auto import from //depot/cupcake/@135843

1 files changed, 186 insertions, 0 deletions

diff --git a/minzip/Hash.h b/minzip/Hash.h
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+++ b/minzip/Hash.h
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+/*
+ * 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 <stdlib.h>
+#include <stdbool.h>
+#include <assert.h>
+
+/* 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*/