bintext 0.1.3

Encode and decodes binary encoded text into aligned binary blobs using SIMD
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
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242

//! Hex encoding and decoding

use std::error::Error;
use std::fmt;

mod avx2;
mod fallback;
mod sse2;

mod support;
mod tests;

/// Invalid nibble
const I: u8 = 255;

/// Hex nibble decoding table
#[rustfmt::skip]
const HEX_NIBBLE_DECODE: [u8; 256] = [
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
  0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9,  I,  I,  I,  I,  I,  I,
    I, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I,
    I,   I,   I,   I,   I,   I,   I,   I,   I,   I,  I,  I,  I,  I,  I,  I
];

// Inverted to make error handle works
const N: u8 = 0;
const HEX_DECODE_64LUT_X30_1: i64 = i64::from_le_bytes([!0x8, !0x9, N, N, N, N, N, N]); // [0-9]
const HEX_DECODE_64LUT_X30_0: i64 =
    i64::from_le_bytes([!0x0, !0x1, !0x2, !0x3, !0x4, !0x5, !0x6, !0x7]);
const HEX_DECODE_64LUT_AZ: i64 = i64::from_le_bytes([N, !0xa, !0xb, !0xc, !0xd, !0xe, !0xf, N]); // [a-z] [A-Z]

#[rustfmt::skip]
const HEX_ENCODE: [u8; 512] = 
    *b"000102030405060708090a0b0c0d0e0f\
       101112131415161718191a1b1c1d1e1f\
       202122232425262728292a2b2c2d2e2f\
       303132333435363738393a3b3c3d3e3f\
       404142434445464748494a4b4c4d4e4f\
       505152535455565758595a5b5c5d5e5f\
       606162636465666768696a6b6c6d6e6f\
       707172737475767778797a7b7c7d7e7f\
       808182838485868788898a8b8c8d8e8f\
       909192939495969798999a9b9c9d9e9f\
       a0a1a2a3a4a5a6a7a8a9aaabacadaeaf\
       b0b1b2b3b4b5b6b7b8b9babbbcbdbebf\
       c0c1c2c3c4c5c6c7c8c9cacbcccdcecf\
       d0d1d2d3d4d5d6d7d8d9dadbdcdddedf\
       e0e1e2e3e4e5e6e7e8e9eaebecedeeef\
       f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff";

// (L) least (M) more significant mibble masks
const MN_MASK: i32 = 0xF0F0F0F0u32 as i32;
const LN_MASK: i32 = 0x0F0F0F0F;
const HEX_ENCODE_64LUT_1: i64 = i64::from_be_bytes(*b"fedcba98");
const HEX_ENCODE_64LUT_0: i64 = i64::from_be_bytes(*b"76543210");

/// Allocates `Vec<u8>` of a given length with uninitialized data
#[inline(always)]
fn alloc(length: usize) -> Vec<u8> {
    let mut v = Vec::with_capacity(length);
    unsafe {
        v.set_len(length);
    }
    v
}

#[derive(Debug)]
pub enum DecodeError {
    OddLength,
    InvalidCharAt(usize),
    /// Offset was less than alignment (it needs to be at least equal or greater)
    BadOffset,
}

impl fmt::Display for DecodeError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        use DecodeError::*;
        match self {
            OddLength => write!(f, "odd length, hexadecimal strings should be always even"),
            InvalidCharAt(pos) => write!(f, "invalid hexadecimal char at {}", pos),
            BadOffset => write!(
                f,
                "not enough offset was given, it needs to be equal or greater than alignment"
            ),
        }
    }
}

impl Error for DecodeError {}

/// Fast hex string decode. No error description is provided
#[no_mangle]
pub fn decode_noerr(input: &str) -> Result<Vec<u8>, ()> {
    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    if is_x86_feature_detected!("avx2") {
        return unsafe { avx2::decode(input).map_err(|_| ()) };
    } else if is_x86_feature_detected!("ssse3") {
        return unsafe { sse2::decode(input).map_err(|_| ()) };
    }

