Hasher.C 22.3 KB
Newer Older
1 2 3 4
/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
OpenFOAM bot's avatar
OpenFOAM bot committed
5
    \\  /    A nd           | www.openfoam.com
6
     \\/     M anipulation  |
OpenFOAM bot's avatar
OpenFOAM bot committed
7
-------------------------------------------------------------------------------
OpenFOAM bot's avatar
OpenFOAM bot committed
8
    Copyright (C) 2011-2017 OpenFOAM Foundation
9 10 11 12
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

13 14 15 16
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
17 18 19 20 21 22 23

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
24
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
25 26 27 28 29

Description
    Hashing functions, mostly from Bob Jenkins
\*---------------------------------------------------------------------------*/

30
#include "Hasher.H"
31
#include "HasherInt.H"
32
#include "endian.H"
33

34 35 36 37
// Left-rotate a 32-bit value and carry by nBits
#define bitRotateLeft(x, nBits)  (((x) << (nBits)) | ((x) >> (32 - (nBits))))


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
// ----------------------------------------------------------------------------
// lookup3.c, by Bob Jenkins, May 2006, Public Domain.
//
// These are functions for producing 32-bit hashes for hash table lookup.
// hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
// are externally useful functions.  Routines to test the hash are included
// if SELF_TEST is defined.  You can use this free for any purpose.  It's in
// the public domain.  It has no warranty.
//
// You probably want to use hashlittle().  hashlittle() and hashbig()
// hash byte arrays.  hashlittle() is is faster than hashbig() on
// little-endian machines.  Intel and AMD are little-endian machines.
// On second thought, you probably want hashlittle2(), which is identical to
// hashlittle() except it returns two 32-bit hashes for the price of one.
// You could implement hashbig2() if you wanted but I haven't bothered here.
//
// If you want to find a hash of, say, exactly 7 integers, do
//   a = i1;  b = i2;  c = i3;
//   mix(a,b,c);
//   a += i4; b += i5; c += i6;
//   mix(a,b,c);
//   a += i7;
//   final(a,b,c);
// then use c as the hash value.  If you have a variable length array of
// 4-byte integers to hash, use hashword().  If you have a byte array (like
// a character string), use hashlittle().  If you have several byte arrays, or
// a mix of things, see the comments above hashlittle().
//
// Why is this so big?  I read 12 bytes at a time into 3 4-byte integers,
// then mix those integers.  This is fast (you can do a lot more thorough
// mixing with 12*3 instructions on 3 integers than you can with 3 instructions
// on 1 byte), but shoehorning those bytes into integers efficiently is messy.
// ----------------------------------------------------------------------------

// ----------------------------------------------------------------------------
// mix -- mix 3 32-bit values reversibly.
//
// This is reversible, so any information in (a,b,c) before mix_hash() is
// still in (a,b,c) after mix_hash().
//
// If four pairs of (a,b,c) inputs are run through mix_hash(), or through
// mix_hash() in reverse, there are at least 32 bits of the output that
// are sometimes the same for one pair and different for another pair.
// This was tested for:
// * pairs that differed by one bit, by two bits, in any combination
//   of top bits of (a,b,c), or in any combination of bottom bits of
//   (a,b,c).
// * "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
//   the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
//   is commonly produced by subtraction) look like a single 1-bit
//   difference.
// * the base values were pseudorandom, all zero but one bit set, or
//   all zero plus a counter that starts at zero.
//
// Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
// satisfy this are
//     4  6  8 16 19  4
//     9 15  3 18 27 15
//    14  9  3  7 17  3
// Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
// for "differ" defined as + with a one-bit base and a two-bit delta.  I
// used http://burtleburtle.net/bob/hash/avalanche.html to choose
// the operations, constants, and arrangements of the variables.
//
// This does not achieve avalanche.  There are input bits of (a,b,c)
// that fail to affect some output bits of (a,b,c), especially of a.  The
// most thoroughly mixed value is c, but it doesn't really even achieve
// avalanche in c.
//
// This allows some parallelism.  Read-after-writes are good at doubling
// the number of bits affected, so the goal of mixing pulls in the opposite
// direction as the goal of parallelism.  I did what I could.  Rotates
// seem to cost as much as shifts on every machine I could lay my hands
// on, and rotates are much kinder to the top and bottom bits, so I used
// rotates.
// ----------------------------------------------------------------------------

