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Diffstat (limited to 'dbus/dbus-hash.c')
| -rw-r--r-- | dbus/dbus-hash.c | 1083 |
1 files changed, 1083 insertions, 0 deletions
diff --git a/dbus/dbus-hash.c b/dbus/dbus-hash.c index e69de29b..a8a231ef 100644 --- a/dbus/dbus-hash.c +++ b/dbus/dbus-hash.c @@ -0,0 +1,1083 @@ +/* -*- mode: C; c-file-style: "gnu" -*- */ +/* dbus-hash.c Generic hash table utility (internal to D-BUS implementation) + * + * Copyright (C) 2002 Red Hat, Inc. + * Copyright (c) 1991-1993 The Regents of the University of California. + * Copyright (c) 1994 Sun Microsystems, Inc. + * + * Hash table implementation based on generic/tclHash.c from the Tcl + * source code. The original Tcl license applies to portions of the + * code from tclHash.c; the Tcl license follows this standad D-BUS + * license information. + * + * Licensed under the Academic Free License version 1.2 + * + * This program 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 2 of the License, or + * (at your option) any later version. + * + * This program 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 + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ +/* + * The following copyright applies to code from the Tcl distribution. + * + * Copyright (c) 1991-1993 The Regents of the University of California. + * Copyright (c) 1994 Sun Microsystems, Inc. + * + * This software is copyrighted by the Regents of the University of + * California, Sun Microsystems, Inc., Scriptics Corporation, and + * other parties. The following terms apply to all files associated + * with the software unless explicitly disclaimed in individual files. + * + * The authors hereby grant permission to use, copy, modify, + * distribute, and license this software and its documentation for any + * purpose, provided that existing copyright notices are retained in + * all copies and that this notice is included verbatim in any + * distributions. No written agreement, license, or royalty fee is + * required for any of the authorized uses. Modifications to this + * software may be copyrighted by their authors and need not follow + * the licensing terms described here, provided that the new terms are + * clearly indicated on the first page of each file where they apply. + * + * IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY + * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL + * DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, + * OR ANY DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + * + * THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND + * NON-INFRINGEMENT. THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, + * AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE + * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. + * + * GOVERNMENT USE: If you are acquiring this software on behalf of the + * U.S. government, the Government shall have only "Restricted Rights" + * in the software and related documentation as defined in the Federal + * Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2). If you + * are acquiring the software on behalf of the Department of Defense, + * the software shall be classified as "Commercial Computer Software" + * and the Government shall have only "Restricted Rights" as defined + * in Clause 252.227-7013 (c) (1) of DFARs. Notwithstanding the + * foregoing, the authors grant the U.S. Government and others acting + * in its behalf permission to use and distribute the software in + * accordance with the terms specified in this license. + */ + +#include "dbus-memory.h" + +typedef struct DBusHashEntry DBusHashEntry; + + +#if 0 + +/* + * Forward declaration of Tcl_HashTable. Needed by some C++ compilers + * to prevent errors when the forward reference to Tcl_HashTable is + * encountered in the Tcl_HashEntry structure. + */ + +#ifdef __cplusplus +struct Tcl_HashTable; +#endif + +/* + * Structure definition for an entry in a hash table. No-one outside + * Tcl should access any of these fields directly; use the macros + * defined below. + */ + +typedef struct Tcl_HashEntry { + struct Tcl_HashEntry *nextPtr; /* Pointer to next entry in this + * hash bucket, or NULL for end of + * chain. */ + struct Tcl_HashTable *tablePtr; /* Pointer to table containing entry. */ + struct Tcl_HashEntry **bucketPtr; /* Pointer to bucket that points to + * first entry in this entry's chain: + * used for deleting the entry. */ + ClientData clientData; /* Application stores something here + * with Tcl_SetHashValue. */ + union { /* Key has one of these forms: */ + char *oneWordValue; /* One-word value for key. */ + int words[1]; /* Multiple integer words for key. + * The actual size will be as large + * as necessary for this table's + * keys. */ + char string[4]; /* String for key. The actual size + * will be as large as needed to hold + * the key. */ + } key; /* MUST BE LAST FIELD IN RECORD!! */ +} Tcl_HashEntry; + +/* + * Structure definition for a hash table. Must be in tcl.h so clients + * can allocate space for these structures, but clients should never + * access any fields in this structure. + */ + +#define TCL_SMALL_HASH_TABLE 4 +typedef struct Tcl_HashTable { + Tcl_HashEntry **buckets; /* Pointer to bucket array. Each + * element points to first entry in + * bucket's hash chain, or NULL. */ + Tcl_HashEntry *staticBuckets[TCL_SMALL_HASH_TABLE]; + /* Bucket array used for small tables + * (to avoid mallocs and frees). */ + int numBuckets; /* Total number of buckets allocated + * at **bucketPtr. */ + int numEntries; /* Total number of entries present + * in table. */ + int rebuildSize; /* Enlarge table when numEntries gets + * to be this large. */ + int downShift; /* Shift count used in hashing + * function. Designed to use high- + * order bits of randomized keys. */ + int mask; /* Mask value used in hashing + * function. */ + int keyType; /* Type of keys used in this table. + * It's either TCL_STRING_KEYS, + * TCL_ONE_WORD_KEYS, or an integer + * giving the number of ints that + * is the size of the key. + */ + Tcl_HashEntry *(*findProc) _ANSI_ARGS_((struct Tcl_HashTable *tablePtr, + CONST char *key)); + Tcl_HashEntry *(*createProc) _ANSI_ARGS_((struct Tcl_HashTable *tablePtr, + CONST char *key, int *newPtr)); +} Tcl_HashTable; + +/* + * Structure definition for information used to keep track of searches + * through hash tables: + */ + +typedef struct Tcl_HashSearch { + Tcl_HashTable *tablePtr; /* Table being searched. */ + int nextIndex; /* Index of next bucket to be + * enumerated after present one. */ + Tcl_HashEntry *nextEntryPtr; /* Next entry to be enumerated in the + * the current bucket. */ +} Tcl_HashSearch; + + +/* + * When there are this many entries per bucket, on average, rebuild + * the hash table to make it larger. + */ + +#define REBUILD_MULTIPLIER 3 + + +/* + * The following macro takes a preliminary integer hash value and + * produces an index into a hash tables bucket list. The idea is + * to make it so that preliminary values that are arbitrarily similar + * will end up in different buckets. The hash function was taken + * from a random-number generator. + */ + +#define RANDOM_INDEX(tablePtr, i) \ + (((((long) (i))*1103515245) >> (tablePtr)->downShift) & (tablePtr)->mask) + +/* + * Procedure prototypes for static procedures in this file: + */ + +static Tcl_HashEntry * ArrayFind (Tcl_HashTable *tablePtr, + CONST char *key); +static Tcl_HashEntry * ArrayCreate (Tcl_HashTable *tablePtr, + CONST char *key, int *newPtr); +static Tcl_HashEntry * BogusFind (Tcl_HashTable *tablePtr, + CONST char *key); +static Tcl_HashEntry * BogusCreate (Tcl_HashTable *tablePtr, + CONST char *key, int *newPtr); +static unsigned int HashString (CONST char *string); +static void RebuildTable (Tcl_HashTable *tablePtr); +static Tcl_HashEntry * StringFind (Tcl_HashTable *tablePtr, + CONST char *key); +static Tcl_HashEntry * StringCreate (Tcl_HashTable *tablePtr, + CONST char *key, int *newPtr); +static Tcl_HashEntry * OneWordFind (Tcl_HashTable *tablePtr, + CONST char *key); +static Tcl_HashEntry * OneWordCreate (Tcl_HashTable *tablePtr, + CONST char *key, int *newPtr); + +/* + *---------------------------------------------------------------------- + * + * Tcl_InitHashTable -- + * + * Given storage for a hash table, set up the fields to prepare + * the hash table for use. + * + * Results: + * None. + * + * Side effects: + * TablePtr is now ready to be passed to