unicorn/qemu/glib_compat.c

/*
glib_compat.c replacement functionality for glib code used in qemu
Copyright (C) 2016 Chris Eagle cseagle at gmail dot com

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 2
of the License, 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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

// Part of this code was lifted from glib-2.28.0.
// Glib license is available in COPYING_GLIB file in root directory.

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>

#include "glib_compat.h"

#define MAX(a, b)  (((a) > (b)) ? (a) : (b))
#ifndef _WIN64
#define GPOINTER_TO_UINT(p) ((guint) (p))
#else
#define GPOINTER_TO_UINT(p) ((guint) (guint64) (p))
#endif
#define G_MAXINT    INT_MAX

/* All functions below added to eliminate GLIB dependency */

/* hashing and equality functions */
// Hash functions lifted glib-2.28.0/glib/ghash.c

/**
 * g_direct_hash:
 * @v: a #gpointer key
 *
 * Converts a gpointer to a hash value.
 * It can be passed to g_hash_table_new() as the @hash_func parameter,
 * when using pointers as keys in a #GHashTable.
 *
 * Returns: a hash value corresponding to the key.
 */
static guint g_direct_hash (gconstpointer v)
{
  return GPOINTER_TO_UINT (v);
}

// g_str_hash() is lifted glib-2.28.0/glib/gstring.c
/**
 * g_str_hash:
 * @v: a string key
 *
 * Converts a string to a hash value.
 *
 * This function implements the widely used "djb" hash apparently posted
 * by Daniel Bernstein to comp.lang.c some time ago.  The 32 bit
 * unsigned hash value starts at 5381 and for each byte 'c' in the
 * string, is updated: <literal>hash = hash * 33 + c</literal>.  This
 * function uses the signed value of each byte.
 *
 * It can be passed to g_hash_table_new() as the @hash_func parameter,
 * when using strings as keys in a #GHashTable.
 *
 * Returns: a hash value corresponding to the key
 **/
guint g_str_hash (gconstpointer v)
{
  const signed char *p;
  guint32 h = 5381;

  for (p = v; *p != '\0'; p++)
    h = (h << 5) + h + *p;

  return h;
}

gboolean g_str_equal(gconstpointer v1, gconstpointer v2)
{
   return strcmp((const char*)v1, (const char*)v2) == 0;
}

// g_int_hash() is lifted from glib-2.28.0/glib/gutils.c
/**
 * g_int_hash:
 * @v: a pointer to a #gint key
 *
 * Converts a pointer to a #gint to a hash value.
 * It can be passed to g_hash_table_new() as the @hash_func parameter,
 * when using pointers to integers values as keys in a #GHashTable.
 *
 * Returns: a hash value corresponding to the key.
 */
guint g_int_hash (gconstpointer v)
{
  return *(const gint*) v;
}

gboolean g_int_equal(gconstpointer v1, gconstpointer v2)
{
   return *((const gint*)v1) == *((const gint*)v2);
}

/* Doubly-linked list */

GList *g_list_first(GList *list)
{
   if (list == NULL) return NULL;
   while (list->prev) list = list->prev;
   return list;
}

void g_list_foreach(GList *list, GFunc func, gpointer user_data)
{
   GList *lp;
   for (lp = list; lp; lp = lp->next) {
      (*func)(lp->data, user_data);
   }
}

void g_list_free(GList *list)
{
   GList *lp, *next, *prev = NULL;
   if (list) prev = list->prev;
   for (lp = list; lp; lp = next) {
      next = lp->next;
      free(lp);
   }
   for (lp = prev; lp; lp = prev) {
      prev = lp->prev;
      free(lp);
   }
}

GList *g_list_insert_sorted(GList *list, gpointer data, GCompareFunc compare)
{
   GList *i;
   GList *n = (GList*)g_malloc(sizeof(GList));
   n->data = data;
   if (list == NULL) {
      n->next = n->prev = NULL;
      return n;
   }
   for (i = list; i; i = i->next) {
      n->prev = i->prev;
      if ((*compare)(data, i->data) <= 0) {
         n->next = i;
         i->prev = n;
         if (i == list) return n;
         else return list;
      }
   }
   n->prev = n->prev->next;
   n->next = NULL;
   n->prev->next = n;
   return list;
}

