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rpmio/lookup3.c

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00001 /* -------------------------------------------------------------------- */
00002 /*
00003  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
00004  * 
00005  * These are functions for producing 32-bit hashes for hash table lookup.
00006  * jlu32w(), jlu32l(), jlu32lpair(), jlu32b(), _JLU3_MIX(), and _JLU3_FINAL() 
00007  * are externally useful functions.  Routines to test the hash are included 
00008  * if SELF_TEST is defined.  You can use this free for any purpose.  It's in
00009  * the public domain.  It has no warranty.
00010  * 
00011  * You probably want to use jlu32l().  jlu32l() and jlu32b()
00012  * hash byte arrays.  jlu32l() is is faster than jlu32b() on
00013  * little-endian machines.  Intel and AMD are little-endian machines.
00014  * On second thought, you probably want jlu32lpair(), which is identical to
00015  * jlu32l() except it returns two 32-bit hashes for the price of one.  
00016  * You could implement jlu32bpair() if you wanted but I haven't bothered here.
00017  * 
00018  * If you want to find a hash of, say, exactly 7 integers, do
00019  *   a = i1;  b = i2;  c = i3;
00020  *   _JLU3_MIX(a,b,c);
00021  *   a += i4; b += i5; c += i6;
00022  *   _JLU3_MIX(a,b,c);
00023  *   a += i7;
00024  *   _JLU3_FINAL(a,b,c);
00025  * then use c as the hash value.  If you have a variable size array of
00026  * 4-byte integers to hash, use jlu32w().  If you have a byte array (like
00027  * a character string), use jlu32l().  If you have several byte arrays, or
00028  * a mix of things, see the comments above jlu32l().  
00029  * 
00030  * Why is this so big?  I read 12 bytes at a time into 3 4-byte integers, 
00031  * then mix those integers.  This is fast (you can do a lot more thorough
00032  * mixing with 12*3 instructions on 3 integers than you can with 3 instructions
00033  * on 1 byte), but shoehorning those bytes into integers efficiently is messy.
00034 */
00035 /* -------------------------------------------------------------------- */
00036 
00037 #include "system.h"
00038 #include "debug.h"
00039 
00040 #if defined(_JLU3_SELFTEST)
00041 # define _JLU3_jlu32w           1
00042 # define _JLU3_jlu32l           1
00043 # define _JLU3_jlu32lpair       1
00044 # define _JLU3_jlu32b           1
00045 #endif
00046 
00047 /*@-redef@*/
00048 /*@unchecked@*/
00049 static const union _dbswap {
00050     const uint32_t ui;
00051     const unsigned char uc[4];
00052 } endian = { .ui = 0x11223344 };
00053 # define HASH_LITTLE_ENDIAN     (endian.uc[0] == (unsigned char) 0x44)
00054 # define HASH_BIG_ENDIAN        (endian.uc[0] == (unsigned char) 0x11)
00055 /*@=redef@*/
00056 
00057 #ifndef ROTL32
00058 # define ROTL32(x, s) (((x) << (s)) | ((x) >> (32 - (s))))
00059 #endif
00060 
00061 /* NOTE: The _size parameter should be in bytes. */
00062 #define _JLU3_INIT(_h, _size)   (0xdeadbeef + ((uint32_t)(_size)) + (_h))
00063 
00064 /* -------------------------------------------------------------------- */
00065 /*
00066  * _JLU3_MIX -- mix 3 32-bit values reversibly.
00067  * 
00068  * This is reversible, so any information in (a,b,c) before _JLU3_MIX() is
00069  * still in (a,b,c) after _JLU3_MIX().
00070  * 
00071  * If four pairs of (a,b,c) inputs are run through _JLU3_MIX(), or through
00072  * _JLU3_MIX() in reverse, there are at least 32 bits of the output that
00073  * are sometimes the same for one pair and different for another pair.
00074  * This was tested for:
00075  * * pairs that differed by one bit, by two bits, in any combination
00076  *   of top bits of (a,b,c), or in any combination of bottom bits of
00077  *   (a,b,c).
00078  * * "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
00079  *   the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
00080  *   is commonly produced by subtraction) look like a single 1-bit
00081  *   difference.
00082  * * the base values were pseudorandom, all zero but one bit set, or 
00083  *   all zero plus a counter that starts at zero.
00084  * 
00085  * Some k values for my "a-=c; a^=ROTL32(c,k); c+=b;" arrangement that
00086  * satisfy this are
00087  *     4  6  8 16 19  4
00088  *     9 15  3 18 27 15
00089  *    14  9  3  7 17  3
00090  * Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
00091  * for "differ" defined as + with a one-bit base and a two-bit delta.  I
00092  * used http://burtleburtle.net/bob/hash/avalanche.html to choose 
00093  * the operations, constants, and arrangements of the variables.
00094  * 
00095  * This does not achieve avalanche.  There are input bits of (a,b,c)
00096  * that fail to affect some output bits of (a,b,c), especially of a.  The
00097  * most thoroughly mixed value is c, but it doesn't really even achieve
00098  * avalanche in c.
00099  * 
00100  * This allows some parallelism.  Read-after-writes are good at doubling
00101  * the number of bits affected, so the goal of mixing pulls in the opposite
00102  * direction as the goal of parallelism.  I did what I could.  Rotates
00103  * seem to cost as much as shifts on every machine I could lay my hands
00104  * on, and rotates are much kinder to the top and bottom bits, so I used
00105  * rotates.