115 116 117 118 119 120 121 122
#define bitMixer(a, b, c)                                                      \
    {                                                                          \
        a -= c; a ^= bitRotateLeft(c, 4); c += b;                              \
        b -= a; b ^= bitRotateLeft(a, 6); a += c;                              \
        c -= b; c ^= bitRotateLeft(b, 8); b += a;                              \
        a -= c; a ^= bitRotateLeft(c,16); c += b;                              \
        b -= a; b ^= bitRotateLeft(a,19); a += c;                              \
        c -= b; c ^= bitRotateLeft(b, 4); b += a;                              \
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
// ----------------------------------------------------------------------------
// final -- final mixing of 3 32-bit values (a,b,c) into c
//
// Pairs of (a,b,c) values differing in only a few bits will usually
// produce values of c that look totally different.  This was tested for
// * pairs that differed by one bit, by two bits, in any combination
//   of top bits of (a,b,c), or in any combination of bottom bits of
//   (a,b,c).
// * "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
//   the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
//   is commonly produced by subtraction) look like a single 1-bit
//   difference.
// * the base values were pseudorandom, all zero but one bit set, or
//   all zero plus a counter that starts at zero.
//
// These constants passed:
//  14 11 25 16 4 14 24
//  12 14 25 16 4 14 24
// and these came close:
//   4  8 15 26 3 22 24
//  10  8 15 26 3 22 24
//  11  8 15 26 3 22 24
// ----------------------------------------------------------------------------

150 151 152 153 154 155 156 157 158
#define bitMixerFinal(a, b, c)                                                 \
    {                                                                          \
        c ^= b; c -= bitRotateLeft(b, 14);                                     \
        a ^= c; a -= bitRotateLeft(c, 11);                                     \
        b ^= a; b -= bitRotateLeft(a, 25);                                     \
        c ^= b; c -= bitRotateLeft(b, 16);                                     \
        a ^= c; a -= bitRotateLeft(c, 4);                                      \
        b ^= a; b -= bitRotateLeft(a, 14);                                     \
        c ^= b; c -= bitRotateLeft(b, 24);                                     \
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
// * * * * * * * * * * * * * * Static Functions  * * * * * * * * * * * * * * //

// ----------------------------------------------------------------------------
// hashlittle() -- hash a variable-length key into a 32-bit value
//   k       : the key (the unaligned variable-length array of bytes)
//   length  : the length of the key, counting by bytes
//   initval : can be any 4-byte value
// Returns a 32-bit value.  Every bit of the key affects every bit of
// the return value.  Two keys differing by one or two bits will have
// totally different hash values.
//
// The best hash table sizes are powers of 2.  There is no need to do
// mod a prime (mod is sooo slow!).  If you need less than 32 bits,
// use a bitmask.  For example, if you need only 10 bits, do
//   h = (h & hashmask(10));
// In which case, the hash table should have hashsize(10) elements.
//
// If you are hashing n strings (uint8_t **)k, do it like this:
//   for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h);
//
// By Bob Jenkins, 2006.  bob_jenkins@burtleburtle.net.  You may use this
// code any way you wish, private, educational, or commercial.  It's free.
//
// Use for hash table lookup, or anything where one collision in 2^^32 is
// acceptable.  Do NOT use for cryptographic purposes.
// ----------------------------------------------------------------------------

189
// Specialized little-endian code
190
#ifdef WM_LITTLE_ENDIAN
191
static unsigned jenkins_hashlittle
192 193 194
(
    const void *key,
    size_t length,
195
    unsigned initval
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
)
{
    uint32_t a, b, c;
    union { const void *ptr; size_t i; } u; // to cast key to (size_t) happily

    // Set up the internal state
    a = b = c = 0xdeadbeef + static_cast<uint32_t>(length) + initval;

    u.ptr = key;
    if ((u.i & 0x3) == 0)
    {
        // 32-bit chunks
        const uint32_t *k = reinterpret_cast<const uint32_t*>(key);

        // all but last block: aligned reads and affect 32 bits of (a,b,c)
        while (length > 12)
        {
            a += k[0];
            b += k[1];
            c += k[2];
            bitMixer(a,b,c);
            length -= 12;
            k += 3;
        }