GList *g_list_prepend(GList *list, gpointer data)
{
   GList *n = (GList*)g_malloc(sizeof(GList));
   n->next = list;
   n->prev = NULL;
   n->data = data;
   return n;
}

GList *g_list_remove_link(GList *list, GList *llink)
{
   if (llink) {
      if (llink == list) list = list->next;
      if (llink->prev) llink->prev->next = llink->next;
      if (llink->next) llink->next->prev = llink->prev;
   }
   return list;
}

// code copied from glib/glist.c, version 2.28.0
static GList *g_list_sort_merge(GList *l1,
		   GList     *l2,
		   GFunc     compare_func,
		   gpointer  user_data)
{
  GList list, *l, *lprev;
  gint cmp;

  l = &list;
  lprev = NULL;

  while (l1 && l2)
    {
      cmp = ((GCompareDataFunc) compare_func) (l1->data, l2->data, user_data);

      if (cmp <= 0)
        {
	  l->next = l1;
	  l1 = l1->next;
        }
      else
	{
	  l->next = l2;
	  l2 = l2->next;
        }
      l = l->next;
      l->prev = lprev;
      lprev = l;
    }
  l->next = l1 ? l1 : l2;
  l->next->prev = l;

  return list.next;
}

static GList *g_list_sort_real(GList *list,
		  GFunc     compare_func,
		  gpointer  user_data)
{
  GList *l1, *l2;

  if (!list)
    return NULL;
  if (!list->next)
    return list;

  l1 = list;
  l2 = list->next;

  while ((l2 = l2->next) != NULL)
    {
      if ((l2 = l2->next) == NULL)
	break;
      l1 = l1->next;
    }
  l2 = l1->next;
  l1->next = NULL;

  return g_list_sort_merge (g_list_sort_real (list, compare_func, user_data),
			    g_list_sort_real (l2, compare_func, user_data),
			    compare_func,
			    user_data);
}

/**
 * g_list_sort:
 * @list: a #GList
 * @compare_func: the comparison function used to sort the #GList.
 *     This function is passed the data from 2 elements of the #GList
 *     and should return 0 if they are equal, a negative value if the
 *     first element comes before the second, or a positive value if
 *     the first element comes after the second.
 *
 * Sorts a #GList using the given comparison function.
 *
 * Returns: the start of the sorted #GList
 */
/**
 * GCompareFunc:
 * @a: a value.
 * @b: a value to compare with.
 * @Returns: negative value if @a &lt; @b; zero if @a = @b; positive
 *           value if @a > @b.
 *
 * Specifies the type of a comparison function used to compare two
 * values.  The function should return a negative integer if the first
 * value comes before the second, 0 if they are equal, or a positive
 * integer if the first value comes after the second.
 **/
GList *g_list_sort (GList *list, GCompareFunc  compare_func)
{
    return g_list_sort_real (list, (GFunc) compare_func, NULL);
}

/* END of g_list related functions */

/* Singly-linked list */

GSList *g_slist_append(GSList *list, gpointer data)
{
   GSList *head = list;
   if (list) {
      while (list->next) list = list->next;
      list->next = (GSList*)g_malloc(sizeof(GSList));
      list = list->next;
   } else {
      head = list = (GSList*)g_malloc(sizeof(GSList));
   }
   list->data = data;
   list->next = NULL;
   return head;   
}

void g_slist_foreach(GSList *list, GFunc func, gpointer user_data)
{
   GSList *lp;
   for (lp = list; lp; lp = lp->next) {
      (*func)(lp->data, user_data);
   }
}

void g_slist_free(GSList *list)
{
   GSList *lp, *next;
   for (lp = list; lp; lp = next) {
      next = lp->next;
      free(lp);
   }
}

GSList *g_slist_prepend(GSList *list, gpointer data)
{
   GSList *head = (GSList*)g_malloc(sizeof(GSList));
   head->next = list;
   head->data = data;
   return head;   
}

static GSList *g_slist_sort_merge (GSList *l1,
                    GSList *l2,
                    GFunc compare_func,
                    gpointer user_data)
{
  GSList list, *l;
  gint cmp;

  l=&list;

  while (l1 && l2)
    {
      cmp = ((GCompareDataFunc) compare_func) (l1->data, l2->data, user_data);

      if (cmp <= 0)
        {
          l=l->next=l1;
          l1=l1->next;
        }
      else
        {
          l=l->next=l2;
          l2=l2->next;
        }
    }
  l->next= l1 ? l1 : l2;