00106  */
00107 /* -------------------------------------------------------------------- */
00108 #define _JLU3_MIX(a,b,c) \
00109 { \
00110   a -= c;  a ^= ROTL32(c, 4);  c += b; \
00111   b -= a;  b ^= ROTL32(a, 6);  a += c; \
00112   c -= b;  c ^= ROTL32(b, 8);  b += a; \
00113   a -= c;  a ^= ROTL32(c,16);  c += b; \
00114   b -= a;  b ^= ROTL32(a,19);  a += c; \
00115   c -= b;  c ^= ROTL32(b, 4);  b += a; \
00116 }
00117 
00118 /* -------------------------------------------------------------------- */
00142 /* -------------------------------------------------------------------- */
00143 #define _JLU3_FINAL(a,b,c) \
00144 { \
00145   c ^= b; c -= ROTL32(b,14); \
00146   a ^= c; a -= ROTL32(c,11); \
00147   b ^= a; b -= ROTL32(a,25); \
00148   c ^= b; c -= ROTL32(b,16); \
00149   a ^= c; a -= ROTL32(c,4);  \
00150   b ^= a; b -= ROTL32(a,14); \
00151   c ^= b; c -= ROTL32(b,24); \
00152 }
00153 
00154 #if defined(_JLU3_jlu32w)
00155 uint32_t jlu32w(uint32_t h, /*@null@*/ const uint32_t *k, size_t size)
00156         /*@*/;
00157 /* -------------------------------------------------------------------- */
00174 /* -------------------------------------------------------------------- */
00175 uint32_t jlu32w(uint32_t h, const uint32_t *k, size_t size)
00176 {
00177     uint32_t a = _JLU3_INIT(h, (size * sizeof(*k)));
00178     uint32_t b = a;
00179     uint32_t c = a;
00180 
00181     if (k == NULL)
00182         goto exit;
00183 
00184     /*----------------------------------------------- handle most of the key */
00185     while (size > 3) {
00186         a += k[0];
00187         b += k[1];
00188         c += k[2];
00189         _JLU3_MIX(a,b,c);
00190         size -= 3;
00191         k += 3;
00192     }
00193 
00194     /*----------------------------------------- handle the last 3 uint32_t's */
00195     switch (size) {
00196     case 3 : c+=k[2];
00197     case 2 : b+=k[1];
00198     case 1 : a+=k[0];
00199         _JLU3_FINAL(a,b,c);
00200         /*@fallthrough@*/
00201     case 0:
00202         break;
00203     }
00204     /*---------------------------------------------------- report the result */
00205 exit:
00206     return c;
00207 }
00208 #endif  /* defined(_JLU3_jlu32w) */
00209 
00210 #if defined(_JLU3_jlu32l)
00211 uint32_t jlu32l(uint32_t h, const void *key, size_t size)
00212         /*@*/;
00213 /* -------------------------------------------------------------------- */
00214 /*
00215  * jlu32l() -- hash a variable-length key into a 32-bit value
00216  *   h       : can be any 4-byte value
00217  *   k       : the key (the unaligned variable-length array of bytes)
00218  *   size    : the size of the key, counting by bytes
00219  * Returns a 32-bit value.  Every bit of the key affects every bit of
00220  * the return value.  Two keys differing by one or two bits will have
00221  * totally different hash values.
00222  * 
00223  * The best hash table sizes are powers of 2.  There is no need to do
00224  * mod a prime (mod is sooo slow!).  If you need less than 32 bits,
00225  * use a bitmask.  For example, if you need only 10 bits, do
00226  *   h = (h & hashmask(10));
00227  * In which case, the hash table should have hashsize(10) elements.
00228  * 
00229  * If you are hashing n strings (uint8_t **)k, do it like this:
00230  *   for (i=0, h=0; i<n; ++i) h = jlu32l(h, k[i], len[i]);
00231  * 
00232  * By Bob Jenkins, 2006.  bob_jenkins@burtleburtle.net.  You may use this
00233  * code any way you wish, private, educational, or commercial.  It's free.
00234  * 
00235  * Use for hash table lookup, or anything where one collision in 2^^32 is
00236  * acceptable.  Do NOT use for cryptographic purposes.
00237  *
00238  * @param h             the previous hash, or an arbitrary value
00239  * @param *k            the key, an array of uint8_t values
00240  * @param size          the size of the key
00241  * @return              the lookup3 hash
00242  */
00243 /* -------------------------------------------------------------------- */
00244 uint32_t jlu32l(uint32_t h, const void *key, size_t size)
00245 {
00246     union { const void *ptr; size_t i; } u;
00247     uint32_t a = _JLU3_INIT(h, size);
00248     uint32_t b = a;
00249     uint32_t c = a;
00250 
00251     if (key == NULL)
00252         goto exit;
00253 
00254     u.ptr = key;
00255     if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
00256         const uint32_t *k = (const uint32_t *)key;      /* read 32-bit chunks */
00257 #ifdef  VALGRIND
00258         const uint8_t  *k8;
00259 #endif
00260 
00261     /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
00262         while (size > 12) {
00263             a += k[0];
00264             b += k[1];
00265             c += k[2];
00266             _JLU3_MIX(a,b,c);
00267             size -= 12;
00268             k += 3;
00269         }
00270 
00271         /*------------------------- handle the last (probably partial) block */
00272         /* 
00273          * "k[2]&0xffffff" actually reads beyond the end of the string, but
00274          * then masks off the part it's not allowed to read.  Because the
00275          * string is aligned, the masked-off tail is in the same word as the
00276          * rest of the string.  Every machine with memory protection I've seen
00277          * does it on word boundaries, so is OK with this.  But VALGRIND will
00278          * still catch it and complain.  The masking trick does make the hash
00279          * noticably faster for short strings (like English words).
