ("a", b"\x68"),
            ("z", b"\xCC"),
            ("/", b"\xFC"),
        ];

        let table: DecodingTable = DecodingTable::default();
        let table: &[u8; 256] = table.decoding_table();
        for (data, expected) in test_cases {
            let mut target: [u8; 1] = [0u8; 1];
            let result: usize = unsafe { decode_block_last_1(table, data.as_bytes(), &mut target) };
            assert_eq!(result, 1);
            assert_eq!(&target[..1], *expected, "data={}", *data);
        }
    }
}