diff options
Diffstat (limited to 'src/backend/utils/hash/hashfn.c')
| -rw-r--r-- | src/backend/utils/hash/hashfn.c | 212 |
1 files changed, 112 insertions, 100 deletions
diff --git a/src/backend/utils/hash/hashfn.c b/src/backend/utils/hash/hashfn.c index 3b2f0ec19a..f7b8f3fde6 100644 --- a/src/backend/utils/hash/hashfn.c +++ b/src/backend/utils/hash/hashfn.c @@ -1,13 +1,13 @@ /*------------------------------------------------------------------------- * * hashfn.c-- - * + * * * Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/hash/hashfn.c,v 1.3 1997/08/19 21:35:33 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/hash/hashfn.c,v 1.4 1997/09/07 04:53:38 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -24,96 +24,97 @@ long string_hash(char *key, int keysize) { - int h; - register unsigned char *k = (unsigned char *) key; - - h = 0; - /* - * Convert string to integer - */ - while (*k) - h = h * PRIME1 ^ (*k++ - ' '); - h %= PRIME2; - - return (h); + int h; + register unsigned char *k = (unsigned char *) key; + + h = 0; + + /* + * Convert string to integer + */ + while (*k) + h = h * PRIME1 ^ (*k++ - ' '); + h %= PRIME2; + + return (h); } long tag_hash(int *key, int keysize) { - register long h = 0; - - /* - * Convert tag to integer; Use four byte chunks in a "jump table" - * to go a little faster. Currently the maximum keysize is 16 - * (mar 17 1992) I have put in cases for up to 24. Bigger than - * this will resort to the old behavior of the for loop. (see the - * default case). - */ - switch (keysize) + register long h = 0; + + /* + * Convert tag to integer; Use four byte chunks in a "jump table" to + * go a little faster. Currently the maximum keysize is 16 (mar 17 + * 1992) I have put in cases for up to 24. Bigger than this will + * resort to the old behavior of the for loop. (see the default case). + */ + switch (keysize) { - case 6*sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - /* fall through */ - - case 5*sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - /* fall through */ - - case 4*sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - /* fall through */ - - case 3*sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - /* fall through */ - - case 2*sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - /* fall through */ - + case 6 * sizeof(int): + h = h * PRIME1 ^ (*key); + key++; + /* fall through */ + + case 5 * sizeof(int): + h = h * PRIME1 ^ (*key); + key++; + /* fall through */ + + case 4 * sizeof(int): + h = h * PRIME1 ^ (*key); + key++; + /* fall through */ + + case 3 * sizeof(int): + h = h * PRIME1 ^ (*key); + key++; + /* fall through */ + + case 2 * sizeof(int): + h = h * PRIME1 ^ (*key); + key++; + /* fall through */ + case sizeof(int): - h = h * PRIME1 ^ (*key); - key++; - break; - - default: - for(; keysize > (sizeof(int)-1); keysize -= sizeof(int), key++) h = h * PRIME1 ^ (*key); - /* - * now let's grab the last few bytes of the tag if the tag - * has (size % 4) != 0 (which it sometimes will on a sun3). - */ - if (keysize) + key++; + break; + + default: + for (; keysize > (sizeof(int) - 1); keysize -= sizeof(int), key++) + h = h * PRIME1 ^ (*key); + + /* + * now let's grab the last few bytes of the tag if the tag has + * (size % 4) != 0 (which it sometimes will on a sun3). + */ + if (keysize) { - char *keytmp = (char *)key; - - switch (keysize) + char *keytmp = (char *) key; + + switch (keysize) { case 3: - h = h * PRIME1 ^ (*keytmp); - keytmp++; - /* fall through */ + h = h * PRIME1 ^ (*keytmp); + keytmp++; + /* fall through */ case 2: - h = h * PRIME1 ^ (*keytmp); - keytmp++; - /* fall through */ + h = h * PRIME1 ^ (*keytmp); + keytmp++; + /* fall through */ case 1: - h = h * PRIME1 ^ (*keytmp); - break; + h = h * PRIME1 ^ (*keytmp); + break; } } - break; + break; } - - h %= PRIME2; - return (h); + + h %= PRIME2; + return (h); } /* @@ -129,31 +130,42 @@ tag_hash(int *key, int keysize) long disk_hash(char *key) { - register int n = 0; - register char *str = key; - register int len = strlen(key); - register int loop; - -#define HASHC n = *str++ + 65599 * n - - if (len > 0) { - loop = (len + 8 - 1) >> 3; - - switch(len & (8 - 1)) { - case 0: do { /* All fall throughs */ - HASHC; - case 7: HASHC; - case 6: HASHC; - case 5: HASHC; - case 4: HASHC; - case 3: HASHC; - case 2: HASHC; - case 1: HASHC; - } while (--loop); + register int n = 0; + register char *str = key; + register int len = strlen(key); + register int loop; + +#define HASHC n = *str++ + 65599 * n + + if (len > 0) + { + loop = (len + 8 - 1) >> 3; + + switch (len & (8 - 1)) + { + case 0: + do + { /* All fall throughs */ + HASHC; + case 7: + HASHC; + case 6: + HASHC; + case 5: + HASHC; + case 4: + HASHC; + case 3: + HASHC; + case 2: + HASHC; + case 1: + HASHC; + } while (--loop); + } + } - - } - return(n); + return (n); } -#endif +#endif |