Tcl_FindHashEntry and + * Tcl_CreateHashEntry. + * + *---------------------------------------------------------------------- + */ + +void +Tcl_InitHashTable(tablePtr, keyType) + register Tcl_HashTable *tablePtr; /* Pointer to table record, which + * is supplied by the caller. */ + int keyType; /* Type of keys to use in table: + * TCL_STRING_KEYS, TCL_ONE_WORD_KEYS, + * or an integer >= 2. */ +{ +#if (TCL_SMALL_HASH_TABLE != 4) + panic("Tcl_InitHashTable: TCL_SMALL_HASH_TABLE is %d, not 4\n", + TCL_SMALL_HASH_TABLE); +#endif + + tablePtr->buckets = tablePtr->staticBuckets; + tablePtr->staticBuckets[0] = tablePtr->staticBuckets[1] = 0; + tablePtr->staticBuckets[2] = tablePtr->staticBuckets[3] = 0; + tablePtr->numBuckets = TCL_SMALL_HASH_TABLE; + tablePtr->numEntries = 0; + tablePtr->rebuildSize = TCL_SMALL_HASH_TABLE*REBUILD_MULTIPLIER; + tablePtr->downShift = 28; + tablePtr->mask = 3; + tablePtr->keyType = keyType; + if (keyType == TCL_STRING_KEYS) { + tablePtr->findProc = StringFind; + tablePtr->createProc = StringCreate; + } else if (keyType == TCL_ONE_WORD_KEYS) { + tablePtr->findProc = OneWordFind; + tablePtr->createProc = OneWordCreate; + } else { + tablePtr->findProc = ArrayFind; + tablePtr->createProc = ArrayCreate; + }; +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_DeleteHashEntry -- + * + * Remove a single entry from a hash table. + * + * Results: + * None. + * + * Side effects: + * The entry given by entryPtr is deleted from its table and + * should never again be used by the caller. It is up to the + * caller to free the clientData field of the entry, if that + * is relevant. + * + *---------------------------------------------------------------------- + */ + +void +Tcl_DeleteHashEntry(entryPtr) + Tcl_HashEntry *entryPtr; +{ + register Tcl_HashEntry *prevPtr; + + if (*entryPtr->bucketPtr == entryPtr) { + *entryPtr->bucketPtr = entryPtr->nextPtr; + } else { + for (prevPtr = *entryPtr->bucketPtr; ; prevPtr = prevPtr->nextPtr) { + if (prevPtr == NULL) { + panic("malformed bucket chain in Tcl_DeleteHashEntry"); + } + if (prevPtr->nextPtr == entryPtr) { + prevPtr->nextPtr = entryPtr->nextPtr; + break; + } + } + } + entryPtr->tablePtr->numEntries--; + ckfree((char *) entryPtr); +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_DeleteHashTable -- + * + * Free up everything associated with a hash table except for + * the record for the table itself. + * + * Results: + * None. + * + * Side effects: + * The hash table is no longer useable. + * + *---------------------------------------------------------------------- + */ + +void +Tcl_DeleteHashTable(tablePtr) + register Tcl_HashTable *tablePtr; /* Table to delete. */ +{ + register Tcl_HashEntry *hPtr, *nextPtr; + int i; + + /* + * Free up all the entries in the table. + */ + + for (i = 0; i < tablePtr->numBuckets; i++) { + hPtr = tablePtr->buckets[i]; + while (hPtr != NULL) { + nextPtr = hPtr->nextPtr; + ckfree((char *) hPtr); + hPtr = nextPtr; + } + } + + /* + * Free up the bucket array, if it was dynamically allocated. + */ + + if (tablePtr->buckets != tablePtr->staticBuckets) { + ckfree((char *) tablePtr->buckets); + } + + /* + * Arrange for panics if the table is used again without + * re-initialization. + */ + + tablePtr->findProc = BogusFind; + tablePtr->createProc = BogusCreate; +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_FirstHashEntry -- + * + * Locate the first entry in a hash table and set up a record + * that can be used to step through all the remaining entries + * of the table. + * + * Results: + * The return value is a pointer to the first entry in tablePtr, + * or NULL if tablePtr has no entries in it. The memory at + * *searchPtr is initialized so that subsequent calls to + * Tcl_NextHashEntry will return all of the entries in the table, + * one at a time. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +Tcl_HashEntry * +Tcl_FirstHashEntry(tablePtr, searchPtr) + Tcl_HashTable *tablePtr; /* Table to search. */ + Tcl_HashSearch *searchPtr; /* Place to store information about + * progress through the table. */ +{ + searchPtr->tablePtr = tablePtr; + searchPtr->nextIndex = 0; + searchPtr->nextEntryPtr = NULL; + return Tcl_NextHashEntry(searchPtr); +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_NextHashEntry -- + * + * Once a hash table enumeration has been initiated by calling + * Tcl_FirstHashEntry, this procedure may be called to return + * successive elements of the table. + * + * Results: + * The return value is the next entry in the hash table being + * enumerated, or NULL if the end of the table is reached. