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add dox to SkTDynamicHash, fix typo of Key instead of KEY

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BUG=
R=mtklein@google.com

Review URL: https://codereview.chromium.org/21028008

git-svn-id: http://skia.googlecode.com/svn/trunk@10465 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com 2013-07-31 18:02:55 +00:00
parent e027a6ed9b
commit b14ecdaeea
1 changed files with 19 additions and 8 deletions
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27
src/core/SkTDynamicHash.h
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@ -10,21 +10,32 @@
#include "SkTypes.h"
template <typename T, typename KEY, const KEY& (KEY_FROM_T)(const T&),
uint32_t (HASH_FROM_KEY)(const Key&), bool (EQ_T_KEY)(const T&, const Key&)>
template <typename T,
typename KEY,
const KEY& (KEY_FROM_T)(const T&),
uint32_t (HASH_FROM_KEY)(const KEY&),
bool (EQ_T_KEY)(const T&, const KEY&)>
class SkTDynamicHash {
private:
T* fStorage[4];
T* fStorage[4]; // cheap storage for small arrays
T** fArray;
int fCapacity;
int fCountUsed;
int fCountDeleted;
int fCapacity; // number of slots in fArray. Must be pow2
int fCountUsed; // number of valid entries in fArray
int fCountDeleted; // number of deletedValue() entries in fArray
// Need an illegal ptr value different from NULL (which we use to
// signal empty/unused.
const T* deletedValue() const { return reinterpret_cast<const T*>(-1); }
// fCapacity is a pow2, so that minus one is a clean mask to grab
// the low bits of hash to use as an index.
uint32_t hashMask() const { return fCapacity - 1; }
int hashToIndex(uint32_t hash) const {
return ((hash >> 16) ^ hash) & (fCapacity - 1);
// this 16bit fold may be overkill, if we trust that hash is good
return ((hash >> 16) ^ hash) & this->hashMask();
}
public:
SkTDynamicHash() {
sk_bzero(fStorage, sizeof(fStorage));
@ -112,7 +123,7 @@ public:
}
private:
int countCollisions(const Key& key) const {
int countCollisions(const KEY& key) const {
const T* const deleted = this->deletedValue();
const unsigned mask = this->hashMask();
int index = this->hashToIndex(HASH_FROM_KEY(key));