/* Resize only when table after removal of unused elements is either
too full or too empty. */
if ((htab->n_elements - htab->n_deleted) * 2 > htab->size
- || (htab->n_elements - htab->n_deleted) * 8 < htab->size
- && htab->size > 32)
+ || ((htab->n_elements - htab->n_deleted) * 8 < htab->size
+ && htab->size > 32))
nsize = higher_prime_number ((htab->n_elements - htab->n_deleted) * 2);
else
nsize = htab->size;
argument. */
void
-htab_traverse (htab, callback, info)
+htab_traverse_noresize (htab, callback, info)
htab_t htab;
htab_trav callback;
PTR info;
PTR *slot;
PTR *limit;
- if ((htab->n_elements - htab->n_deleted) * 8 < htab->size)
- htab_expand (htab);
-
slot = htab->entries;
limit = slot + htab->size;
while (++slot < limit);
}
+/* Like htab_traverse_noresize, but does resize the table when it is
+ too empty to improve effectivity of subsequent calls. */
+
+void
+htab_traverse (htab, callback, info)
+ htab_t htab;
+ htab_trav callback;
+ PTR info;
+{
+ if ((htab->n_elements - htab->n_deleted) * 8 < htab->size)
+ htab_expand (htab);
+
+ htab_traverse_noresize (htab, callback, info);
+}
+
/* Return the current size of given hash table. */
size_t
return r;
}
+
+/* DERIVED FROM:
+--------------------------------------------------------------------
+lookup2.c, by Bob Jenkins, December 1996, Public Domain.
+hash(), hash2(), hash3, and mix() 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 has no warranty.
+--------------------------------------------------------------------
+*/
+
+/*
+--------------------------------------------------------------------
+mix -- mix 3 32-bit values reversibly.
+For every delta with one or two bit set, and the deltas of all three
+ high bits or all three low bits, whether the original value of a,b,c
+ is almost all zero or is uniformly distributed,
+* If mix() is run forward or backward, at least 32 bits in a,b,c
+ have at least 1/4 probability of changing.
+* If mix() is run forward, every bit of c will change between 1/3 and
+ 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
+mix() was built out of 36 single-cycle latency instructions in a
+ structure that could supported 2x parallelism, like so:
+ a -= b;
+ a -= c; x = (c>>13);
+ b -= c; a ^= x;
+ b -= a; x = (a<<8);
+ c -= a; b ^= x;
+ c -= b; x = (b>>13);
+ ...
+ Unfortunately, superscalar Pentiums and Sparcs can't take advantage
+ of that parallelism. They've also turned some of those single-cycle
+ latency instructions into multi-cycle latency instructions. Still,
+ this is the fastest good hash I could find. There were about 2^^68
+ to choose from. I only looked at a billion or so.
+--------------------------------------------------------------------
+*/
+/* same, but slower, works on systems that might have 8 byte hashval_t's */
+#define mix(a,b,c) \
+{ \
+ a -= b; a -= c; a ^= (c>>13); \
+ b -= c; b -= a; b ^= (a<< 8); \
+ c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \
+ a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \
+ b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \
+ c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \
+ a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \
+ b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \
+ c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \
+}
+
+/*
+--------------------------------------------------------------------
+hash() -- hash a variable-length key into a 32-bit value
+ k : the key (the unaligned variable-length array of bytes)
+ len : the length of the key, counting by bytes
+ level : can be any 4-byte value
+Returns a 32-bit value. Every bit of the key affects every bit of
+the return value. Every 1-bit and 2-bit delta achieves avalanche.
+About 36+6len instructions.
+
+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 (ub1 **)k, do it like this:
+ for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
+
+By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
+code any way you wish, private, educational, or commercial. It's free.
+
+See http://burtleburtle.net/bob/hash/evahash.html
+Use for hash table lookup, or anything where one collision in 2^32 is
+acceptable. Do NOT use for cryptographic purposes.
+--------------------------------------------------------------------
+*/
+
+hashval_t iterative_hash (k_in, length, initval)
+ const PTR k_in; /* the key */
+ register size_t length; /* the length of the key */
+ register hashval_t initval; /* the previous hash, or an arbitrary value */
+{
+ register const unsigned char *k = (const unsigned char *)k_in;
+ register hashval_t a,b,c,len;
+
+ /* Set up the internal state */
+ len = length;
+ a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
+ c = initval; /* the previous hash value */
+
+ /*---------------------------------------- handle most of the key */
+#ifndef WORDS_BIGENDIAN
+ /* On a little-endian machine, if the data is 4-byte aligned we can hash
+ by word for better speed. This gives nondeterministic results on
+ big-endian machines. */
+ if (sizeof (hashval_t) == 4 && (((size_t)k)&3) == 0)
+ while (len >= 12) /* aligned */
+ {
+ a += *(hashval_t *)(k+0);
+ b += *(hashval_t *)(k+4);
+ c += *(hashval_t *)(k+8);
+ mix(a,b,c);
+ k += 12; len -= 12;
+ }
+ else /* unaligned */
+#endif
+ while (len >= 12)
+ {
+ a += (k[0] +((hashval_t)k[1]<<8) +((hashval_t)k[2]<<16) +((hashval_t)k[3]<<24));
+ b += (k[4] +((hashval_t)k[5]<<8) +((hashval_t)k[6]<<16) +((hashval_t)k[7]<<24));
+ c += (k[8] +((hashval_t)k[9]<<8) +((hashval_t)k[10]<<16)+((hashval_t)k[11]<<24));
+ mix(a,b,c);
+ k += 12; len -= 12;
+ }
+
+ /*------------------------------------- handle the last 11 bytes */
+ c += length;
+ switch(len) /* all the case statements fall through */
+ {
+ case 11: c+=((hashval_t)k[10]<<24);
+ case 10: c+=((hashval_t)k[9]<<16);
+ case 9 : c+=((hashval_t)k[8]<<8);
+ /* the first byte of c is reserved for the length */
+ case 8 : b+=((hashval_t)k[7]<<24);
+ case 7 : b+=((hashval_t)k[6]<<16);
+ case 6 : b+=((hashval_t)k[5]<<8);
+ case 5 : b+=k[4];
+ case 4 : a+=((hashval_t)k[3]<<24);
+ case 3 : a+=((hashval_t)k[2]<<16);
+ case 2 : a+=((hashval_t)k[1]<<8);
+ case 1 : a+=k[0];
+ /* case 0: nothing left to add */
+ }
+ mix(a,b,c);
+ /*-------------------------------------------- report the result */
+ return c;
+}
projects / binutils-gdb.git / blobdiff