00280          */
00281 #ifndef VALGRIND
00282 
00283         switch (size) {
00284         case 12:        c += k[2]; b+=k[1]; a+=k[0]; break;
00285         case 11:        c += k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
00286         case 10:        c += k[2]&0xffff; b+=k[1]; a+=k[0]; break;
00287         case  9:        c += k[2]&0xff; b+=k[1]; a+=k[0]; break;
00288         case  8:        b += k[1]; a+=k[0]; break;
00289         case  7:        b += k[1]&0xffffff; a+=k[0]; break;
00290         case  6:        b += k[1]&0xffff; a+=k[0]; break;
00291         case  5:        b += k[1]&0xff; a+=k[0]; break;
00292         case  4:        a += k[0]; break;
00293         case  3:        a += k[0]&0xffffff; break;
00294         case  2:        a += k[0]&0xffff; break;
00295         case  1:        a += k[0]&0xff; break;
00296         case  0:        goto exit;
00297         }
00298 
00299 #else /* make valgrind happy */
00300 
00301         k8 = (const uint8_t *)k;
00302         switch (size) {
00303         case 12:        c += k[2]; b+=k[1]; a+=k[0]     break;
00304         case 11:        c += ((uint32_t)k8[10])<<16;    /*@fallthrough@*/
00305         case 10:        c += ((uint32_t)k8[9])<<8;      /*@fallthrough@*/
00306         case  9:        c += k8[8];                     /*@fallthrough@*/
00307         case  8:        b += k[1]; a+=k[0];             break;
00308         case  7:        b += ((uint32_t)k8[6])<<16;     /*@fallthrough@*/
00309         case  6:        b += ((uint32_t)k8[5])<<8;      /*@fallthrough@*/
00310         case  5:        b += k8[4];                     /*@fallthrough@*/
00311         case  4:        a += k[0];                      break;
00312         case  3:        a += ((uint32_t)k8[2])<<16;     /*@fallthrough@*/
00313         case  2:        a += ((uint32_t)k8[1])<<8;      /*@fallthrough@*/
00314         case  1:        a += k8[0];                     break;
00315         case  0:        goto exit;
00316         }
00317 
00318 #endif /* !valgrind */
00319 
00320     } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
00321         const uint16_t *k = (const uint16_t *)key;      /* read 16-bit chunks */
00322         const uint8_t  *k8;
00323 
00324         /*----------- all but last block: aligned reads and different mixing */
00325         while (size > 12) {
00326             a += k[0] + (((uint32_t)k[1])<<16);
00327             b += k[2] + (((uint32_t)k[3])<<16);
00328             c += k[4] + (((uint32_t)k[5])<<16);
00329             _JLU3_MIX(a,b,c);
00330             size -= 12;
00331             k += 6;
00332         }
00333 
00334         /*------------------------- handle the last (probably partial) block */
00335         k8 = (const uint8_t *)k;
00336         switch (size) {
00337         case 12:
00338             c += k[4]+(((uint32_t)k[5])<<16);
00339             b += k[2]+(((uint32_t)k[3])<<16);
00340             a += k[0]+(((uint32_t)k[1])<<16);
00341             break;
00342         case 11:
00343             c += ((uint32_t)k8[10])<<16;
00344             /*@fallthrough@*/
00345         case 10:
00346             c += k[4];
00347             b += k[2]+(((uint32_t)k[3])<<16);
00348             a += k[0]+(((uint32_t)k[1])<<16);
00349             break;
00350         case  9:
00351             c += k8[8];
00352             /*@fallthrough@*/
00353         case  8:
00354             b += k[2]+(((uint32_t)k[3])<<16);
00355             a += k[0]+(((uint32_t)k[1])<<16);
00356             break;
00357         case  7:
00358             b += ((uint32_t)k8[6])<<16;
00359             /*@fallthrough@*/
00360         case  6:
00361             b += k[2];
00362             a += k[0]+(((uint32_t)k[1])<<16);
00363             break;
00364         case  5:
00365             b += k8[4];
00366             /*@fallthrough@*/
00367         case  4:
00368             a += k[0]+(((uint32_t)k[1])<<16);
00369             break;
00370         case  3:
00371             a += ((uint32_t)k8[2])<<16;
00372             /*@fallthrough@*/
00373         case  2:
00374             a += k[0];
00375             break;
00376         case  1:
00377             a += k8[0];
00378             break;
00379         case  0:
00380             goto exit;
00381         }
00382 
00383     } else {            /* need to read the key one byte at a time */
00384         const uint8_t *k = (const uint8_t *)key;
00385 
00386         /*----------- all but the last block: affect some 32 bits of (a,b,c) */
00387         while (size > 12) {
00388             a += k[0];
00389             a += ((uint32_t)k[1])<<8;
00390             a += ((uint32_t)k[2])<<16;
00391             a += ((uint32_t)k[3])<<24;
00392             b += k[4];
00393             b += ((uint32_t)k[5])<<8;
00394             b += ((uint32_t)k[6])<<16;
00395             b += ((uint32_t)k[7])<<24;
00396             c += k[8];
00397             c += ((uint32_t)k[9])<<8;
00398             c += ((uint32_t)k[10])<<16;
00399             c += ((uint32_t)k[11])<<24;
