      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
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403

    //! An implementation of SipHash.

    #![allow(deprecated)] // the types in this module are deprecated

    use marker::PhantomData;
    use ptr;
    use cmp;
    use mem;

    /// An implementation of SipHash 1-3.
    ///
    /// This is currently the default hashing function used by standard library
    /// (e.g., `collections::HashMap` uses it by default).
    ///
    /// See: <https://131002.net/siphash>
    #[unstable(feature = "hashmap_internals", issue = "0")]
    #[rustc_deprecated(since = "1.13.0",
                       reason = "use `std::collections::hash_map::DefaultHasher` instead")]
    #[derive(Debug, Clone, Default)]
    #[doc(hidden)]
    pub struct SipHasher13 {
        hasher: Hasher<Sip13Rounds>,
    }

    /// An implementation of SipHash 2-4.
    ///
    /// See: <https://131002.net/siphash/>
    #[unstable(feature = "hashmap_internals", issue = "0")]
    #[rustc_deprecated(since = "1.13.0",
                       reason = "use `std::collections::hash_map::DefaultHasher` instead")]
    #[derive(Debug, Clone, Default)]
    struct SipHasher24 {
        hasher: Hasher<Sip24Rounds>,
    }

    /// An implementation of SipHash 2-4.
    ///
    /// See: <https://131002.net/siphash/>
    ///
    /// SipHash is a general-purpose hashing function: it runs at a good
    /// speed (competitive with Spooky and City) and permits strong _keyed_
    /// hashing. This lets you key your hashtables from a strong RNG, such as
    /// [`rand::os::OsRng`](https://doc.rust-lang.org/rand/rand/os/struct.OsRng.html).
    ///
    /// Although the SipHash algorithm is considered to be generally strong,
    /// it is not intended for cryptographic purposes. As such, all
    /// cryptographic uses of this implementation are _strongly discouraged_.
    #[stable(feature = "rust1", since = "1.0.0")]
    #[rustc_deprecated(since = "1.13.0",
                       reason = "use `std::collections::hash_map::DefaultHasher` instead")]
    #[derive(Debug, Clone, Default)]
    pub struct SipHasher(SipHasher24);

    #[derive(Debug)]
    struct Hasher<S: Sip> {
        k0: u64,
        k1: u64,
        length: usize, // how many bytes we've processed
        state: State, // hash State
        tail: u64, // unprocessed bytes le
        ntail: usize, // how many bytes in tail are valid
        _marker: PhantomData<S>,
    }

    #[derive(Debug, Clone, Copy)]
    #[repr(C)]
    struct State {
        // v0, v2 and v1, v3 show up in pairs in the algorithm,
        // and simd implementations of SipHash will use vectors
        // of v02 and v13. By placing them in this order in the struct,
        // the compiler can pick up on just a few simd optimizations by itself.
        v0: u64,
        v2: u64,
        v1: u64,
        v3: u64,
    }

    macro_rules! compress {
        ($state:expr) => ({
            compress!($state.v0, $state.v1, $state.v2, $state.v3)
        });
        ($v0:expr, $v1:expr, $v2:expr, $v3:expr) =>
        ({
            $v0 = $v0.wrapping_add($v1); $v1 = $v1.rotate_left(13); $v1 ^= $v0;
            $v0 = $v0.rotate_left(32);
            $v2 = $v2.wrapping_add($v3); $v3 = $v3.rotate_left(16); $v3 ^= $v2;
            $v0 = $v0.wrapping_add($v3); $v3 = $v3.rotate_left(21); $v3 ^= $v0;
            $v2 = $v2.wrapping_add($v1); $v1 = $v1.rotate_left(17); $v1 ^= $v2;
            $v2 = $v2.rotate_left(32);
        });
    }

    /// Loads an integer of the desired type from a byte stream, in LE order. Uses
    /// `copy_nonoverlapping` to let the compiler generate the most efficient way
    /// to load it from a possibly unaligned address.
    ///
    /// Unsafe because: unchecked indexing at i..i+size_of(int_ty)
    macro_rules! load_int_le {
        ($buf:expr, $i:expr, $int_ty:ident) =>
        ({
           debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
           let mut data = 0 as $int_ty;
           ptr::copy_nonoverlapping($buf.get_unchecked($i),
                                    &mut data as *mut _ as *mut u8,
                                    mem::size_of::<$int_ty>());
           data.to_le()
        });
    }

