---

sc_hash.cpp

Go to the documentation of this file.

/*****************************************************************************

  The following code is derived, directly or indirectly, from the SystemC
  source code Copyright (c) 1996-2004 by all Contributors.
  All Rights reserved.

  The contents of this file are subject to the restrictions and limitations
  set forth in the SystemC Open Source License Version 2.3 (the "License");
  You may not use this file except in compliance with such restrictions and
  limitations. You may obtain instructions on how to receive a copy of the
  License at http://www.systemc.org/. Software distributed by Contributors
  under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
  ANY KIND, either express or implied. See the License for the specific
  language governing rights and limitations under the License.

 *****************************************************************************/

/*****************************************************************************

  sc_hash.cpp -- Implementation of a chained hash table with MTF
                 (move-to-front).

  Original Author: Stan Y. Liao, Synopsys, Inc.

 *****************************************************************************/

/*****************************************************************************

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.

      Name, Affiliation, Date:
  Description of Modification:

 *****************************************************************************/


#include <assert.h>
#include <stdlib.h>

#include "systemc/kernel/sc_cmnhdr.h"
#include "systemc/utils/sc_hash.h"
#include "systemc/utils/sc_mempool.h"


const double PHASH_DEFAULT_GROW_FACTOR     = 2.0;

class sc_phash_elem {
    friend class sc_phash_base;
    friend class sc_phash_base_iter;

private:
    void* key;
    void* contents;
    sc_phash_elem* next;

    sc_phash_elem( void* k, void* c, sc_phash_elem* n )
        : key(k), contents(c), next(n) { }
    sc_phash_elem() { }
    ~sc_phash_elem() { }

    static void* operator new(size_t sz)            { return sc_mempool::allocate(sz); }
    static void operator delete(void* p, size_t sz) { sc_mempool::release(p, sz);      }
};


sc_phash_base::sc_phash_base(
    void* def,
    int size,
    int density,
    double grow,
    bool reorder,
    unsigned (*hash_fn)(const void*),
    int (*cmp_fn)(const void*, const void*)
)
{
    default_value = def;
    hash          = hash_fn;
    num_entries   = 0;
    max_density   = density;
    grow_factor   = grow;
    reorder_flag  = reorder;

    if (size <= 0)
        size = PHASH_DEFAULT_INIT_TABLE_SIZE;
    else if ((size % 2) == 0)
        size += 1;
    num_bins = size;
    bins = new sc_phash_elem*[size];
    for (int i = 0; i < size; ++i)
        bins[i] = 0;

    set_cmpr_fn(cmp_fn);
}

void
sc_phash_base::set_cmpr_fn(cmpr_fn_t c)
{
    cmpr = c;
}

void
sc_phash_base::set_hash_fn(hash_fn_t h)
{
    hash = h;
}

sc_phash_base::~sc_phash_base()
{
    sc_phash_elem* ptr;
    sc_phash_elem* next;

    for (int i = 0; i < num_bins; ++i) {
        ptr = bins[i];
        while (ptr != 0) {
            next = ptr->next;
            delete ptr;
            ptr = next;
        }
    }
    delete[] bins;
}

void
sc_phash_base::rehash()
{
    sc_phash_elem* ptr;
    sc_phash_elem* next;
    sc_phash_elem** old_bins = bins;

    int old_num_bins = num_bins;
    unsigned hash_val;

    num_bins = (int) (grow_factor * old_num_bins);
    if (num_bins % 2 == 0)
        ++num_bins;

    num_entries = 0;
    bins = new sc_phash_elem*[num_bins];
    memset( bins, 0, sizeof(sc_phash_elem*) * num_bins );

    for (int i = 0; i < old_num_bins; ++i) {
        ptr = old_bins[i];
        while (ptr != 0) {
            next = ptr->next;
            hash_val = do_hash(ptr->key);
            ptr->next = bins[hash_val];
            bins[hash_val] = ptr;
            ++num_entries;
            ptr = next;
        }
    }
    delete[] old_bins;
}

sc_phash_elem*
sc_phash_base::find_entry_q( unsigned hash_val, const void* key, sc_phash_elem*** plast )
{
    sc_phash_elem** last = &(bins[hash_val]);
    sc_phash_elem*  ptr  = *last;