        // handle the last (probably partial) block byte-wise
        const uint8_t *k8 = reinterpret_cast<const uint8_t*>(k);
        switch (length)
        {
            case 12: c += k[2]; b += k[1]; a += k[0]; break;
226 227 228
            case 11: c += static_cast<uint32_t>(k8[10]) << 16; [[fallthrough]];
            case 10: c += static_cast<uint32_t>(k8[9])  << 8;  [[fallthrough]];
            case 9 : c += k8[8];                               [[fallthrough]];
229
            case 8 : b += k[1]; a += k[0]; break;
230 231 232
            case 7 : b += static_cast<uint32_t>(k8[6]) << 16;  [[fallthrough]];
            case 6 : b += static_cast<uint32_t>(k8[5]) << 8;   [[fallthrough]];
            case 5 : b += k8[4];                               [[fallthrough]];
233
            case 4 : a += k[0]; break;
234 235
            case 3 : a += static_cast<uint32_t>(k8[2]) << 16;  [[fallthrough]];
            case 2 : a += static_cast<uint32_t>(k8[1]) << 8;   [[fallthrough]];
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
            case 1 : a += k8[0]; break;
            case 0 : return c;  // zero-length requires no mixing
        }
    }
    else if ((u.i & 0x1) == 0)
    {
        // 16-bit chunks
        const uint16_t *k = reinterpret_cast<const uint16_t*>(key);

        // all but last block: aligned reads and different mixing
        while (length > 12)
        {
            a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
            b += k[2] + (static_cast<uint32_t>(k[3]) << 16);
            c += k[4] + (static_cast<uint32_t>(k[5]) << 16);
            bitMixer(a,b,c);
            length -= 12;
            k += 6;
        }

        // handle the last (probably partial) block
        const uint8_t *k8 = reinterpret_cast<const uint8_t*>(k);
        switch (length)
        {
            case 12:
                c += k[4] + (static_cast<uint32_t>(k[5]) << 16);
                b += k[2] + (static_cast<uint32_t>(k[3]) << 16);
                a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
                break;
            case 11:
                c += static_cast<uint32_t>(k8[10]) << 16;
267
                [[fallthrough]];
268 269 270 271 272 273 274
            case 10:
                c += k[4];
                b += k[2] + (static_cast<uint32_t>(k[3]) << 16);
                a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
                break;
            case 9 :
                c += k8[8];
275
                [[fallthrough]];
276 277 278 279 280 281
            case 8 :
                b += k[2] + (static_cast<uint32_t>(k[3]) << 16);
                a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
                break;
            case 7 :
                b += static_cast<uint32_t>(k8[6]) << 16;
282
                [[fallthrough]];
283 284 285 286 287 288
            case 6 :
                b += k[2];
                a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
                break;
            case 5 :
                b += k8[4];
289
                [[fallthrough]];
290 291 292 293 294
            case 4 :
                a += k[0] + (static_cast<uint32_t>(k[1]) << 16);
                break;
            case 3 :
                a += static_cast<uint32_t>(k8[2]) << 16;
295
                [[fallthrough]];
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
            case 2 :
                a += k[0];
                break;
            case 1 :
                a += k8[0];
                break;
            case 0 : return c;     // zero-length requires no mixing
        }
    }
    else
    {
        const uint8_t *k = reinterpret_cast<const uint8_t*>(key);

        // all but the last block: affect some 32 bits of (a,b,c)
        while (length > 12)
        {
            a += k[0];
            a += static_cast<uint32_t>(k[1]) << 8;
            a += static_cast<uint32_t>(k[2]) << 16;
            a += static_cast<uint32_t>(k[3]) << 24;
            b += k[4];
            b += static_cast<uint32_t>(k[5]) << 8;
            b += static_cast<uint32_t>(k[6]) << 16;
            b += static_cast<uint32_t>(k[7]) << 24;
            c += k[8];
            c += static_cast<uint32_t>(k[9])  << 8;
            c += static_cast<uint32_t>(k[10]) << 16;
            c += static_cast<uint32_t>(k[11]) << 24;

            bitMixer(a,b,c);
            length -= 12;
            k += 12;
        }

        // last block: affect all 32 bits of (c)
        switch (length) // most case statements fall through
        {
333 334 335 336 337 338 339 340 341 342 343 344 345
            case 12: c += static_cast<uint32_t>(k[11]) << 24; [[fallthrough]];
            case 11: c += static_cast<uint32_t>(k[10]) << 16; [[fallthrough]];
            case 10: c += static_cast<uint32_t>(k[9]) << 8; [[fallthrough]];
            case 9 : c += k[8]; [[fallthrough]];

            case 8 : b += static_cast<uint32_t>(k[7]) << 24; [[fallthrough]];
            case 7 : b += static_cast<uint32_t>(k[6]) << 16; [[fallthrough]];
            case 6 : b += static_cast<uint32_t>(k[5]) << 8; [[fallthrough]];
            case 5 : b += k[4]; [[fallthrough]];