    /// Loads an u64 using up to 7 bytes of a byte slice.
    ///
    /// Unsafe because: unchecked indexing at start..start+len
    #[inline]
    unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
        debug_assert!(len < 8);
        let mut i = 0; // current byte index (from LSB) in the output u64
        let mut out = 0;
        if i + 3 < len {
            out = load_int_le!(buf, start + i, u32) as u64;
            i += 4;
        }
        if i + 1 < len {
            out |= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
            i += 2
        }
        if i < len {
            out |= (*buf.get_unchecked(start + i) as u64) << (i * 8);
            i += 1;
        }
        debug_assert_eq!(i, len);
        out
    }

    impl SipHasher {
        /// Creates a new `SipHasher` with the two initial keys set to 0.
        #[inline]
        #[stable(feature = "rust1", since = "1.0.0")]
        #[rustc_deprecated(since = "1.13.0",
                           reason = "use `std::collections::hash_map::DefaultHasher` instead")]
        pub fn new() -> SipHasher {
            SipHasher::new_with_keys(0, 0)
        }

        /// Creates a `SipHasher` that is keyed off the provided keys.
        #[inline]
        #[stable(feature = "rust1", since = "1.0.0")]
        #[rustc_deprecated(since = "1.13.0",
                           reason = "use `std::collections::hash_map::DefaultHasher` instead")]
        pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher {
            SipHasher(SipHasher24 {
                hasher: Hasher::new_with_keys(key0, key1)
            })
        }
    }

    impl SipHasher13 {
        /// Creates a new `SipHasher13` with the two initial keys set to 0.
        #[inline]
        #[unstable(feature = "hashmap_internals", issue = "0")]
        #[rustc_deprecated(since = "1.13.0",
                           reason = "use `std::collections::hash_map::DefaultHasher` instead")]
        pub fn new() -> SipHasher13 {
            SipHasher13::new_with_keys(0, 0)
        }

        /// Creates a `SipHasher13` that is keyed off the provided keys.
        #[inline]
        #[unstable(feature = "hashmap_internals", issue = "0")]
        #[rustc_deprecated(since = "1.13.0",
                           reason = "use `std::collections::hash_map::DefaultHasher` instead")]
        pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
            SipHasher13 {
                hasher: Hasher::new_with_keys(key0, key1)
            }
        }
    }

    impl<S: Sip> Hasher<S> {
        #[inline]
        fn new_with_keys(key0: u64, key1: u64) -> Hasher<S> {
            let mut state = Hasher {
                k0: key0,
                k1: key1,
                length: 0,
                state: State {
                    v0: 0,
                    v1: 0,
                    v2: 0,
                    v3: 0,
                },
                tail: 0,
                ntail: 0,
                _marker: PhantomData,
            };
            state.reset();
            state
        }

        #[inline]
        fn reset(&mut self) {
            self.length = 0;
            self.state.v0 = self.k0 ^ 0x736f6d6570736575;
            self.state.v1 = self.k1 ^ 0x646f72616e646f6d;
            self.state.v2 = self.k0 ^ 0x6c7967656e657261;
            self.state.v3 = self.k1 ^ 0x7465646279746573;
            self.ntail = 0;
        }

        // Specialized write function that is only valid for buffers with len <= 8.
        // It's used to force inlining of write_u8 and write_usize, those would normally be inlined
        // except for composite types (that includes slices and str hashing because of delimiter).
        // Without this extra push the compiler is very reluctant to inline delimiter writes,
        // degrading performance substantially for the most common use cases.
        #[inline]
        fn short_write(&mut self, msg: &[u8]) {
            debug_assert!(msg.len() <= 8);
            let length = msg.len();
            self.length += length;

            let needed = 8 - self.ntail;
            let fill = cmp::min(length, needed);
            if fill == 8 {
                self.tail = unsafe { load_int_le!(msg, 0, u64) };
            } else {
                self.tail |= unsafe { u8to64_le(msg, 0, fill) } << (8 * self.ntail);
                if length < needed {
                    self.ntail += length;
                    return;
                }
            }
            self.state.v3 ^= self.tail;
            S::c_rounds(&mut self.state);
            self.state.v0 ^= self.tail;

