From c24a8e688a6312764254beac2b2520bb0c5e998d Mon Sep 17 00:00:00 2001 From: The Android Open Source Project Date: Tue, 3 Mar 2009 19:28:42 -0800 Subject: auto import from //depot/cupcake/@135843 --- minzip/Hash.h | 186 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 186 insertions(+) create mode 100644 minzip/Hash.h (limited to 'minzip/Hash.h') diff --git a/minzip/Hash.h b/minzip/Hash.h new file mode 100644 index 0000000..8194537 --- /dev/null +++ b/minzip/Hash.h @@ -0,0 +1,186 @@ +/* + * Copyright 2007 The Android Open Source Project + * + * General purpose hash table, used for finding classes, methods, etc. + * + * When the number of elements reaches 3/4 of the table's capacity, the + * table will be resized. + */ +#ifndef _MINZIP_HASH +#define _MINZIP_HASH + +#include "inline_magic.h" + +#include +#include +#include + +/* compute the hash of an item with a specific type */ +typedef unsigned int (*HashCompute)(const void* item); + +/* + * Compare a hash entry with a "loose" item after their hash values match. + * Returns { <0, 0, >0 } depending on ordering of items (same semantics + * as strcmp()). + */ +typedef int (*HashCompareFunc)(const void* tableItem, const void* looseItem); + +/* + * This function will be used to free entries in the table. This can be + * NULL if no free is required, free(), or a custom function. + */ +typedef void (*HashFreeFunc)(void* ptr); + +/* + * Used by mzHashForeach(). + */ +typedef int (*HashForeachFunc)(void* data, void* arg); + +/* + * One entry in the hash table. "data" values are expected to be (or have + * the same characteristics as) valid pointers. In particular, a NULL + * value for "data" indicates an empty slot, and HASH_TOMBSTONE indicates + * a no-longer-used slot that must be stepped over during probing. + * + * Attempting to add a NULL or tombstone value is an error. + * + * When an entry is released, we will call (HashFreeFunc)(entry->data). + */ +typedef struct HashEntry { + unsigned int hashValue; + void* data; +} HashEntry; + +#define HASH_TOMBSTONE ((void*) 0xcbcacccd) // invalid ptr value + +/* + * Expandable hash table. + * + * This structure should be considered opaque. + */ +typedef struct HashTable { + int tableSize; /* must be power of 2 */ + int numEntries; /* current #of "live" entries */ + int numDeadEntries; /* current #of tombstone entries */ + HashEntry* pEntries; /* array on heap */ + HashFreeFunc freeFunc; +} HashTable; + +/* + * Create and initialize a HashTable structure, using "initialSize" as + * a basis for the initial capacity of the table. (The actual initial + * table size may be adjusted upward.) If you know exactly how many + * elements the table will hold, pass the result from mzHashSize() in.) + * + * Returns "false" if unable to allocate the table. + */ +HashTable* mzHashTableCreate(size_t initialSize, HashFreeFunc freeFunc); + +/* + * Compute the capacity needed for a table to hold "size" elements. Use + * this when you know ahead of time how many elements the table will hold. + * Pass this value into mzHashTableCreate() to ensure that you can add + * all elements without needing to reallocate the table. + */ +size_t mzHashSize(size_t size); + +/* + * Clear out a hash table, freeing the contents of any used entries. + */ +void mzHashTableClear(HashTable* pHashTable); + +/* + * Free a hash table. + */ +void mzHashTableFree(HashTable* pHashTable); + +/* + * Get #of entries in hash table. + */ +INLINE int mzHashTableNumEntries(HashTable* pHashTable) { + return pHashTable->numEntries; +} + +/* + * Get total size of hash table (for memory usage calculations). + */ +INLINE int mzHashTableMemUsage(HashTable* pHashTable) { + return sizeof(HashTable) + pHashTable->tableSize * sizeof(HashEntry); +} + +/* + * Look up an entry in the table, possibly adding it if it's not there. + * + * If "item" is not found, and "doAdd" is false, NULL is returned. + * Otherwise, a pointer to the found or added item is returned. (You can + * tell the difference by seeing if return value == item.) + * + * An "add" operation may cause the entire table to be reallocated. + */ +void* mzHashTableLookup(HashTable* pHashTable, unsigned int itemHash, void* item, + HashCompareFunc cmpFunc, bool doAdd); + +/* + * Remove an item from the hash table, given its "data" pointer. Does not + * invoke the "free" function; just detaches it from the table. + */ +bool mzHashTableRemove(HashTable* pHashTable, unsigned int hash, void* item); + +/* + * Execute "func" on every entry in the hash table. + * + * If "func" returns a nonzero value, terminate early and return the value. + */ +int mzHashForeach(HashTable* pHashTable, HashForeachFunc func, void* arg); + +/* + * An alternative to mzHashForeach(), using an iterator. + * + * Use like this: + * HashIter iter; + * for (mzHashIterBegin(hashTable, &iter); !mzHashIterDone(&iter); + * mzHashIterNext(&iter)) + * { + * MyData* data = (MyData*)mzHashIterData(&iter); + * } + */ +typedef struct HashIter { + void* data; + HashTable* pHashTable; + int idx; +} HashIter; +INLINE void mzHashIterNext(HashIter* pIter) { + int i = pIter->idx +1; + int lim = pIter->pHashTable->tableSize; + for ( ; i < lim; i++) { + void* data = pIter->pHashTable->pEntries[i].data; + if (data != NULL && data != HASH_TOMBSTONE) + break; + } + pIter->idx = i; +} +INLINE void mzHashIterBegin(HashTable* pHashTable, HashIter* pIter) { + pIter->pHashTable = pHashTable; + pIter->idx = -1; + mzHashIterNext(pIter); +} +INLINE bool mzHashIterDone(HashIter* pIter) { + return (pIter->idx >= pIter->pHashTable->tableSize); +} +INLINE void* mzHashIterData(HashIter* pIter) { + assert(pIter->idx >= 0 && pIter->idx < pIter->pHashTable->tableSize); + return pIter->pHashTable->pEntries[pIter->idx].data; +} + + +/* + * Evaluate hash table performance by examining the number of times we + * have to probe for an entry. + * + * The caller should lock the table beforehand. + */ +typedef unsigned int (*HashCalcFunc)(const void* item); +void mzHashTableProbeCount(HashTable* pHashTable, HashCalcFunc calcFunc, + HashCompareFunc cmpFunc); + +#endif /*_MINZIP_HASH*/ -- cgit v1.1