    /* The (ptr->key != key) here is meant by the "q" */
    while ((ptr != 0) && (ptr->key != key)) {
        /*                         ^^ right here */
        last = &(ptr->next);
        ptr  = *last;
    }
    if ((ptr != 0) && reorder_flag) {
        *last = ptr->next;
        ptr->next = bins[hash_val];
        bins[hash_val] = ptr;
        last = &(bins[hash_val]);
    }
    if (plast) *plast = last;
    return ptr;
}

sc_phash_elem*
sc_phash_base::find_entry_c( unsigned hash_val, const void* key, sc_phash_elem*** plast )
{
    sc_phash_elem** last = &(bins[hash_val]);
    sc_phash_elem*  ptr  = *last;

    while ((ptr != 0) && ((*cmpr)(ptr->key, key) != 0)) {
        last = &(ptr->next);
        ptr = *last;
    }
        /* Bring to front */
    if ((ptr != 0) && reorder_flag) {
        *last = ptr->next;
        ptr->next = bins[hash_val];
        bins[hash_val] = ptr;
        last = &(bins[hash_val]);
    }
    if (plast) *plast = last;
    return ptr;
}

sc_phash_elem*
sc_phash_base::add_direct( void* key, void* contents, unsigned hash_val )
{
    if (num_entries / num_bins >= max_density) {
        rehash();
        hash_val = do_hash(key);
    }

    sc_phash_elem* new_entry = new sc_phash_elem(key, contents, bins[hash_val]);
    bins[hash_val] = new_entry;
    ++num_entries;
    return new_entry;
}

void
sc_phash_base::erase()
{
    for (int i = 0; i < num_bins; ++i) {
        sc_phash_elem* ptr = bins[i];
        while (ptr != 0) {
            sc_phash_elem* next = ptr->next;
            delete ptr;
            ptr = next;
            --num_entries;
        }
        bins[i] = 0;
    }
    assert(num_entries == 0);
}

void
sc_phash_base::erase(void (*kfree)(void*))
{
    for (int i = 0; i < num_bins; ++i) {
        sc_phash_elem* ptr = bins[i];
        while (ptr != 0) {
            sc_phash_elem* next = ptr->next;
            (*kfree)(ptr->key);
            delete ptr;
            ptr = next;
            --num_entries;
        }
        bins[i] = 0;
    }
    assert(num_entries == 0);
}

void
sc_phash_base::copy( const sc_phash_base* b )
{
    erase();
    iterator iter((sc_phash_base*) b);  /* cast away the const */
    for ( ; ! iter.empty(); iter++)
        insert( iter.key(), iter.contents() );
}

void
sc_phash_base::copy(const sc_phash_base& b, void* (*kdup)(const void*), void (*kfree)(void*))
{
    erase(kfree);
    iterator iter((sc_phash_base&) b);
    for ( ; ! iter.empty(); iter++)
        insert( (*kdup)(iter.key()), iter.contents() );
}

int
sc_phash_base::insert( void* k, void* c )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem* ptr = find_entry( hash_val, k );
    if (ptr == 0) {
        (void) add_direct(k, c, hash_val);
        return 0;
    }
    else {
        ptr->contents = c;
        return 1;
    }
}

int
sc_phash_base::insert( void* k, void* c, void* (*kdup)(const void*) )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem* ptr = find_entry( hash_val, k );
    if (ptr == 0) {
        (void) add_direct((*kdup)(k), c, hash_val);
        return 0;
    }
    else {
        ptr->contents = c;
        return 1;
    }
}

int
sc_phash_base::insert_if_not_exists( void* k, void* c )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem* ptr = find_entry( hash_val, k );
    if (ptr == 0) {
        (void) add_direct( k, c, hash_val );
        return 0;
    }
    else
        return 1;
}

int
sc_phash_base::insert_if_not_exists( void* k, void* c, void* (*kdup)(const void*) )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem* ptr = find_entry( hash_val, k );
    if (ptr == 0) {
        (void) add_direct( (*kdup)(k), c, hash_val );
        return 0;
    }
    else
        return 1;
}

int
sc_phash_base::remove( const void* k )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem** last;
    sc_phash_elem*  ptr = find_entry( hash_val, k, &last );

    if (ptr == 0)
        return 0;

    assert(*last == ptr);
    *last = ptr->next;
    delete ptr;
    --num_entries;
    return 1;
}

int
sc_phash_base::remove( const void* k, void** pk, void** pc )
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem** last;
    sc_phash_elem*  ptr = find_entry( hash_val, k, &last );

    if (ptr == 0) {
        *pk = 0;
        *pc = 0;
        return 0;
    }
    else {
        *pk = ptr->key;
        *pc = ptr->contents;
    }

    assert(*last == ptr);
    *last = ptr->next;
    delete ptr;
    --num_entries;
    return 1;
}

int
sc_phash_base::remove(const void* k, void (*kfree)(void*))
{
    void* rk;
    void* rc;
    if (remove(k, &rk, &rc)) {
        (*kfree)(rk);
        return 1;
    }
    else
        return 0;
}

int
sc_phash_base::remove_by_contents( const void* c )
{
    sc_phash_elem** last;
    sc_phash_elem*  ptr;

    int num_removed = 0;
    for (int i = 0; i < num_bins; ++i) {
        last = &(bins[i]);
        ptr = *last;
        while (ptr != 0) {
            if (ptr->contents != c) {
                last = &(ptr->next);
                ptr  = *last;
            }
            else {
                *last = ptr->next;
                delete ptr;
                ptr = *last;
                --num_entries;
                ++num_removed;
            }
        }
    }
    return num_removed;
}

