summaryrefslogtreecommitdiffstats
path: root/minzip/Hash.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--minzip/Hash.c379
1 files changed, 0 insertions, 379 deletions
diff --git a/minzip/Hash.c b/minzip/Hash.c
deleted file mode 100644
index 49bcb3161..000000000
--- a/minzip/Hash.c
+++ /dev/null
@@ -1,379 +0,0 @@
-/*
- * Copyright 2006 The Android Open Source Project
- *
- * Hash table. The dominant calls are add and lookup, with removals
- * happening very infrequently. We use probing, and don't worry much
- * about tombstone removal.
- */
-#include <stdlib.h>
-#include <assert.h>
-
-#define LOG_TAG "minzip"
-#include "Log.h"
-#include "Hash.h"
-
-/* table load factor, i.e. how full can it get before we resize */
-//#define LOAD_NUMER 3 // 75%
-//#define LOAD_DENOM 4
-#define LOAD_NUMER 5 // 62.5%
-#define LOAD_DENOM 8
-//#define LOAD_NUMER 1 // 50%
-//#define LOAD_DENOM 2
-
-/*
- * Compute the capacity needed for a table to hold "size" elements.
- */
-size_t mzHashSize(size_t size) {
- return (size * LOAD_DENOM) / LOAD_NUMER +1;
-}
-
-/*
- * Round up to the next highest power of 2.
- *
- * Found on http://graphics.stanford.edu/~seander/bithacks.html.
- */
-unsigned int roundUpPower2(unsigned int val)
-{
- val--;
- val |= val >> 1;
- val |= val >> 2;
- val |= val >> 4;
- val |= val >> 8;
- val |= val >> 16;
- val++;
-
- return val;
-}
-
-/*
- * Create and initialize a hash table.
- */
-HashTable* mzHashTableCreate(size_t initialSize, HashFreeFunc freeFunc)
-{
- HashTable* pHashTable;
-
- assert(initialSize > 0);
-
- pHashTable = (HashTable*) malloc(sizeof(*pHashTable));
- if (pHashTable == NULL)
- return NULL;
-
- pHashTable->tableSize = roundUpPower2(initialSize);
- pHashTable->numEntries = pHashTable->numDeadEntries = 0;
- pHashTable->freeFunc = freeFunc;
- pHashTable->pEntries =
- (HashEntry*) calloc((size_t)pHashTable->tableSize, sizeof(HashTable));
- if (pHashTable->pEntries == NULL) {
- free(pHashTable);
- return NULL;
- }
-
- return pHashTable;
-}
-
-/*
- * Clear out all entries.
- */
-void mzHashTableClear(HashTable* pHashTable)
-{
- HashEntry* pEnt;
- int i;
-
- pEnt = pHashTable->pEntries;
- for (i = 0; i < pHashTable->tableSize; i++, pEnt++) {
- if (pEnt->data == HASH_TOMBSTONE) {
- // nuke entry
- pEnt->data = NULL;
- } else if (pEnt->data != NULL) {
- // call free func then nuke entry
- if (pHashTable->freeFunc != NULL)
- (*pHashTable->freeFunc)(pEnt->data);
- pEnt->data = NULL;
- }
- }
-
- pHashTable->numEntries = 0;
- pHashTable->numDeadEntries = 0;
-}
-
-/*
- * Free the table.
- */
-void mzHashTableFree(HashTable* pHashTable)
-{
- if (pHashTable == NULL)
- return;
- mzHashTableClear(pHashTable);
- free(pHashTable->pEntries);
- free(pHashTable);
-}
-
-#ifndef NDEBUG
-/*
- * Count up the number of tombstone entries in the hash table.
- */
-static int countTombStones(HashTable* pHashTable)
-{
- int i, count;
-
- for (count = i = 0; i < pHashTable->tableSize; i++) {
- if (pHashTable->pEntries[i].data == HASH_TOMBSTONE)
- count++;
- }
- return count;
-}
-#endif
-
-/*
- * Resize a hash table. We do this when adding an entry increased the
- * size of the table beyond its comfy limit.