00400             _JLU3_MIX(a,b,c);
00401             size -= 12;
00402             k += 12;
00403         }
00404 
00405         /*---------------------------- last block: affect all 32 bits of (c) */
00406         switch (size) {
00407         case 12:        c += ((uint32_t)k[11])<<24;     /*@fallthrough@*/
00408         case 11:        c += ((uint32_t)k[10])<<16;     /*@fallthrough@*/
00409         case 10:        c += ((uint32_t)k[9])<<8;       /*@fallthrough@*/
00410         case  9:        c += k[8];                      /*@fallthrough@*/
00411         case  8:        b += ((uint32_t)k[7])<<24;      /*@fallthrough@*/
00412         case  7:        b += ((uint32_t)k[6])<<16;      /*@fallthrough@*/
00413         case  6:        b += ((uint32_t)k[5])<<8;       /*@fallthrough@*/
00414         case  5:        b += k[4];                      /*@fallthrough@*/
00415         case  4:        a += ((uint32_t)k[3])<<24;      /*@fallthrough@*/
00416         case  3:        a += ((uint32_t)k[2])<<16;      /*@fallthrough@*/
00417         case  2:        a += ((uint32_t)k[1])<<8;       /*@fallthrough@*/
00418         case  1:        a += k[0];
00419             break;
00420         case  0:
00421             goto exit;
00422         }
00423     }
00424 
00425     _JLU3_FINAL(a,b,c);
00426 
00427 exit:
00428     return c;
00429 }
00430 #endif  /* defined(_JLU3_jlu32l) */
00431 
00432 #if defined(_JLU3_jlu32lpair)
00433 void jlu32lpair(/*@null@*/ const void *key, size_t size,
00434                 uint32_t *pc, uint32_t *pb)
00435         /*@modifies *pc, *pb@*/;
00452 void jlu32lpair(const void *key, size_t size, uint32_t *pc, uint32_t *pb)
00453 {
00454     union { const void *ptr; size_t i; } u;
00455     uint32_t a = _JLU3_INIT(*pc, size);
00456     uint32_t b = a;
00457     uint32_t c = a;
00458 
00459     if (key == NULL)
00460         goto exit;
00461 
00462     c += *pb;   /* Add the secondary hash. */
00463 
00464     u.ptr = key;
00465     if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
00466         const uint32_t *k = (const uint32_t *)key;      /* read 32-bit chunks */
00467 #ifdef  VALGRIND
00468         const uint8_t  *k8;
00469 #endif
00470 
00471         /*-- all but last block: aligned reads and affect 32 bits of (a,b,c) */
00472         while (size > 12) {
00473             a += k[0];
00474             b += k[1];
00475             c += k[2];
00476             _JLU3_MIX(a,b,c);
00477             size -= 12;
00478             k += 3;
00479         }
00480         /*------------------------- handle the last (probably partial) block */
00481         /* 
00482          * "k[2]&0xffffff" actually reads beyond the end of the string, but
00483          * then masks off the part it's not allowed to read.  Because the
00484          * string is aligned, the masked-off tail is in the same word as the
00485          * rest of the string.  Every machine with memory protection I've seen
00486          * does it on word boundaries, so is OK with this.  But VALGRIND will
00487          * still catch it and complain.  The masking trick does make the hash
00488          * noticably faster for short strings (like English words).
00489          */
00490 #ifndef VALGRIND
00491 
00492         switch (size) {
00493         case 12:        c += k[2]; b+=k[1]; a+=k[0]; break;
00494         case 11:        c += k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
00495         case 10:        c += k[2]&0xffff; b+=k[1]; a+=k[0]; break;
00496         case  9:        c += k[2]&0xff; b+=k[1]; a+=k[0]; break;
00497         case  8:        b += k[1]; a+=k[0]; break;
00498         case  7:        b += k[1]&0xffffff; a+=k[0]; break;
00499         case  6:        b += k[1]&0xffff; a+=k[0]; break;
00500         case  5:        b += k[1]&0xff; a+=k[0]; break;
00501         case  4:        a += k[0]; break;
00502         case  3:        a += k[0]&0xffffff; break;
00503         case  2:        a += k[0]&0xffff; break;
00504         case  1:        a += k[0]&0xff; break;
00505         case  0:        goto exit;
00506         }
00507 
00508 #else /* make valgrind happy */
00509 
00510         k8 = (const uint8_t *)k;
00511         switch (size) {
00512         case 12:        c += k[2]; b+=k[1]; a+=k[0];    break;
00513         case 11:        c += ((uint32_t)k8[10])<<16;    /*@fallthrough@*/
00514         case 10:        c += ((uint32_t)k8[9])<<8;      /*@fallthrough@*/
00515         case  9:        c += k8[8];                     /*@fallthrough@*/
00516         case  8:        b += k[1]; a+=k[0];             break;
00517         case  7:        b += ((uint32_t)k8[6])<<16;     /*@fallthrough@*/
00518         case  6:        b += ((uint32_t)k8[5])<<8;      /*@fallthrough@*/
00519         case  5:        b += k8[4];                     /*@fallthrough@*/
00520         case  4:        a += k[0];                      break;
00521         case  3:        a += ((uint32_t)k8[2])<<16;     /*@fallthrough@*/
