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/* Copyright (C) 2021 Free Software Foundation, Inc.
Contributed by Oracle.
This file is part of GNU Binutils.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
/*
* Cache Map implementation.
*
* Cache Map makes the following assumptions:
* - Cache Map is used for very fast but not guaranteed mapping;
* - only REL_EQ Relation can be used;
* - all objects used as keys or values has to be managed
* outside CacheMap (f.e. deletion);
* - (Key_t)0 is invalid key;
* - (Value_t)0 is invalid value;
* - <TBC>
*/
#ifndef _DBE_CACHEMAP_H
#define _DBE_CACHEMAP_H
#include <assert.h>
#include <vec.h>
#include <Map.h>
template <typename Key_t, typename Value_t>
class CacheMap : public Map<Key_t, Value_t>
{
public:
CacheMap ();
~CacheMap ();
void put (Key_t key, Value_t val);
Value_t get (Key_t key);
Value_t get (Key_t key, typename Map<Key_t, Value_t>::Relation rel);
Value_t
remove (Key_t key);
private:
struct Entry
{
Key_t key;
Value_t val;
Entry ()
{
key = (Key_t) 0;
}
};
static const int INIT_SIZE;
static const int MAX_SIZE;
static unsigned hash (Key_t key);
Entry *getEntry (Key_t key);
int cursize;
int nputs;
int nchunks;
Entry **chunks;
};
template <typename Key_t, typename Value_t>
const int CacheMap<Key_t, Value_t>::INIT_SIZE = 1 << 14;
template <typename Key_t, typename Value_t>
const int CacheMap<Key_t, Value_t>::MAX_SIZE = 1 << 20;
template <typename Key_t, typename Value_t>CacheMap<Key_t, Value_t>
::CacheMap ()
{
cursize = INIT_SIZE;
chunks = new Entry*[32];
nchunks = 0;
chunks[nchunks++] = new Entry[cursize];
nputs = 0;
}
template <typename Key_t, typename Value_t>
CacheMap<Key_t, Value_t>::~CacheMap ()
{
for (int i = 0; i < nchunks; i++)
delete[] chunks[i];
delete[] chunks;
}
template <typename Key_t, typename Value_t>
unsigned
CacheMap<Key_t, Value_t>::hash (Key_t key)
{
unsigned h = (unsigned) key ^ (unsigned) (key >> 32);
h ^= (h >> 20) ^ (h >> 12);
return h ^ (h >> 7) ^ (h >> 4);
}
template <typename Key_t, typename Value_t>
void
CacheMap<Key_t, Value_t>::put (Key_t key, Value_t val)
{
if (nputs >= cursize && cursize < MAX_SIZE)
{
// Allocate new chunk for entries.
chunks[nchunks++] = new Entry[cursize];
cursize *= 2;
// Copy all old entries to the newly allocated chunk
Entry *newchunk = chunks[nchunks - 1];
int prevsz = 0;
int nextsz = INIT_SIZE;
for (int i = 0; i < nchunks - 1; i++)
{
Entry *oldchunk = chunks[i];
for (int j = prevsz; j < nextsz; j++)
newchunk[j] = oldchunk[j - prevsz];
prevsz = nextsz;
nextsz *= 2;
}
}
Entry *entry = getEntry (key);
entry->key = key;
entry->val = val;
nputs++;
}
template <typename Key_t, typename Value_t>
typename CacheMap<Key_t, Value_t>::Entry *
CacheMap<Key_t, Value_t>::getEntry (Key_t key)
{
unsigned idx = hash (key);
int i = nchunks - 1;
int j = cursize / 2;
for (; i > 0; i -= 1, j /= 2)
if (idx & j)
break;
if (i == 0)
j *= 2;
return &chunks[i][idx & (j - 1)];
}
template <typename Key_t, typename Value_t>
Value_t
CacheMap<Key_t, Value_t>::get (Key_t key)
{
Entry *entry = getEntry (key);
return entry->key == key ? entry->val : (Value_t) 0;
}
template <typename Key_t, typename Value_t>
Value_t
CacheMap<Key_t, Value_t>::get (Key_t key, typename Map<Key_t, Value_t>::Relation rel)
{
if (rel != Map<Key_t, Value_t>::REL_EQ)
return (Value_t) 0;
return get (key);
}
template <typename Key_t, typename Value_t>
Value_t
CacheMap<Key_t, Value_t>::remove (Key_t key)
{
Entry *entry = getEntry (key);
Value_t res = (Value_t) 0;
if (entry->key == key)
{
res = entry->val;
entry->val = (Value_t) 0;
}
return res;
}
#endif
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