void
CacheHash::Feed(uint32_t aVal, uint8_t aLen)
{
switch (mPos) {
case 0:
mA += aVal;
mPos ++;
break;
case 1:
mB += aVal;
mPos ++;
break;
case 2:
mPos = 0;
if (aLen == 4) {
mC += aVal;
hashmix(mA, mB, mC);
}
else {
mC += aVal << 8;
}
}
mLength += aLen;
}
/*
--------------------------------------------------------------------
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.
--------------------------------------------------------------------
*/
uint32_t hashword(
const uint32_t *k, /* the key, an array of uint32_t values */
size_t length, /* the length of the key, in uint32_ts */
uint32_t initval) /* the previous hash, or an arbitrary value */
{
uint32_t a,b,c;
/* Set up the internal state */
a = b = c = 0xdeadbeef + (((uint32_t)length)<<2) + initval;
/*------------------------------------------------- handle most of the key */
while (length > 3)
{
a += k[0];
b += k[1];
c += k[2];
hashmix(a,b,c);
length -= 3;
k += 3;
}
/*------------------------------------------- handle the last 3 uint32_t's */
switch(length) /* all the case statements fall through */
{
case 3 : c+=k[2];
case 2 : b+=k[1];
case 1 : a+=k[0];
hashfinal(a,b,c);
case 0: /* case 0: nothing left to add */
break;
}
/*------------------------------------------------------ report the result */
return c;
}
CacheHash::Hash32_t
CacheHash::GetHash()
{
if (!mFinalized)
{
if (mBufPos) {
Feed(mBuf, mBufPos);
}
mC += mLength;
hashmix(mA, mB, mC);
mFinalized = true;
}
return mC;
}
/*
--------------------------------------------------------------------
hashword2() -- same as hashword(), but take two seeds and return two
32-bit values. pc and pb must both be nonnull, 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().
--------------------------------------------------------------------
*/
void hashword2 (
const uint32_t *k, /* the key, an array of uint32_t values */
size_t length, /* the length of the key, in uint32_ts */
uint32_t *pc, /* IN: seed OUT: primary hash value */
uint32_t *pb) /* IN: more seed OUT: secondary hash value */
{
uint32_t a,b,c;
/* Set up the internal state */
a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + *pc;
c += *pb;
/*------------------------------------------------- handle most of the key */
while (length > 3)
{
a += k[0];
b += k[1];
c += k[2];
hashmix(a,b,c);
length -= 3;
k += 3;
}
/*------------------------------------------- handle the last 3 uint32_t's */
switch(length) /* all the case statements fall through */
{
case 3 : c+=k[2];
case 2 : b+=k[1];
case 1 : a+=k[0];
hashfinal(a,b,c);
case 0: /* case 0: nothing left to add */
break;
}
/*------------------------------------------------------ report the result */
*pc=c; *pb=b;
}
/*
* 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.
*/
uint32_t hashbig( const void *key, size_t length, uint32_t initval)
{
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 + ((uint32_t)length) + initval;
u.ptr = key;
if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
/*------ 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];
hashmix(a,b,c);
length -= 12;
k += 3;
}
/*----------------------------- handle the last (probably partial) block */
/*
* "k[2]<<8" actually reads beyond the end of the string, but
* then shifts out the part it's not allowed to read. Because the
* string is aligned, the illegal read is in the same word as the
* rest of the string. Every machine with memory protection I've seen
* does it on word boundaries, so is OK with this. But VALGRIND will
* still catch it and complain. The masking trick does make the hash
* noticably faster for short strings (like English words).