            case 4 : a += static_cast<uint32_t>(k[3]) << 24; [[fallthrough]];
            case 3 : a += static_cast<uint32_t>(k[2]) << 16; [[fallthrough]];
            case 2 : a += static_cast<uint32_t>(k[1]) << 8; [[fallthrough]];
346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365
            case 1 : a += k[0];
                break;

            case 0 : return c;
        }
    }

    bitMixerFinal(a,b,c);
    return c;
}
#endif


// ----------------------------------------------------------------------------
// hashbig():
// This is the same as hashword() on big-endian machines.  It is different
// from hashlittle() on all machines.  hashbig() takes advantage of
// big-endian byte ordering.
// ----------------------------------------------------------------------------
// specialized big-endian code
366
#ifdef WM_BIG_ENDIAN
367
static unsigned jenkins_hashbig
368 369 370
(
    const void *key,
    size_t length,
371
    unsigned initval
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
)
{
    uint32_t a, b, c;
    union { const void *ptr; size_t i; } u; // to cast key to (size_t) happily

    // Set up the internal state
    a = b = c = 0xdeadbeef + static_cast<uint32_t>(length) + initval;

    u.ptr = key;
    if ((u.i & 0x3) == 0)
    {
        // 32-bit chunks
        const uint32_t *k = reinterpret_cast<const uint32_t*>(key);

        // all but last block: aligned reads and affect 32 bits of (a,b,c)
        while (length > 12)
        {
            a += k[0];
            b += k[1];
            c += k[2];
            bitMixer(a,b,c);
            length -= 12;
            k += 3;
        }

        // handle the last (probably partial) block byte-wise
        const uint8_t *k8 = reinterpret_cast<const uint8_t*>(k);

        switch (length) // most the case statements fall through
        {
            case 12: c += k[2]; b += k[1]; a += k[0]; break;
403 404 405
            case 11: c += static_cast<uint32_t>(k8[10]) << 8; [[fallthrough]];
            case 10: c += static_cast<uint32_t>(k8[9]) << 16; [[fallthrough]];
            case 9 : c += static_cast<uint32_t>(k8[8]) << 24; [[fallthrough]];
406
            case 8 : b += k[1]; a += k[0]; break;
407 408 409
            case 7 : b += static_cast<uint32_t>(k8[6]) << 8;  [[fallthrough]];
            case 6 : b += static_cast<uint32_t>(k8[5]) << 16; [[fallthrough]];
            case 5 : b += static_cast<uint32_t>(k8[4]) << 24; [[fallthrough]];
410
            case 4 : a += k[0]; break;
411 412
            case 3 : a += static_cast<uint32_t>(k8[2]) << 8;  [[fallthrough]];
            case 2 : a += static_cast<uint32_t>(k8[1]) << 16; [[fallthrough]];
413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445
            case 1 : a += static_cast<uint32_t>(k8[0]) << 24; break;
            case 0 : return c;
        }
    }
    else
    {
        // need to read the key one byte at a time
        const uint8_t *k = reinterpret_cast<const uint8_t*>(key);

        // all but the last block: affect some 32 bits of (a,b,c)
        while (length > 12)
        {
            a += static_cast<uint32_t>(k[0]) << 24;
            a += static_cast<uint32_t>(k[1]) << 16;
            a += static_cast<uint32_t>(k[2]) << 8;
            a += static_cast<uint32_t>(k[3]);
            b += static_cast<uint32_t>(k[4]) << 24;
            b += static_cast<uint32_t>(k[5]) << 16;
            b += static_cast<uint32_t>(k[6]) << 8;
            b += static_cast<uint32_t>(k[7]);
            c += static_cast<uint32_t>(k[8]) << 24;
            c += static_cast<uint32_t>(k[9]) << 16;
            c += static_cast<uint32_t>(k[10]) << 8;
            c += static_cast<uint32_t>(k[11]);

