/*************************************************************************** tagmap.h Simple tag->object mapping functions. **************************************************************************** Copyright Aaron Giles All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name 'MAME' nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ***************************************************************************/ #pragma once #ifndef __TAGMAP_H__ #define __TAGMAP_H__ #include "osdcore.h" #include "astring.h" //************************************************************************** // CONSTANTS //************************************************************************** enum tagmap_error { TMERR_NONE, TMERR_DUPLICATE }; //************************************************************************** // TYPE DEFINITIONS //************************************************************************** // generally used for small tables, though the hash size can be increased // as necessary; good primes are: 53, 97, 193, 389, 769, 1543, 3079, 6151, etc template class tagmap_t { private: // disable copying/assignment tagmap_t(const tagmap_t &); tagmap_t &operator=(const tagmap_t &); public: // an entry in the table class entry_t { friend class tagmap_t<_ElementType, _HashSize>; public: // construction/destruction entry_t(const char *tag, UINT32 fullhash, _ElementType object) : m_next(NULL), m_fullhash(fullhash), m_tag(tag), m_object(object) { } // accessors const astring &tag() const { return m_tag; } _ElementType object() const { return m_object; } // setters void set_object(_ElementType object) { m_object = object; } private: // internal helpers entry_t *next() const { return m_next; } UINT32 fullhash() const { return m_fullhash; } // internal state entry_t * m_next; UINT32 m_fullhash; astring m_tag; _ElementType m_object; }; // construction/destruction tagmap_t() { memset(m_table, 0, sizeof(m_table)); } ~tagmap_t() { reset(); } // core hashing function UINT32 hash(const char *string) const { UINT32 result = *string++; for (char c = *string++; c != 0; c = *string++) result = ((result << 5) | (result >> 27)) + c; return result; } // empty the list void reset() { for (UINT32 hashindex = 0; hashindex < ARRAY_LENGTH(m_table); hashindex++) while (m_table[hashindex] != NULL) remove_common(&m_table[hashindex]); } // add/remove tagmap_error add(const char *tag, _ElementType object, bool replace_if_duplicate = false) { return add_common(tag, object, replace_if_duplicate, false); } tagmap_error add_unique_hash(const char *tag, _ElementType object, bool replace_if_duplicate = false) { return add_common(tag, object, replace_if_duplicate, true); } // remove by tag void remove(const char *tag) { UINT32 fullhash = hash(tag); for (entry_t **entryptr = &m_table[fullhash % ARRAY_LENGTH(m_table)]; *entryptr != NULL; entryptr = &(*entryptr)->m_next) if ((*entryptr)->fullhash() == fullhash && (*entryptr)->tag() == tag) return remove_common(entryptr); } // remove by object void remove(_ElementType object) { for (UINT32 hashindex = 0; hashindex < ARRAY_LENGTH(m_table); hashindex++) for (entry_t **entryptr = &m_table[hashindex]; *entryptr != NULL; entryptr = &(*entryptr)->m_next) if ((*entryptr)->object() == object) return remove_common(entryptr); } // find by tag _ElementType find(const char *tag) const { return find(tag, hash(tag)); } // find by tag with precomputed hash _ElementType find(const char *tag, UINT32 fullhash) const { for (entry_t *entry = m_table[fullhash % ARRAY_LENGTH(m_table)]; entry != NULL; entry = entry->next()) if (entry->fullhash() == fullhash && entry->tag() == tag) return entry->object(); return _ElementType(NULL); } // find by tag without checking anything but the hash _ElementType find_hash_only(const char *tag) const { UINT32 fullhash = hash(tag); for (entry_t *entry = m_table[fullhash % ARRAY_LENGTH(m_table)]; entry != NULL; entry = entry->next()) if (entry->fullhash() == fullhash) return entry->object(); return NULL; } // return first object in the table entry_t *first() const { return next(NULL); } // return next object in the table entry_t *next(entry_t *after) const { // if there's another item in this hash bucket, just return it if (after != NULL && after->next() != NULL) return after->next(); // otherwise scan forward for the next bucket with an entry UINT32 firstindex = (after != NULL) ? (after->fullhash() % ARRAY_LENGTH(m_table) + 1) : 0; for (UINT32 hashindex = firstindex; hashindex < ARRAY_LENGTH(m_table); hashindex++) if (m_table[hashindex] != NULL) return m_table[hashindex]; // all out return NULL; } private: // internal helpers tagmap_error add_common(const char *tag, _ElementType object, bool replace_if_duplicate, bool unique_hash); // remove an entry given a pointer to its pointer void remove_common(entry_t **entryptr) { entry_t *entry = *entryptr; *entryptr = entry->next(); delete entry; } // internal state entry_t * m_table[_HashSize]; }; //************************************************************************** // IMPLEMENTATION //************************************************************************** //------------------------------------------------- // add_common - core implementation of a tagmap // addition //------------------------------------------------- template tagmap_error tagmap_t<_ElementType, _HashSize>::add_common(const char *tag, _ElementType object, bool replace_if_duplicate, bool unique_hash) { UINT32 fullhash = hash(tag); UINT32 hashindex = fullhash % ARRAY_LENGTH(m_table); // first make sure we don't have a duplicate for (entry_t *entry = m_table[hashindex]; entry != NULL; entry = entry->next()) if (entry->fullhash() == fullhash) if (unique_hash || entry->tag() == tag) { if (replace_if_duplicate) entry->set_object(object); return TMERR_DUPLICATE; } // now allocate a new entry and add to the head of the list entry_t *entry = new entry_t(tag, fullhash, object); entry->m_next = m_table[hashindex]; m_table[hashindex] = entry; return TMERR_NONE; } #endif /* __TAGMAP_H__ */