- *
- * This essentially requires re-inserting all elements into the new storage.
- *
- * If multiple threads can access the hash table, the table's lock should
- * have been grabbed before issuing the "lookup+add" call that led to the
- * resize, so we don't have a synchronization problem here.
- */
-static bool resizeHash(HashTable* pHashTable, int newSize)
-{
- HashEntry* pNewEntries;
- int i;
-
- assert(countTombStones(pHashTable) == pHashTable->numDeadEntries);
-
- pNewEntries = (HashEntry*) calloc(newSize, sizeof(HashTable));
- if (pNewEntries == NULL)
- return false;
-
- for (i = 0; i < pHashTable->tableSize; i++) {
- void* data = pHashTable->pEntries[i].data;
- if (data != NULL && data != HASH_TOMBSTONE) {
- int hashValue = pHashTable->pEntries[i].hashValue;
- int newIdx;
-
- /* probe for new spot, wrapping around */
- newIdx = hashValue & (newSize-1);
- while (pNewEntries[newIdx].data != NULL)
- newIdx = (newIdx + 1) & (newSize-1);
-
- pNewEntries[newIdx].hashValue = hashValue;
- pNewEntries[newIdx].data = data;
- }
- }
-
- free(pHashTable->pEntries);
- pHashTable->pEntries = pNewEntries;
- pHashTable->tableSize = newSize;
- pHashTable->numDeadEntries = 0;
-
- assert(countTombStones(pHashTable) == 0);
- return true;
-}
-
-/*
- * Look up an entry.
- *
- * We probe on collisions, wrapping around the table.
- */
-void* mzHashTableLookup(HashTable* pHashTable, unsigned int itemHash, void* item,
- HashCompareFunc cmpFunc, bool doAdd)
-{
- HashEntry* pEntry;
- HashEntry* pEnd;
- void* result = NULL;
-
- assert(pHashTable->tableSize > 0);
- assert(item != HASH_TOMBSTONE);
- assert(item != NULL);
-
- /* jump to the first entry and probe for a match */
- pEntry = &pHashTable->pEntries[itemHash & (pHashTable->tableSize-1)];
- pEnd = &pHashTable->pEntries[pHashTable->tableSize];
- while (pEntry->data != NULL) {
- if (pEntry->data != HASH_TOMBSTONE &&
- pEntry->hashValue == itemHash &&
- (*cmpFunc)(pEntry->data, item) == 0)
- {
- /* match */
- break;
- }
-
- pEntry++;
- if (pEntry == pEnd) { /* wrap around to start */
- if (pHashTable->tableSize == 1)
- break; /* edge case - single-entry table */
- pEntry = pHashTable->pEntries;
- }
- }
-
- if (pEntry->data == NULL) {
- if (doAdd) {
- pEntry->hashValue = itemHash;
- pEntry->data = item;
- pHashTable->numEntries++;
-
- /*
- * We've added an entry. See if this brings us too close to full.
- */
- if ((pHashTable->numEntries+pHashTable->numDeadEntries) * LOAD_DENOM
- > pHashTable->tableSize * LOAD_NUMER)
- {
- if (!resizeHash(pHashTable, pHashTable->tableSize * 2)) {
- /* don't really have a way to indicate failure */
- LOGE("Dalvik hash resize failure\n");
- abort();
- }
- /* note "pEntry" is now invalid */
- }
-
- /* full table is bad -- search for nonexistent never halts */
- assert(pHashTable->numEntries < pHashTable->tableSize);
- result = item;
- } else {
- assert(result == NULL);
- }
- } else {
- result = pEntry->data;
- }
-
- return result;
-}
-
-/*
- * Remove an entry from the table.
- *
- * Does NOT invoke the "free" function on the item.