int
sc_phash_base::remove_by_contents( bool (*predicate)(const void* c, void* arg), void* arg )
{
    sc_phash_elem** last;
    sc_phash_elem*  ptr;

    int num_removed = 0;
    for (int i = 0; i < num_bins; ++i) {
        last = &(bins[i]);
        ptr = *last;
        while (ptr != 0) {
            if (! (*predicate)(ptr->contents, arg)) {
                last = &(ptr->next);
                ptr  = *last;
            }
            else {
                *last = ptr->next;
                delete ptr;
                ptr = *last;
                --num_entries;
                ++num_removed;
            }
        }
    }
    return num_removed;
}

int
sc_phash_base::remove_by_contents( const void* c, void (*kfree)(void*) )
{
    sc_phash_elem** last;
    sc_phash_elem*  ptr;

    int num_removed = 0;
    for (int i = 0; i < num_bins; ++i) {
        last = &(bins[i]);
        ptr = *last;
        while (ptr != 0) {
            if (ptr->contents != c) {
                last = &(ptr->next);
                ptr  = *last;
            }
            else {
                *last = ptr->next;
                (*kfree)(ptr->key);
                delete ptr;
                ptr = *last;
                --num_entries;
                ++num_removed;
            }
        }
    }
    return num_removed;
}

int
sc_phash_base::remove_by_contents( bool (*predicate)(const void*, void*), void* arg, void (*kfree)(void*))
{
    sc_phash_elem** last;
    sc_phash_elem*  ptr;

    int num_removed = 0;
    for (int i = 0; i < num_bins; ++i) {
        last = &(bins[i]);
        ptr = *last;
        while (ptr != 0) {
            if (! (*predicate)(ptr->contents, arg)) {
                last = &(ptr->next);
                ptr  = *last;
            }
            else {
                *last = ptr->next;
                (*kfree)(ptr->key);
                delete ptr;
                ptr = *last;
                --num_entries;
                ++num_removed;
            }
        }
    }
    return num_removed;
}

int
sc_phash_base::lookup( const void* k, void** c_ptr ) const
{
    unsigned hash_val = do_hash(k);
    sc_phash_elem* ptr = find_entry( hash_val, k );
    if (ptr == 0) {
        if (c_ptr != 0) *c_ptr = default_value;
        return 0;
    }
    else {
        if (c_ptr != 0) *c_ptr = ptr->contents;
        return 1;
    }
}

void*
sc_phash_base::operator[]( const void* key ) const
{
    void* contents;
    lookup( key, &contents );
    return contents;
}

/***************************************************************************/

void
sc_phash_base_iter::reset( sc_phash_base* t )
{
    table = t;
    index = 0;
    entry = 0;
    next  = 0;

    for (int i = index; i < table->num_bins; ++i) {
        if (table->bins[i] != 0) {
            index = i + 1;
            last  = &(table->bins[i]);
            entry = *last;
            next  = entry->next;
            break;
        }
    }
}

bool
sc_phash_base_iter::empty() const
{
    return (entry == 0);
}

void
sc_phash_base_iter::step()
{
    if (entry) {
        last = &(entry->next);
    }
    entry = next;
    if (! entry) {
        for (int i = index; i < table->num_bins; ++i) {
            if (table->bins[i] != 0) {
                index = i + 1;
                last = &(table->bins[i]);
                entry = *last;
                next = entry->next;
                break;
            }
        }
    }
    else {
        next = entry->next;
    }
}

void
sc_phash_base_iter::remove()
{
    delete entry;
    *last = next;
    entry = 0;
    --table->num_entries;
    step();
}

void
sc_phash_base_iter::remove(void (*kfree)(void*))
{
    (*kfree)(entry->key);
    delete entry;
    *last = next;
    entry = 0;
    --table->num_entries;
    step();
}

void*
sc_phash_base_iter::key() const
{
    return entry->key;
}

void*
sc_phash_base_iter::contents() const
{
    return entry->contents;
}

void*
sc_phash_base_iter::set_contents( void* c )
{
    return entry->contents = c;
}

/****************************************************************************/

unsigned 
default_ptr_hash_fn(const void* p)
{
    return ((unsigned)(p) >> 2) * 2654435789U;

}

unsigned
default_int_hash_fn(const void* p)
{
    return (unsigned)(p) * 3141592661U;
}


unsigned
default_str_hash_fn(const void* p)
{
    if (!p) return 0;

    const char* x = (const char*) p;
    unsigned int h = 0;
    unsigned int g;

    while (*x != 0) {
        h = (h << 4) + *x++;
        if ((g = h & 0xf0000000) != 0)
            h = (h ^ (g >> 24)) ^ g;
    }
    return h;
}

int
sc_strhash_cmp( const void* a, const void* b )
{
    return strcmp( (const char*) a, (const char*) b );
}

void*
sc_strhash_kdup(const void* k)
{
    return strdup((const char*) k);
}

void
sc_strhash_kfree(void* k)
{
    if (k) free((char*) k);
}

---