            // Buffered tail is now flushed, process new input.
            self.ntail = length - needed;
            self.tail = unsafe { u8to64_le(msg, needed, self.ntail) };
        }
    }

    #[stable(feature = "rust1", since = "1.0.0")]
    impl super::Hasher for SipHasher {
        #[inline]
        fn write(&mut self, msg: &[u8]) {
            self.0.hasher.write(msg)
        }

        #[inline]
        fn finish(&self) -> u64 {
            self.0.hasher.finish()
        }
    }

    #[unstable(feature = "hashmap_internals", issue = "0")]
    impl super::Hasher for SipHasher13 {
        #[inline]
        fn write(&mut self, msg: &[u8]) {
            self.hasher.write(msg)
        }

        #[inline]
        fn finish(&self) -> u64 {
            self.hasher.finish()
        }
    }

    impl<S: Sip> super::Hasher for Hasher<S> {
        // see short_write comment for explanation
        #[inline]
        fn write_usize(&mut self, i: usize) {
            let bytes = unsafe {
                ::slice::from_raw_parts(&i as *const usize as *const u8, mem::size_of::<usize>())
            };
            self.short_write(bytes);
        }

        // see short_write comment for explanation
        #[inline]
        fn write_u8(&mut self, i: u8) {
            self.short_write(&[i]);
        }

        #[inline]
        fn write(&mut self, msg: &[u8]) {
            let length = msg.len();
            self.length += length;

            let mut needed = 0;

            if self.ntail != 0 {
                needed = 8 - self.ntail;
                self.tail |= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << 8 * self.ntail;
                if length < needed {
                    self.ntail += length;
                    return
                } else {
                    self.state.v3 ^= self.tail;
                    S::c_rounds(&mut self.state);
                    self.state.v0 ^= self.tail;
                    self.ntail = 0;
                }
            }

            // Buffered tail is now flushed, process new input.
            let len = length - needed;
            let left = len & 0x7;

            let mut i = needed;
            while i < len - left {
                let mi = unsafe { load_int_le!(msg, i, u64) };

                self.state.v3 ^= mi;
                S::c_rounds(&mut self.state);
                self.state.v0 ^= mi;

                i += 8;
            }

            self.tail = unsafe { u8to64_le(msg, i, left) };
            self.ntail = left;
        }

        #[inline]
        fn finish(&self) -> u64 {
            let mut state = self.state;

            let b: u64 = ((self.length as u64 & 0xff) << 56) | self.tail;

            state.v3 ^= b;
            S::c_rounds(&mut state);
            state.v0 ^= b;

            state.v2 ^= 0xff;
            S::d_rounds(&mut state);

            state.v0 ^ state.v1 ^ state.v2 ^ state.v3
        }
    }

    impl<S: Sip> Clone for Hasher<S> {
        #[inline]
        fn clone(&self) -> Hasher<S> {
            Hasher {
                k0: self.k0,
                k1: self.k1,
                length: self.length,
                state: self.state,
                tail: self.tail,
                ntail: self.ntail,
                _marker: self._marker,
            }
        }
    }

    impl<S: Sip> Default for Hasher<S> {
        /// Creates a `Hasher<S>` with the two initial keys set to 0.
        #[inline]
        fn default() -> Hasher<S> {
            Hasher::new_with_keys(0, 0)
        }
    }

    #[doc(hidden)]
    trait Sip {
        fn c_rounds(_: &mut State);
        fn d_rounds(_: &mut State);
    }

    #[derive(Debug, Clone, Default)]
    struct Sip13Rounds;

    impl Sip for Sip13Rounds {
        #[inline]
        fn c_rounds(state: &mut State) {
            compress!(state);
        }

        #[inline]
        fn d_rounds(state: &mut State) {
            compress!(state);
            compress!(state);
            compress!(state);
        }
    }

    #[derive(Debug, Clone, Default)]
    struct Sip24Rounds;

    impl Sip for Sip24Rounds {
        #[inline]
        fn c_rounds(state: &mut State) {
            compress!(state);
            compress!(state);
        }

        #[inline]
        fn d_rounds(state: &mut State) {
            compress!(state);
            compress!(state);
            compress!(state);
            compress!(state);
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)