00522         case  2:        a += ((uint32_t)k8[1])<<8;      /*@fallthrough@*/
00523         case  1:        a += k8[0];                     break;
00524         case  0:        goto exit;
00525         }
00526 
00527 #endif /* !valgrind */
00528 
00529     } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
00530         const uint16_t *k = (const uint16_t *)key;      /* read 16-bit chunks */
00531         const uint8_t  *k8;
00532 
00533         /*----------- all but last block: aligned reads and different mixing */
00534         while (size > 12) {
00535             a += k[0] + (((uint32_t)k[1])<<16);
00536             b += k[2] + (((uint32_t)k[3])<<16);
00537             c += k[4] + (((uint32_t)k[5])<<16);
00538             _JLU3_MIX(a,b,c);
00539             size -= 12;
00540             k += 6;
00541         }
00542 
00543         /*------------------------- handle the last (probably partial) block */
00544         k8 = (const uint8_t *)k;
00545         switch (size) {
00546         case 12:
00547             c += k[4]+(((uint32_t)k[5])<<16);
00548             b += k[2]+(((uint32_t)k[3])<<16);
00549             a += k[0]+(((uint32_t)k[1])<<16);
00550             break;
00551         case 11:
00552             c += ((uint32_t)k8[10])<<16;
00553             /*@fallthrough@*/
00554         case 10:
00555             c += k[4];
00556             b += k[2]+(((uint32_t)k[3])<<16);
00557             a += k[0]+(((uint32_t)k[1])<<16);
00558             break;
00559         case  9:
00560             c += k8[8];
00561             /*@fallthrough@*/
00562         case  8:
00563             b += k[2]+(((uint32_t)k[3])<<16);
00564             a += k[0]+(((uint32_t)k[1])<<16);
00565             break;
00566         case  7:
00567             b += ((uint32_t)k8[6])<<16;
00568             /*@fallthrough@*/
00569         case  6:
00570             b += k[2];
00571             a += k[0]+(((uint32_t)k[1])<<16);
00572             break;
00573         case  5:
00574             b += k8[4];
00575             /*@fallthrough@*/
00576         case  4:
00577             a += k[0]+(((uint32_t)k[1])<<16);
00578             break;
00579         case  3:
00580             a += ((uint32_t)k8[2])<<16;
00581             /*@fallthrough@*/
00582         case  2:
00583             a += k[0];
00584             break;
00585         case  1:
00586             a += k8[0];
00587             break;
00588         case  0:
00589             goto exit;
00590         }
00591 
00592     } else {            /* need to read the key one byte at a time */
00593         const uint8_t *k = (const uint8_t *)key;
00594 
00595         /*----------- all but the last block: affect some 32 bits of (a,b,c) */
00596         while (size > 12) {
00597             a += k[0];
00598             a += ((uint32_t)k[1])<<8;
00599             a += ((uint32_t)k[2])<<16;
00600             a += ((uint32_t)k[3])<<24;
00601             b += k[4];
00602             b += ((uint32_t)k[5])<<8;
00603             b += ((uint32_t)k[6])<<16;
00604             b += ((uint32_t)k[7])<<24;
00605             c += k[8];
00606             c += ((uint32_t)k[9])<<8;
00607             c += ((uint32_t)k[10])<<16;
00608             c += ((uint32_t)k[11])<<24;
00609             _JLU3_MIX(a,b,c);
00610             size -= 12;
00611             k += 12;
00612         }
00613 
00614         /*---------------------------- last block: affect all 32 bits of (c) */
00615         switch (size) {
00616         case 12:        c += ((uint32_t)k[11])<<24;     /*@fallthrough@*/
00617         case 11:        c += ((uint32_t)k[10])<<16;     /*@fallthrough@*/
00618         case 10:        c += ((uint32_t)k[9])<<8;       /*@fallthrough@*/
00619         case  9:        c += k[8];                      /*@fallthrough@*/
00620         case  8:        b += ((uint32_t)k[7])<<24;      /*@fallthrough@*/
00621         case  7:        b += ((uint32_t)k[6])<<16;      /*@fallthrough@*/
00622         case  6:        b += ((uint32_t)k[5])<<8;       /*@fallthrough@*/
00623         case  5:        b += k[4];                      /*@fallthrough@*/
00624         case  4:        a += ((uint32_t)k[3])<<24;      /*@fallthrough@*/
00625         case  3:        a += ((uint32_t)k[2])<<16;      /*@fallthrough@*/
00626         case  2:        a += ((uint32_t)k[1])<<8;       /*@fallthrough@*/
00627         case  1:        a += k[0];                      /*@fallthrough@*/
00628             break;
00629         case  0:
00630             goto exit;
00631         }
00632     }
00633 
00634     _JLU3_FINAL(a,b,c);
00635 
00636 exit:
00637     *pc = c;
00638     *pb = b;
00639     return;
00640 }
00641 #endif  /* defined(_JLU3_jlu32lpair) */
00642 
00643 #if defined(_JLU3_jlu32b)
00644 uint32_t jlu32b(uint32_t h, /*@null@*/ const void *key, size_t size)
00645         /*@*/;
00646 /*
00647  * jlu32b():
00648  * This is the same as jlu32w() on big-endian machines.  It is different
00649  * from jlu32l() on all machines.  jlu32b() takes advantage of
00650  * big-endian byte ordering. 