    fallback::decode(input).map_err(|_| ())
}

/// Decodes an hex string with all error messages, useful when dealing with
/// recoverable code logic or when a error message is required to facilitate
/// user action.
#[no_mangle]
pub fn decode(input: &str) -> Result<Vec<u8>, DecodeError> {
    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    if is_x86_feature_detected!("avx2") {
        return unsafe { avx2::decode(input) };
    } else if is_x86_feature_detected!("ssse3") {
        return unsafe { sse2::decode(input) };
    }

    fallback::decode(input)
}

/// Decodes a hex str starting from `offset` with a given `align`ment.
///
/// The input str will no longer be a valid utf8 string, a byte slice
/// will be returned upon success matching the alignment requirements
///
/// **NOTE** `offset` must be greater or equal to `align`
///
/// ```rust
/// // Padding of 8 (suppose it was read form a file)
/// let mut hex = "--------a1f7d5e8d14f0f76".to_string();
///
/// unsafe {
///     // Decode with padding of 8 and alignment of 8
///     let slice = bintext::hex::decode_aligned(&mut hex, 8, 8).unwrap();
///     // Data is aligned so you can safely do this:
///     let slice: &[u64] = std::slice::from_raw_parts(
///        slice.as_ptr() as *const _,
///        slice.len() / std::mem::size_of::<u64>()
///     );
/// }
/// ```
#[no_mangle]
pub unsafe fn decode_aligned(
    input: &mut str,
    offset: usize,
    align: usize,
) -> Result<&mut [u8], DecodeError> {
    use DecodeError::*;

    // Safe only when if offset is greater or equal than the alignment requirement
    if align > 1 && offset < align {
        Err(BadOffset)?
    }

    let bytes = input.as_bytes_mut();
    let len = bytes.len();
    if (len - offset) & 1 != 0 {
        Err(OddLength)?
    }

    let a = bytes.as_ptr().align_offset(align);
    let output = std::slice::from_raw_parts_mut(bytes.as_mut_ptr().add(a), (len - offset) / 2);

    let input = &bytes[offset..];

    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    if is_x86_feature_detected!("avx2") {
        return avx2::decode_noalloc(input, output).map(|_| output);
    } else if is_x86_feature_detected!("ssse3") {
        return sse2::decode_noalloc(input, output).map(|_| output);
    }

    fallback::decode_noalloc(input, output)?;
    Ok(output)
}

/// Decodes an hex string without allocating any memory
#[no_mangle]
pub fn decode_noalloc(input: &str, output: &mut [u8]) -> Result<(), DecodeError> {
    use DecodeError::*;

    let c = input.len();
    if c & 1 != 0 {
        Err(OddLength)?
    }

    let input = input.as_bytes();

    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    if is_x86_feature_detected!("avx2") {
        return unsafe { avx2::decode_noalloc(input, output) };
    } else if is_x86_feature_detected!("ssse3") {
        return unsafe { sse2::decode_noalloc(input, output) };
    }

    fallback::decode_noalloc(input, output)
}

///////////////////////////////////////////////////////////////////////////////

#[no_mangle]
pub fn encode(input: &[u8]) -> String {
    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    if is_x86_feature_detected!("avx2") {
        return unsafe { avx2::encode(input) };
    } else if is_x86_feature_detected!("ssse3") {
        return unsafe { sse2::encode(input) };
    }

    fallback::encode(input)
}

#[cfg(test)]
mod tests_extra {
    const SAMPLES_ALIGNED: [(&'static [u8], &'static str, usize, usize, usize); 5] = [
        (b"\x02\x03\x04\x05", "----02030405", 4, 4, 0),
        (b"\x02\x03\x04\x05", "#----02030405", 5, 4, 0),
        (b"\x02\x03\x04\x05", "#--02030405", 3, 2, 0),
        (b"\x02\x03\x04\x05", "02030405", 0, 1, 0),
        (b"\x02\x03\x04\x05", "...#----02030405", 5, 4, 3),
    ];

    #[test]
    fn decoding_aligned() {
        for (expected, input, offset, align, start) in SAMPLES_ALIGNED.iter() {
            let mut v = input[*start..].to_string();
            let v = unsafe { super::decode_aligned(&mut v, *offset, *align).unwrap() };
            assert_eq!(v, *expected);
            assert_eq!(v.as_ptr().align_offset(*align), 0);
        }
    }
}