*/
#ifndef VALGRIND
switch(length)
{
case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
case 8 : b+=k[1]; a+=k[0]; break;
case 7 : b+=k[1]&0xffffff00; a+=k[0]; break;
case 6 : b+=k[1]&0xffff0000; a+=k[0]; break;
case 5 : b+=k[1]&0xff000000; a+=k[0]; break;
case 4 : a+=k[0]; break;
case 3 : a+=k[0]&0xffffff00; break;
case 2 : a+=k[0]&0xffff0000; break;
case 1 : a+=k[0]&0xff000000; break;
case 0 : return c; /* zero length strings require no hashmixing */
}
#else /* make valgrind happy */
{
const uint8_t *k8 = (const uint8_t *)k;
switch(length) /* all the case statements fall through */
{
case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
case 11: c+=((uint32_t)k8[10])<<8; /* fall through */
case 10: c+=((uint32_t)k8[9])<<16; /* fall through */
case 9 : c+=((uint32_t)k8[8])<<24; /* fall through */
case 8 : b+=k[1]; a+=k[0]; break;
case 7 : b+=((uint32_t)k8[6])<<8; /* fall through */
case 6 : b+=((uint32_t)k8[5])<<16; /* fall through */
case 5 : b+=((uint32_t)k8[4])<<24; /* fall through */
case 4 : a+=k[0]; break;
case 3 : a+=((uint32_t)k8[2])<<8; /* fall through */
case 2 : a+=((uint32_t)k8[1])<<16; /* fall through */
case 1 : a+=((uint32_t)k8[0])<<24; break;
case 0 : return c;
}
}
#endif /* !VALGRIND */
} else { /* need to read the key one byte at a time */
const uint8_t *k = (const uint8_t *)key;
/*--------------- all but the last block: affect some 32 bits of (a,b,c) */
while (length > 12)
{
a += ((uint32_t)k[0])<<24;
a += ((uint32_t)k[1])<<16;
a += ((uint32_t)k[2])<<8;
a += ((uint32_t)k[3]);
b += ((uint32_t)k[4])<<24;
b += ((uint32_t)k[5])<<16;
b += ((uint32_t)k[6])<<8;
b += ((uint32_t)k[7]);
c += ((uint32_t)k[8])<<24;
c += ((uint32_t)k[9])<<16;
c += ((uint32_t)k[10])<<8;
c += ((uint32_t)k[11]);
hashmix(a,b,c);
length -= 12;
k += 12;
}
/*-------------------------------- last block: affect all 32 bits of (c) */
switch(length) /* all the case statements fall through */
{
case 12: c+=k[11];
case 11: c+=((uint32_t)k[10])<<8;
case 10: c+=((uint32_t)k[9])<<16;
case 9 : c+=((uint32_t)k[8])<<24;
case 8 : b+=k[7];
case 7 : b+=((uint32_t)k[6])<<8;
case 6 : b+=((uint32_t)k[5])<<16;
case 5 : b+=((uint32_t)k[4])<<24;
case 4 : a+=k[3];
case 3 : a+=((uint32_t)k[2])<<8;
case 2 : a+=((uint32_t)k[1])<<16;
case 1 : a+=((uint32_t)k[0])<<24;
break;
case 0 : return c;
}
}
hashfinal(a,b,c);
return c;
}
/*
* hashlittle2: return 2 32-bit hash values
*
* This is identical to hashlittle(), except it returns two 32-bit hash
* values instead of just one. This is good enough for hash table
* lookup with 2^^64 buckets, or if you want a second hash if you're not
* happy with the first, or if you want a probably-unique 64-bit ID for
* the key. *pc is better hashmixed than *pb, so use *pc first. If you want
* a 64-bit value do something like "*pc + (((uint64_t)*pb)<<32)".
*/
void hashlittle2(
const void *key, /* the key to hash */
size_t length, /* length of the key */
uint32_t *pc, /* IN: primary initval, OUT: primary hash */
uint32_t *pb) /* IN: secondary initval, OUT: secondary hash */
{
uint32_t a,b,c; /* internal state */
union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
/* Set up the internal state */
a = b = c = 0xdeadbeef + ((uint32_t)length) + *pc;
c += *pb;
u.ptr = key;
if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
/*------ 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];
hashmix(a,b,c);
length -= 12;
k += 3;
}
/*----------------------------- handle the last (probably partial) block */
/*
* "k[2]&0xffffff" actually reads beyond the end of the string, but
* then masks off the part it's not allowed to read. Because the
* string is aligned, the masked-off tail is in the same word as the
* rest of the string. Every machine with memory protection I've seen
* does it on word boundaries, so is OK with this. But VALGRIND will
* still catch it and complain. The masking trick does make the hash
* noticably faster for short strings (like English words).