00651  *
00652  * @param h             the previous hash, or an arbitrary value
00653  * @param *k            the key, an array of uint8_t values
00654  * @param size          the size of the key
00655  * @return              the lookup3 hash
00656  */
00657 uint32_t jlu32b(uint32_t h, const void *key, size_t size)
00658 {
00659     union { const void *ptr; size_t i; } u;
00660     uint32_t a = _JLU3_INIT(h, size);
00661     uint32_t b = a;
00662     uint32_t c = a;
00663 
00664     if (key == NULL)
00665         return h;
00666 
00667     u.ptr = key;
00668     if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
00669         const uint32_t *k = (const uint32_t *)key;      /* read 32-bit chunks */
00670 #ifdef  VALGRIND
00671         const uint8_t  *k8;
00672 #endif
00673 
00674         /*-- all but last block: aligned reads and affect 32 bits of (a,b,c) */
00675         while (size > 12) {
00676             a += k[0];
00677             b += k[1];
00678             c += k[2];
00679             _JLU3_MIX(a,b,c);
00680             size -= 12;
00681             k += 3;
00682         }
00683 
00684         /*------------------------- handle the last (probably partial) block */
00685         /* 
00686          * "k[2]<<8" actually reads beyond the end of the string, but
00687          * then shifts out the part it's not allowed to read.  Because the
00688          * string is aligned, the illegal read is in the same word as the
00689          * rest of the string.  Every machine with memory protection I've seen
00690          * does it on word boundaries, so is OK with this.  But VALGRIND will
00691          * still catch it and complain.  The masking trick does make the hash
00692          * noticably faster for short strings (like English words).
00693          */
00694 #ifndef VALGRIND
00695 
00696         switch (size) {
00697         case 12:        c += k[2]; b+=k[1]; a+=k[0]; break;
00698         case 11:        c += k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
00699         case 10:        c += k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
00700         case  9:        c += k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
00701         case  8:        b += k[1]; a+=k[0]; break;
00702         case  7:        b += k[1]&0xffffff00; a+=k[0]; break;
00703         case  6:        b += k[1]&0xffff0000; a+=k[0]; break;
00704         case  5:        b += k[1]&0xff000000; a+=k[0]; break;
00705         case  4:        a += k[0]; break;
00706         case  3:        a += k[0]&0xffffff00; break;
00707         case  2:        a += k[0]&0xffff0000; break;
00708         case  1:        a += k[0]&0xff000000; break;
00709         case  0:        goto exit;
00710     }
00711 
00712 #else  /* make valgrind happy */
00713 
00714         k8 = (const uint8_t *)k;
00715         switch (size) { /* all the case statements fall through */
00716         case 12:        c += k[2]; b+=k[1]; a+=k[0];    break;
00717         case 11:        c += ((uint32_t)k8[10])<<8;     /*@fallthrough@*/
00718         case 10:        c += ((uint32_t)k8[9])<<16;     /*@fallthrough@*/
00719         case  9:        c += ((uint32_t)k8[8])<<24;     /*@fallthrough@*/
00720         case  8:        b += k[1]; a+=k[0];             break;
00721         case  7:        b += ((uint32_t)k8[6])<<8;      /*@fallthrough@*/
00722         case  6:        b += ((uint32_t)k8[5])<<16;     /*@fallthrough@*/
00723         case  5:        b += ((uint32_t)k8[4])<<24;     /*@fallthrough@*/
00724         case  4:        a += k[0];                      break;
00725         case  3:        a += ((uint32_t)k8[2])<<8;      /*@fallthrough@*/
00726         case  2:        a += ((uint32_t)k8[1])<<16;     /*@fallthrough@*/
00727         case  1:        a += ((uint32_t)k8[0])<<24;     break;
00728         case  0:        goto exit;
00729     }
00730 
00731 #endif /* !VALGRIND */
00732 
00733     } else {                        /* need to read the key one byte at a time */
00734         const uint8_t *k = (const uint8_t *)key;
00735 
00736         /*----------- all but the last block: affect some 32 bits of (a,b,c) */
00737         while (size > 12) {
00738             a += ((uint32_t)k[0])<<24;
00739             a += ((uint32_t)k[1])<<16;
00740             a += ((uint32_t)k[2])<<8;
00741             a += ((uint32_t)k[3]);
00742             b += ((uint32_t)k[4])<<24;
00743             b += ((uint32_t)k[5])<<16;
00744             b += ((uint32_t)k[6])<<8;
00745             b += ((uint32_t)k[7]);
00746             c += ((uint32_t)k[8])<<24;
00747             c += ((uint32_t)k[9])<<16;
00748             c += ((uint32_t)k[10])<<8;
00749             c += ((uint32_t)k[11]);
00750             _JLU3_MIX(a,b,c);
00751             size -= 12;
00752             k += 12;
00753         }
00754 
00755         /*---------------------------- last block: affect all 32 bits of (c) */