            bitMixer(a,b,c);
            length -= 12;
            k += 12;
        }

        // last block: affect all 32 bits of (c)
        switch (length) // the case statements fall through
        {
446 447 448 449 450 451 452 453 454 455 456 457
            case 12: c += k[11]; [[fallthrough]];
            case 11: c += static_cast<uint32_t>(k[10]) << 8; [[fallthrough]];
            case 10: c += static_cast<uint32_t>(k[9]) << 16; [[fallthrough]];
            case 9 : c += static_cast<uint32_t>(k[8]) << 24; [[fallthrough]];
            case 8 : b += k[7]; [[fallthrough]];
            case 7 : b += static_cast<uint32_t>(k[6]) << 8; [[fallthrough]];
            case 6 : b += static_cast<uint32_t>(k[5]) << 16; [[fallthrough]];
            case 5 : b += static_cast<uint32_t>(k[4]) << 24; [[fallthrough]];
            case 4 : a += k[3]; [[fallthrough]];
            case 3 : a += static_cast<uint32_t>(k[2]) << 8; [[fallthrough]];
            case 2 : a += static_cast<uint32_t>(k[1]) << 16; [[fallthrough]];
            case 1 : a += static_cast<uint32_t>(k[0]) << 24; [[fallthrough]];
458 459 460 461 462 463 464 465 466 467 468
                break;
            case 0 : return c;
        }
    }

    bitMixerFinal(a,b,c);
    return c;
}
#endif


469
// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
470

471 472 473 474 475 476 477 478

unsigned Foam::Hasher
(
    const void *key,
    size_t length,
    unsigned initval
)
{
479 480 481 482
#if defined (WM_BIG_ENDIAN)
    return jenkins_hashbig(key, length, initval);
#elif defined (WM_LITTLE_ENDIAN)
    return jenkins_hashlittle(key, length, initval);
483
#else
484
    #error "Cannot determine WM_BIG_ENDIAN or WM_LITTLE_ENDIAN."
485 486 487 488
#endif
}


489 490 491 492 493 494 495 496 497 498 499
// ----------------------------------------------------------------------------
//  This works on all machines.  To be useful, it requires
//  -- that the key be an array of uint32_t's, and
//  -- that the length be the number of uint32_t's in the key
//
//  The function hashword() is identical to hashlittle() on little-endian
//  machines, and identical to hashbig() on big-endian machines,
//  except that the length has to be measured in uint32_ts rather than in
//  bytes.  hashlittle() is more complicated than hashword() only because
//  hashlittle() has to dance around fitting the key bytes into registers.
// ----------------------------------------------------------------------------
500
unsigned Foam::HasherInt
501 502 503
(
    const uint32_t *k,
    size_t length,
504
    unsigned seed
505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525
)
{
    uint32_t a, b, c;

    // Set up the internal state
    a = b = c = 0xdeadbeef + (static_cast<uint32_t>(length) << 2) + seed;

    // handle most of the key
    while (length > 3)
    {
        a += k[0];
        b += k[1];
        c += k[2];
        bitMixer(a,b,c);
        length -= 3;
        k += 3;
    }

    // handle the last 3 uint32_t's
    switch (length)  // all case statements fall through
    {
526 527
        case 3 : c += k[2]; [[fallthrough]];
        case 2 : b += k[1]; [[fallthrough]];
528 529
        case 1 : a += k[0];
            bitMixerFinal(a,b,c);
530
            [[fallthrough]];
531 532 533 534 535 536 537 538 539 540 541 542 543 544
        case 0 :  // case 0: nothing left to add
            break;
    }

    return c;
}


// ----------------------------------------------------------------------------
// hashword2() -- same as hashword(), but take two seeds and return two
// 32-bit values.  pc and pb must both be non-null, and *pc and *pb must
// both be initialized with seeds.  If you pass in (*pb)==0, the output
// (*pc) will be the same as the return value from hashword().
// ----------------------------------------------------------------------------
545
unsigned Foam::HasherDual
546 547 548
(
    const uint32_t *k,
    size_t length,
549 550
    unsigned& hash1,  // IN: seed OUT: primary hash value
    unsigned& hash2   // IN: more seed OUT: secondary hash value
551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572
)
{
    uint32_t a, b, c;

    // Set up the internal state
    a = b = c = 0xdeadbeef + (static_cast<uint32_t>(length) << 2) + hash1;
    c += hash2;

    // handle most of the key
    while (length > 3)
    {
        a += k[0];
        b += k[1];
        c += k[2];
        bitMixer(a,b,c);
        length -= 3;
        k += 3;
    }

    // handle the last 3 uint32_t's
    switch (length)  // all case statements fall through
    {
573 574
        case 3 : c += k[2]; [[fallthrough]];
        case 2 : b += k[1]; [[fallthrough]];
575 576
        case 1 : a += k[0];
            bitMixerFinal(a,b,c);
577
            [[fallthrough]];
578 579 580 581 582 583 584 585 586 587 588 589 590 591
        case 0 :  // case 0: nothing left to add
            break;
    }

    // report the result
    hash1 = c;
    hash2 = b;

    // return primary hash value
    return c;
}


// ************************************************************************* //