*/
#ifndef VALGRIND
switch(length)
{
case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
case 8 : b+=k[1]; a+=k[0]; break;
case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
case 6 : b+=k[1]&0xffff; a+=k[0]; break;
case 5 : b+=k[1]&0xff; a+=k[0]; break;
case 4 : a+=k[0]; break;
case 3 : a+=k[0]&0xffffff; break;
case 2 : a+=k[0]&0xffff; break;
case 1 : a+=k[0]&0xff; break;
case 0 : *pc=c; *pb=b; return; /* zero length strings require no hashmixing */
}
#else /* make valgrind happy */
{
const uint8_t *k8 = (const uint8_t *)k;
switch(length)
{
case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
case 9 : c+=k8[8]; /* fall through */
case 8 : b+=k[1]; a+=k[0]; break;
case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
case 5 : b+=k8[4]; /* fall through */
case 4 : a+=k[0]; break;
case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
case 1 : a+=k8[0]; break;
case 0 : *pc=c; *pb=b; return; /* zero length strings require no hashmixing */
}
}
#endif /* !valgrind */
} else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
const uint8_t *k8;
/*--------------- all but last block: aligned reads and different hashmixing */
while (length > 12)
{
a += k[0] + (((uint32_t)k[1])<<16);
b += k[2] + (((uint32_t)k[3])<<16);
c += k[4] + (((uint32_t)k[5])<<16);
hashmix(a,b,c);
length -= 12;
k += 6;
}
/*----------------------------- handle the last (probably partial) block */
k8 = (const uint8_t *)k;
switch(length)
{
case 12: c+=k[4]+(((uint32_t)k[5])<<16);
b+=k[2]+(((uint32_t)k[3])<<16);
a+=k[0]+(((uint32_t)k[1])<<16);
break;
case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
case 10: c+=k[4];
b+=k[2]+(((uint32_t)k[3])<<16);
a+=k[0]+(((uint32_t)k[1])<<16);
break;
case 9 : c+=k8[8]; /* fall through */
case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
a+=k[0]+(((uint32_t)k[1])<<16);
break;
case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
case 6 : b+=k[2];
a+=k[0]+(((uint32_t)k[1])<<16);
break;
case 5 : b+=k8[4]; /* fall through */
case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
break;
case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
case 2 : a+=k[0];
break;
case 1 : a+=k8[0];
break;
case 0 : *pc=c; *pb=b; return; /* zero length strings require no hashmixing */
}
} else { /* need to read the key one byte at a time */
const uint8_t *k = (const uint8_t *)key;
/*--------------- all but the last block: affect some 32 bits of (a,b,c) */
while (length > 12)
{
a += k[0];
a += ((uint32_t)k[1])<<8;
a += ((uint32_t)k[2])<<16;
a += ((uint32_t)k[3])<<24;
b += k[4];
b += ((uint32_t)k[5])<<8;
b += ((uint32_t)k[6])<<16;
b += ((uint32_t)k[7])<<24;
c += k[8];
c += ((uint32_t)k[9])<<8;
c += ((uint32_t)k[10])<<16;
c += ((uint32_t)k[11])<<24;
hashmix(a,b,c);
length -= 12;
k += 12;
}
/*-------------------------------- last block: affect all 32 bits of (c) */
switch(length) /* all the case statements fall through */
{
case 12: c+=((uint32_t)k[11])<<24;
case 11: c+=((uint32_t)k[10])<<16;
case 10: c+=((uint32_t)k[9])<<8;
case 9 : c+=k[8];
case 8 : b+=((uint32_t)k[7])<<24;
case 7 : b+=((uint32_t)k[6])<<16;
case 6 : b+=((uint32_t)k[5])<<8;
case 5 : b+=k[4];
case 4 : a+=((uint32_t)k[3])<<24;
case 3 : a+=((uint32_t)k[2])<<16;
case 2 : a+=((uint32_t)k[1])<<8;
case 1 : a+=k[0];
break;
case 0 : *pc=c; *pb=b; return; /* zero length strings require no hashmixing */
}
}
hashfinal(a,b,c);
*pc=c; *pb=b;
}