00756         switch (size) { /* all the case statements fall through */
00757         case 12:        c += k[11];                     /*@fallthrough@*/
00758         case 11:        c += ((uint32_t)k[10])<<8;      /*@fallthrough@*/
00759         case 10:        c += ((uint32_t)k[9])<<16;      /*@fallthrough@*/
00760         case  9:        c += ((uint32_t)k[8])<<24;      /*@fallthrough@*/
00761         case  8:        b += k[7];                      /*@fallthrough@*/
00762         case  7:        b += ((uint32_t)k[6])<<8;       /*@fallthrough@*/
00763         case  6:        b += ((uint32_t)k[5])<<16;      /*@fallthrough@*/
00764         case  5:        b += ((uint32_t)k[4])<<24;      /*@fallthrough@*/
00765         case  4:        a += k[3];                      /*@fallthrough@*/
00766         case  3:        a += ((uint32_t)k[2])<<8;       /*@fallthrough@*/
00767         case  2:        a += ((uint32_t)k[1])<<16;      /*@fallthrough@*/
00768         case  1:        a += ((uint32_t)k[0])<<24;      /*@fallthrough@*/
00769             break;
00770         case  0:
00771             goto exit;
00772         }
00773     }
00774 
00775     _JLU3_FINAL(a,b,c);
00776 
00777 exit:
00778     return c;
00779 }
00780 #endif  /* defined(_JLU3_jlu32b) */
00781 
00782 #if defined(_JLU3_SELFTEST)
00783 
00784 /* used for timings */
00785 static void driver1(void)
00786         /*@*/
00787 {
00788     uint8_t buf[256];
00789     uint32_t i;
00790     uint32_t h=0;
00791     time_t a,z;
00792 
00793     time(&a);
00794     for (i=0; i<256; ++i) buf[i] = 'x';
00795     for (i=0; i<1; ++i) {
00796         h = jlu32l(h, &buf[0], sizeof(buf[0]));
00797     }
00798     time(&z);
00799     if (z-a > 0) printf("time %d %.8x\n", (int)(z-a), h);
00800 }
00801 
00802 /* check that every input bit changes every output bit half the time */
00803 #define HASHSTATE 1
00804 #define HASHLEN   1
00805 #define MAXPAIR 60
00806 #define MAXLEN  70
00807 static void driver2(void)
00808         /*@*/
00809 {
00810     uint8_t qa[MAXLEN+1], qb[MAXLEN+2], *a = &qa[0], *b = &qb[1];
00811     uint32_t c[HASHSTATE], d[HASHSTATE], i=0, j=0, k, l, m=0, z;
00812     uint32_t e[HASHSTATE],f[HASHSTATE],g[HASHSTATE],h[HASHSTATE];
00813     uint32_t x[HASHSTATE],y[HASHSTATE];
00814     uint32_t hlen;
00815 
00816     printf("No more than %d trials should ever be needed \n",MAXPAIR/2);
00817     for (hlen=0; hlen < MAXLEN; ++hlen) {
00818         z=0;
00819         for (i=0; i<hlen; ++i) {        /*-------------- for each input byte, */
00820             for (j=0; j<8; ++j) {       /*--------------- for each input bit, */
00821                 for (m=1; m<8; ++m) {   /*--- for serveral possible initvals, */
00822                     for (l=0; l<HASHSTATE; ++l)
00823                         e[l]=f[l]=g[l]=h[l]=x[l]=y[l]=~((uint32_t)0);
00824 
00825                     /* check that every output bit is affected by that input bit */
00826                     for (k=0; k<MAXPAIR; k+=2) { 
00827                         uint32_t finished=1;
00828                         /* keys have one bit different */
00829                         for (l=0; l<hlen+1; ++l) {a[l] = b[l] = (uint8_t)0;}
00830                         /* have a and b be two keys differing in only one bit */
00831                         a[i] ^= (k<<j);
00832                         a[i] ^= (k>>(8-j));
00833                         c[0] = jlu32l(m, a, hlen);
00834                         b[i] ^= ((k+1)<<j);
00835                         b[i] ^= ((k+1)>>(8-j));
00836                         d[0] = jlu32l(m, b, hlen);
00837                         /* check every bit is 1, 0, set, and not set at least once */
00838                         for (l=0; l<HASHSTATE; ++l) {
00839                             e[l] &= (c[l]^d[l]);
00840                             f[l] &= ~(c[l]^d[l]);
00841                             g[l] &= c[l];
00842                             h[l] &= ~c[l];
00843                             x[l] &= d[l];
00844                             y[l] &= ~d[l];
00845                             if (e[l]|f[l]|g[l]|h[l]|x[l]|y[l]) finished=0;
00846                         }
00847                         if (finished) break;
00848                     }
00849                     if (k>z) z=k;
00850                     if (k == MAXPAIR) {
00851                         printf("Some bit didn't change: ");
00852                         printf("%.8x %.8x %.8x %.8x %.8x %.8x  ",
00853                                 e[0],f[0],g[0],h[0],x[0],y[0]);
00854                         printf("i %d j %d m %d len %d\n", i, j, m, hlen);
00855                     }
00856                     if (z == MAXPAIR) goto done;
00857                 }
00858             }
00859         }
00860    done:
00861         if (z < MAXPAIR) {
00862             printf("Mix success  %2d bytes  %2d initvals  ",i,m);
00863             printf("required  %d  trials\n", z/2);