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +Tcl_HashEntry * +Tcl_NextHashEntry(searchPtr) + register Tcl_HashSearch *searchPtr; /* Place to store information about + * progress through the table. Must + * have been initialized by calling + * Tcl_FirstHashEntry. */ +{ + Tcl_HashEntry *hPtr; + + while (searchPtr->nextEntryPtr == NULL) { + if (searchPtr->nextIndex >= searchPtr->tablePtr->numBuckets) { + return NULL; + } + searchPtr->nextEntryPtr = + searchPtr->tablePtr->buckets[searchPtr->nextIndex]; + searchPtr->nextIndex++; + } + hPtr = searchPtr->nextEntryPtr; + searchPtr->nextEntryPtr = hPtr->nextPtr; + return hPtr; +} + +/* + *---------------------------------------------------------------------- + * + * Tcl_HashStats -- + * + * Return statistics describing the layout of the hash table + * in its hash buckets. + * + * Results: + * The return value is a malloc-ed string containing information + * about tablePtr. It is the caller's responsibility to free + * this string. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +char * +Tcl_HashStats(tablePtr) + Tcl_HashTable *tablePtr; /* Table for which to produce stats. */ +{ +#define NUM_COUNTERS 10 + int count[NUM_COUNTERS], overflow, i, j; + double average, tmp; + register Tcl_HashEntry *hPtr; + char *result, *p; + + /* + * Compute a histogram of bucket usage. + */ + + for (i = 0; i < NUM_COUNTERS; i++) { + count[i] = 0; + } + overflow = 0; + average = 0.0; + for (i = 0; i < tablePtr->numBuckets; i++) { + j = 0; + for (hPtr = tablePtr->buckets[i]; hPtr != NULL; hPtr = hPtr->nextPtr) { + j++; + } + if (j < NUM_COUNTERS) { + count[j]++; + } else { + overflow++; + } + tmp = j; + average += (tmp+1.0)*(tmp/tablePtr->numEntries)/2.0; + } + + /* + * Print out the histogram and a few other pieces of information. + */ + + result = (char *) ckalloc((unsigned) ((NUM_COUNTERS*60) + 300)); + sprintf(result, "%d entries in table, %d buckets\n", + tablePtr->numEntries, tablePtr->numBuckets); + p = result + strlen(result); + for (i = 0; i < NUM_COUNTERS; i++) { + sprintf(p, "number of buckets with %d entries: %d\n", + i, count[i]); + p += strlen(p); + } + sprintf(p, "number of buckets with %d or more entries: %d\n", + NUM_COUNTERS, overflow); + p += strlen(p); + sprintf(p, "average search distance for entry: %.1f", average); + return result; +} + +/* + *---------------------------------------------------------------------- + * + * HashString -- + * + * Compute a one-word summary of a text string, which can be + * used to generate a hash index. + * + * Results: + * The return value is a one-word summary of the information in + * string. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +static unsigned int +HashString(string) + register CONST char *string;/* String from which to compute hash value. */ +{ + register unsigned int result; + register int c; + + /* + * I tried a zillion different hash functions and asked many other + * people for advice. Many people had their own favorite functions, + * all different, but no-one had much idea why they were good ones. + * I chose the one below (multiply by 9 and add new character) + * because of the following reasons: + * + * 1. Multiplying by 10 is perfect for keys that are decimal strings, + * and multiplying by 9 is just about as good. + * 2. Times-9 is (shift-left-3) plus (old). This means that each + * character's bits hang around in the low-order bits of the + * hash value for ever, plus they spread fairly rapidly up to + * the high-order bits to fill out the hash value. This seems + * works well both for decimal and non-decimal strings. + */ + + result = 0; + while (1) { + c = *string; + string++; + if (c == 0) { + break; + } + result += (result<<3) + c; + } + return result; +} + +/* + *---------------------------------------------------------------------- + * + * StringFind -- + * + * Given a hash table with string keys, and a string key, find + * the entry with a matching key. + * + * Results: + * The return value is a token for the matching entry in the + * hash table, or NULL if there was no matching entry. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +StringFind(tablePtr, key) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + CONST char *key; /* Key to use to find matching entry. */ +{ + register Tcl_HashEntry *hPtr; + register CONST char *p1, *p2; + int index; + + index = HashString(key) & tablePtr->mask; + + /* + * Search all of the entries in the appropriate bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + for (p1 = key, p2 = hPtr->key.string; ; p1++, p2++) { + if (*p1 != *p2) { + break; + } + if (*p1 == '\0') { + return hPtr; + } + } + } + return NULL; +} + +/* + *---------------------------------------------------------------------- + * + * StringCreate -- + * + * Given a hash table with string keys, and a string key, find + * the entry with a matching key. If there is no matching entry, + * then create a new entry that does match. + * + * Results: + * The return value is a pointer to the matching entry. If this + * is a newly-created entry, then *newPtr will be set to a non-zero + * value; otherwise *newPtr will be set to 0. If this is a new + * entry the value stored in the entry will initially be 0. + * + * Side effects: + * A new entry may be added to the hash table. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +StringCreate(tablePtr, key, newPtr) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + CONST char *key; /* Key to use to find or create matching + * entry. */ + int *newPtr; /* Store info here telling whether a new + * entry was created. */ +{ + register Tcl_HashEntry *hPtr; + register CONST char *p1, *p2; + int index; + + index = HashString(key) & tablePtr->mask; + + /* + * Search all of the entries in this bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + for (p1 = key, p2 = hPtr->key.string; ; p1++, p2++) { + if (*p1 != *p2) { + break; + } + if (*p1 == '\0') { + *newPtr = 0; + return hPtr; + } + } + } + + /* + * Entry not found. Add a new one to the bucket. + */ + + *newPtr = 1; + hPtr = (Tcl_HashEntry *) ckalloc((unsigned) + (sizeof(Tcl_HashEntry) + strlen(key) - (sizeof(hPtr->key) -1))); + hPtr->tablePtr = tablePtr; + hPtr->bucketPtr = &(tablePtr->buckets[index]); + hPtr->nextPtr = *hPtr->bucketPtr; + hPtr->clientData = 0; + strcpy(hPtr->key.string, key); + *hPtr->bucketPtr = hPtr; + tablePtr->numEntries++; + + /* + * If the table has exceeded a decent size, rebuild it with many + * more buckets. + */ + + if (tablePtr->numEntries >= tablePtr->rebuildSize) { + RebuildTable(tablePtr); + } + return hPtr; +} + +/* + *---------------------------------------------------------------------- + * + * OneWordFind -- + * + * Given a hash table with one-word keys, and a one-word key, find + * the entry with a matching key. + * + * Results: + * The return value is a token for the matching entry in the + * hash table, or NULL if there was no matching entry. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +OneWordFind(tablePtr, key) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + register CONST char *key; /* Key to use to find matching entry. */ +{ + register Tcl_HashEntry *hPtr; + int index; + + index = RANDOM_INDEX(tablePtr, key); + + /* + * Search all of the entries in the appropriate bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + if (hPtr->key.oneWordValue == key) { + return hPtr; + } + } + return NULL; +} + +/* + *---------------------------------------------------------------------- + * + * OneWordCreate -- + * + * Given a hash table with one-word keys, and a one-word key, find + * the entry with a matching key. If there is no matching entry, + * then create a new entry that does match. + * + * Results: + * The return value is a pointer to the matching entry. If this + * is a newly-created entry, then *newPtr will be set to a non-zero + * value; otherwise *newPtr will be set to 0. If this is a new + * entry the value stored in the entry will initially be 0. + * + * Side effects: + * A new entry may be added to the hash table. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +OneWordCreate(tablePtr, key, newPtr) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + register CONST char *key; /* Key to use to find or create matching + * entry. */ + int *newPtr; /* Store info here telling whether a new + * entry was created. */ +{ + register Tcl_HashEntry *hPtr; + int index; + + index = RANDOM_INDEX(tablePtr, key); + + /* + * Search all of the entries in this bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + if (hPtr->key.oneWordValue == key) { + *newPtr = 0; + return hPtr; + } + } + + /* + * Entry not found. Add a new one to the bucket. + */ + + *newPtr = 1; + hPtr = (Tcl_HashEntry *) ckalloc(sizeof(Tcl_HashEntry)); + hPtr->tablePtr = tablePtr; + hPtr->bucketPtr = &(tablePtr->buckets[index]); + hPtr->nextPtr = *hPtr->bucketPtr; + hPtr->clientData = 0; + hPtr->key.oneWordValue = (char *) key; /* CONST XXXX */ + *hPtr->bucketPtr = hPtr; + tablePtr->numEntries++; + + /* + * If the table has exceeded a decent size, rebuild it with many + * more buckets. + */ + + if (tablePtr->numEntries >= tablePtr->rebuildSize) { + RebuildTable(tablePtr); + } + return hPtr; +} + +/* + *---------------------------------------------------------------------- + * + * ArrayFind -- + * + * Given a hash table with array-of-int keys, and a key, find + * the entry with a matching key. + * + * Results: + * The return value is a token for the matching entry in the + * hash table, or NULL if there was no matching entry. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +ArrayFind(tablePtr, key) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + CONST char *key; /* Key to use to find matching entry. */ +{ + register Tcl_HashEntry *hPtr; + int *arrayPtr = (int *) key; + register int *iPtr1, *iPtr2; + int index, count; + + for (index = 0, count = tablePtr->keyType, iPtr1 = arrayPtr; + count > 0; count--, iPtr1++) { + index += *iPtr1; + } + index = RANDOM_INDEX(tablePtr, index); + + /* + * Search all of the entries in the appropriate bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + for (iPtr1 = arrayPtr, iPtr2 = hPtr->key.words, + count = tablePtr->keyType; ; count--, iPtr1++, iPtr2++) { + if (count == 0) { + return hPtr; + } + if (*iPtr1 != *iPtr2) { + break; + } + } + } + return NULL; +} + +/* + *---------------------------------------------------------------------- + * + * ArrayCreate -- + * + * Given a hash table with one-word keys, and a one-word key, find + * the entry with a matching key. If there is no matching entry, + * then create a new entry that does match. + * + * Results: + * The return value is a pointer to the matching entry. If this + * is a newly-created entry, then *newPtr will be set to a non-zero + * value; otherwise *newPtr will be set to 0. If this is a new + * entry the value stored in the entry will initially be 0. + * + * Side effects: + * A new entry may be added to the hash table. + * + *---------------------------------------------------------------------- + */ + +static Tcl_HashEntry * +ArrayCreate(tablePtr, key, newPtr) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + register CONST char *key; /* Key to use to find or create matching + * entry. */ + int *newPtr; /* Store info here telling whether a new + * entry was created. */ +{ + register Tcl_HashEntry *hPtr; + int *arrayPtr = (int *) key; + register int *iPtr1, *iPtr2; + int index, count; + + for (index = 0, count = tablePtr->keyType, iPtr1 = arrayPtr; + count > 0; count--, iPtr1++) { + index += *iPtr1; + } + index = RANDOM_INDEX(tablePtr, index); + + /* + * Search all of the entries in the appropriate bucket. + */ + + for (hPtr = tablePtr->buckets[index]; hPtr != NULL; + hPtr = hPtr->nextPtr) { + for (iPtr1 = arrayPtr, iPtr2 = hPtr->key.words, + count = tablePtr->keyType; ; count--, iPtr1++, iPtr2++) { + if (count == 0) { + *newPtr = 0; + return hPtr; + } + if (*iPtr1 != *iPtr2) { + break; + } + } + } + + /* + * Entry not found. Add a new one to the bucket. + */ + + *newPtr = 1; + hPtr = (Tcl_HashEntry *) ckalloc((unsigned) (sizeof(Tcl_HashEntry) + + (tablePtr->keyType*sizeof(int)) - 4)); + hPtr->tablePtr = tablePtr; + hPtr->bucketPtr = &(tablePtr->buckets[index]); + hPtr->nextPtr = *hPtr->bucketPtr; + hPtr->clientData = 0; + for (iPtr1 = arrayPtr, iPtr2 = hPtr->key.words, count = tablePtr->keyType; + count > 0; count--, iPtr1++, iPtr2++) { + *iPtr2 = *iPtr1; + } + *hPtr->bucketPtr = hPtr; + tablePtr->numEntries++; + + /* + * If the table has exceeded a decent size, rebuild it with many + * more buckets. + */ + + if (tablePtr->numEntries >= tablePtr->rebuildSize) { + RebuildTable(tablePtr); + } + return hPtr; +} + +/* + *---------------------------------------------------------------------- + * + * BogusFind -- + * + * This procedure is invoked when an Tcl_FindHashEntry is called + * on a table that has been deleted. + * + * Results: + * If panic returns (which it shouldn't) this procedure returns + * NULL. + * + * Side effects: + * Generates a panic. + * + *---------------------------------------------------------------------- + */ + +/* ARGSUSED */ +static Tcl_HashEntry * +BogusFind(tablePtr, key) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + CONST char *key; /* Key to use to find matching entry. */ +{ + panic("called Tcl_FindHashEntry on deleted table"); + return NULL; +} + +/* + *---------------------------------------------------------------------- + * + * BogusCreate -- + * + * This procedure is invoked when an Tcl_CreateHashEntry is called + * on a table that has been deleted. + * + * Results: + * If panic returns (which it shouldn't) this procedure returns + * NULL. + * + * Side effects: + * Generates a panic. + * + *---------------------------------------------------------------------- + */ + +/* ARGSUSED */ +static Tcl_HashEntry * +BogusCreate(tablePtr, key, newPtr) + Tcl_HashTable *tablePtr; /* Table in which to lookup entry. */ + CONST char *key; /* Key to use to find or create matching + * entry. */ + int *newPtr; /* Store info here telling whether a new + * entry was created. */ +{ + panic("called Tcl_CreateHashEntry on deleted table"); + return NULL; +} + +/* + *---------------------------------------------------------------------- + * + * RebuildTable -- + * + * This procedure is invoked when the ratio of entries to hash + * buckets becomes too large. It creates a new table with a + * larger bucket array and moves all of the entries into the + * new table. + * + * Results: + * None. + * + * Side effects: + * Memory gets reallocated and entries get re-hashed to new + * buckets. + * + *---------------------------------------------------------------------- + */ + +static void +RebuildTable(tablePtr) + register Tcl_HashTable *tablePtr; /* Table to enlarge. */ +{ + int oldSize, count, index; + Tcl_HashEntry **oldBuckets; + register Tcl_HashEntry **oldChainPtr, **newChainPtr; + register Tcl_HashEntry *hPtr; + + oldSize = tablePtr->numBuckets; + oldBuckets = tablePtr->buckets; + + /* + * Allocate and initialize the new bucket array, and set up + * hashing constants for new array size. + */ + + tablePtr->numBuckets *= 4; + tablePtr->buckets = (Tcl_HashEntry **) ckalloc((unsigned) + (tablePtr->numBuckets * sizeof(Tcl_HashEntry *))); + for (count = tablePtr->numBuckets, newChainPtr = tablePtr->buckets; + count > 0; count--, newChainPtr++) { + *newChainPtr = NULL; + } + tablePtr->rebuildSize *= 4; + tablePtr->downShift -= 2; + tablePtr->mask = (tablePtr->mask << 2) + 3; + + /* + * Rehash all of the existing entries into the new bucket array. + */ + + for (oldChainPtr = oldBuckets; oldSize > 0; oldSize--, oldChainPtr++) { + for (hPtr = *oldChainPtr; hPtr != NULL; hPtr = *oldChainPtr) { + *oldChainPtr = hPtr->nextPtr; + if (tablePtr->keyType == TCL_STRING_KEYS) { + index = HashString(hPtr->key.string) & tablePtr->mask; + } else if (tablePtr->keyType == TCL_ONE_WORD_KEYS) { + index = RANDOM_INDEX(tablePtr, hPtr->key.oneWordValue); + } else { + register int *iPtr; + int count; + + for (index = 0, count = tablePtr->keyType, + iPtr = hPtr->key.words; count > 0; count--, iPtr++) { + index += *iPtr; + } + index = RANDOM_INDEX(tablePtr, index); + } + hPtr->bucketPtr = &(tablePtr->buckets[index]); + hPtr->nextPtr = *hPtr->bucketPtr; + *hPtr->bucketPtr = hPtr; + } + } + + /* + * Free up the old bucket array, if it was dynamically allocated. + */ + + if (oldBuckets != tablePtr->staticBuckets) { + ckfree((char *) oldBuckets); + } +} + +#endif |