- */
-bool mzHashTableRemove(HashTable* pHashTable, unsigned int itemHash, void* item)
-{
- HashEntry* pEntry;
- HashEntry* pEnd;
-
- assert(pHashTable->tableSize > 0);
-
- /* jump to the first entry and probe for a match */
- pEntry = &pHashTable->pEntries[itemHash & (pHashTable->tableSize-1)];
- pEnd = &pHashTable->pEntries[pHashTable->tableSize];
- while (pEntry->data != NULL) {
- if (pEntry->data == item) {
- pEntry->data = HASH_TOMBSTONE;
- pHashTable->numEntries--;
- pHashTable->numDeadEntries++;
- return true;
- }
-
- pEntry++;
- if (pEntry == pEnd) { /* wrap around to start */
- if (pHashTable->tableSize == 1)
- break; /* edge case - single-entry table */
- pEntry = pHashTable->pEntries;
- }
- }
-
- return false;
-}
-
-/*
- * Execute a function 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)
-{
- int i, val;
-
- for (i = 0; i < pHashTable->tableSize; i++) {
- HashEntry* pEnt = &pHashTable->pEntries[i];
-
- if (pEnt->data != NULL && pEnt->data != HASH_TOMBSTONE) {
- val = (*func)(pEnt->data, arg);
- if (val != 0)
- return val;
- }
- }
-
- return 0;
-}
-
-
-/*
- * Look up an entry, counting the number of times we have to probe.
- *
- * Returns -1 if the entry wasn't found.
- */
-int countProbes(HashTable* pHashTable, unsigned int itemHash, const void* item,
- HashCompareFunc cmpFunc)
-{
- HashEntry* pEntry;
- HashEntry* pEnd;
- int count = 0;
-
- assert(pHashTable->tableSize > 0);
- assert(item != HASH_TOMBSTONE);
- assert(item != NULL);
-
- /* jump to the first entry and probe for a match */
- pEntry = &pHashTable->pEntries[itemHash & (pHashTable->tableSize-1)];
- pEnd = &pHashTable->pEntries[pHashTable->tableSize];
- while (pEntry->data != NULL) {
- if (pEntry->data != HASH_TOMBSTONE &&
- pEntry->hashValue == itemHash &&
- (*cmpFunc)(pEntry->data, item) == 0)
- {
- /* match */
- break;
- }
-
- pEntry++;
- if (pEntry == pEnd) { /* wrap around to start */
- if (pHashTable->tableSize == 1)
- break; /* edge case - single-entry table */
- pEntry = pHashTable->pEntries;
- }
-
- count++;
- }
- if (pEntry->data == NULL)
- return -1;
-
- return count;
-}
-
-/*
- * Evaluate the amount of probing required for the specified hash table.
- *
- * We do this by running through all entries in the hash table, computing
- * the hash value and then doing a lookup.
- *
- * The caller should lock the table before calling here.
- */
-void mzHashTableProbeCount(HashTable* pHashTable, HashCalcFunc calcFunc,
- HashCompareFunc cmpFunc)
-{
- int numEntries, minProbe, maxProbe, totalProbe;
- HashIter iter;
-
- numEntries = maxProbe = totalProbe = 0;
- minProbe = 65536*32767;
-
- for (mzHashIterBegin(pHashTable, &iter); !mzHashIterDone(&iter);
- mzHashIterNext(&iter))
- {
- const void* data = (const void*)mzHashIterData(&iter);
- int count;
-
- count = countProbes(pHashTable, (*calcFunc)(data), data, cmpFunc);
-
- numEntries++;
-
- if (count < minProbe)
- minProbe = count;
- if (count > maxProbe)
- maxProbe = count;
- totalProbe += count;
- }
-
- LOGV("Probe: min=%d max=%d, total=%d in %d (%d), avg=%.3f\n",
- minProbe, maxProbe, totalProbe, numEntries, pHashTable->tableSize,
- (float) totalProbe / (float) numEntries);
-}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-01 23:04:52 +0100