00864         }
00865     }
00866     printf("\n");
00867 }
00868 
00869 /* Check for reading beyond the end of the buffer and alignment problems */
00870 static void driver3(void)
00871         /*@*/
00872 {
00873     uint8_t buf[MAXLEN+20], *b;
00874     uint32_t len;
00875     uint8_t q[] = "This is the time for all good men to come to the aid of their country...";
00876     uint32_t h;
00877     uint8_t qq[] = "xThis is the time for all good men to come to the aid of their country...";
00878     uint32_t i;
00879     uint8_t qqq[] = "xxThis is the time for all good men to come to the aid of their country...";
00880     uint32_t j;
00881     uint8_t qqqq[] = "xxxThis is the time for all good men to come to the aid of their country...";
00882     uint32_t ref,x,y;
00883     uint8_t *p;
00884     uint32_t m = 13;
00885 
00886     printf("Endianness.  These lines should all be the same (for values filled in):\n");
00887     printf("%.8x                            %.8x                            %.8x\n",
00888         jlu32w(m, (const uint32_t *)q, (sizeof(q)-1)/4),
00889         jlu32w(m, (const uint32_t *)q, (sizeof(q)-5)/4),
00890         jlu32w(m, (const uint32_t *)q, (sizeof(q)-9)/4));
00891     p = q;
00892     printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
00893         jlu32l(m, p, sizeof(q)-1), jlu32l(m, p, sizeof(q)-2),
00894         jlu32l(m, p, sizeof(q)-3), jlu32l(m, p, sizeof(q)-4),
00895         jlu32l(m, p, sizeof(q)-5), jlu32l(m, p, sizeof(q)-6),
00896         jlu32l(m, p, sizeof(q)-7), jlu32l(m, p, sizeof(q)-8),
00897         jlu32l(m, p, sizeof(q)-9), jlu32l(m, p, sizeof(q)-10),
00898         jlu32l(m, p, sizeof(q)-11), jlu32l(m, p, sizeof(q)-12));
00899     p = &qq[1];
00900     printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
00901         jlu32l(m, p, sizeof(q)-1), jlu32l(m, p, sizeof(q)-2),
00902         jlu32l(m, p, sizeof(q)-3), jlu32l(m, p, sizeof(q)-4),
00903         jlu32l(m, p, sizeof(q)-5), jlu32l(m, p, sizeof(q)-6),
00904         jlu32l(m, p, sizeof(q)-7), jlu32l(m, p, sizeof(q)-8),
00905         jlu32l(m, p, sizeof(q)-9), jlu32l(m, p, sizeof(q)-10),
00906         jlu32l(m, p, sizeof(q)-11), jlu32l(m, p, sizeof(q)-12));
00907     p = &qqq[2];
00908     printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
00909         jlu32l(m, p, sizeof(q)-1), jlu32l(m, p, sizeof(q)-2),
00910         jlu32l(m, p, sizeof(q)-3), jlu32l(m, p, sizeof(q)-4),
00911         jlu32l(m, p, sizeof(q)-5), jlu32l(m, p, sizeof(q)-6),
00912         jlu32l(m, p, sizeof(q)-7), jlu32l(m, p, sizeof(q)-8),
00913         jlu32l(m, p, sizeof(q)-9), jlu32l(m, p, sizeof(q)-10),
00914         jlu32l(m, p, sizeof(q)-11), jlu32l(m, p, sizeof(q)-12));
00915     p = &qqqq[3];
00916     printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
00917         jlu32l(m, p, sizeof(q)-1), jlu32l(m, p, sizeof(q)-2),
00918         jlu32l(m, p, sizeof(q)-3), jlu32l(m, p, sizeof(q)-4),
00919         jlu32l(m, p, sizeof(q)-5), jlu32l(m, p, sizeof(q)-6),
00920         jlu32l(m, p, sizeof(q)-7), jlu32l(m, p, sizeof(q)-8),
00921         jlu32l(m, p, sizeof(q)-9), jlu32l(m, p, sizeof(q)-10),
00922         jlu32l(m, p, sizeof(q)-11), jlu32l(m, p, sizeof(q)-12));
00923     printf("\n");
00924     for (h=0, b=buf+1; h<8; ++h, ++b) {
00925         for (i=0; i<MAXLEN; ++i) {
00926             len = i;
00927             for (j=0; j<i; ++j)
00928                 *(b+j)=0;
00929 
00930             /* these should all be equal */
00931             m = 1;
00932             ref = jlu32l(m, b, len);
00933             *(b+i)=(uint8_t)~0;
00934             *(b-1)=(uint8_t)~0;
00935             x = jlu32l(m, b, len);
00936             y = jlu32l(m, b, len);
00937             if ((ref != x) || (ref != y)) 
00938                 printf("alignment error: %.8x %.8x %.8x %d %d\n",ref,x,y, h, i);
00939         }
00940     }
00941 }
00942 
00943 /* check for problems with nulls */
00944 static void driver4(void)
00945         /*@*/
00946 {
00947     uint8_t buf[1];
00948     uint32_t h;
00949     uint32_t i;
00950     uint32_t state[HASHSTATE];
00951 
00952     buf[0] = ~0;
00953     for (i=0; i<HASHSTATE; ++i)
00954         state[i] = 1;
00955     printf("These should all be different\n");
00956     h = 0;
00957     for (i=0; i<8; ++i) {
00958         h = jlu32l(h, buf, 0);
00959         printf("%2ld  0-byte strings, hash is  %.8x\n", (long)i, h);
00960     }
00961 }
00962 
00963 
00964 int main(int argc, char ** argv)
00965 {
00966     driver1();  /* test that the key is hashed: used for timings */
00967     driver2();  /* test that whole key is hashed thoroughly */
00968     driver3();  /* test that nothing but the key is hashed */
00969     driver4();  /* test hashing multiple buffers (all buffers are null) */
00970     return 1;
00971 }
00972 
00973 #endif  /* _JLU3_SELFTEST */

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