  return list.next;
}

static GSList *g_slist_sort_real (GSList *list,
                   GFunc compare_func,
                   gpointer user_data)
{
  GSList *l1, *l2;

  if (!list)
    return NULL;
  if (!list->next)
    return list;

  l1 = list;
  l2 = list->next;

  while ((l2 = l2->next) != NULL)
    {
      if ((l2 = l2->next) == NULL)
        break;
      l1=l1->next;
    }
  l2 = l1->next;
  l1->next = NULL;

  return g_slist_sort_merge (g_slist_sort_real (list, compare_func, user_data),
                             g_slist_sort_real (l2, compare_func, user_data),
                             compare_func,
                             user_data);
}

/**
 * g_slist_sort:
 * @list: a #GSList
 * @compare_func: the comparison function used to sort the #GSList.
 *     This function is passed the data from 2 elements of the #GSList
 *     and should return 0 if they are equal, a negative value if the
 *     first element comes before the second, or a positive value if
 *     the first element comes after the second.
 *
 * Sorts a #GSList using the given comparison function.
 *
 * Returns: the start of the sorted #GSList
 */
GSList *g_slist_sort (GSList *list,
              GCompareFunc  compare_func)
{
  return g_slist_sort_real (list, (GFunc) compare_func, NULL);
}

/* END of g_slist related functions */

// Hash functions lifted glib-2.28.0/glib/ghash.c

#define HASH_TABLE_MIN_SHIFT 3  /* 1 << 3 == 8 buckets */

typedef struct _GHashNode GHashNode;

struct _GHashNode {
  gpointer   key;
  gpointer   value;

  /* If key_hash == 0, node is not in use
   * If key_hash == 1, node is a tombstone
   * If key_hash >= 2, node contains data */
  guint      key_hash;
};

struct _GHashTable {
  gint             size;
  gint             mod;
  guint            mask;
  gint             nnodes;
  gint             noccupied;  /* nnodes + tombstones */
  GHashNode       *nodes;
  GHashFunc        hash_func;
  GEqualFunc       key_equal_func;
  volatile gint    ref_count;
  GDestroyNotify   key_destroy_func;
  GDestroyNotify   value_destroy_func;
};

/**
 * g_hash_table_destroy:
 * @hash_table: a #GHashTable.
 *
 * Destroys all keys and values in the #GHashTable and decrements its
 * reference count by 1. If keys and/or values are dynamically allocated,
 * you should either free them first or create the #GHashTable with destroy
 * notifiers using g_hash_table_new_full(). In the latter case the destroy
 * functions you supplied will be called on all keys and values during the
 * destruction phase.
 **/
void g_hash_table_destroy (GHashTable *hash_table)
{
  if (hash_table == NULL) return;
  if (hash_table->ref_count == 0) return;

  g_hash_table_remove_all (hash_table);
  g_hash_table_unref (hash_table);
}

/**
 * g_hash_table_find:
 * @hash_table: a #GHashTable.
 * @predicate:  function to test the key/value pairs for a certain property.
 * @user_data:  user data to pass to the function.
 *
 * Calls the given function for key/value pairs in the #GHashTable until
 * @predicate returns %TRUE.  The function is passed the key and value of
 * each pair, and the given @user_data parameter. The hash table may not
 * be modified while iterating over it (you can't add/remove items).
 *
 * Note, that hash tables are really only optimized for forward lookups,
 * i.e. g_hash_table_lookup().
 * So code that frequently issues g_hash_table_find() or
 * g_hash_table_foreach() (e.g. in the order of once per every entry in a
 * hash table) should probably be reworked to use additional or different
 * data structures for reverse lookups (keep in mind that an O(n) find/foreach
 * operation issued for all n values in a hash table ends up needing O(n*n)
 * operations).
 *
 * Return value: The value of the first key/value pair is returned, for which
 * func evaluates to %TRUE. If no pair with the requested property is found,
 * %NULL is returned.
 *
 * Since: 2.4
 **/
gpointer g_hash_table_find (GHashTable      *hash_table,
                   GHRFunc          predicate,
                   gpointer         user_data)
{
  gint i;

  if (hash_table == NULL) return NULL;
  if (predicate == NULL) return NULL;

  for (i = 0; i < hash_table->size; i++)
    {
      GHashNode *node = &hash_table->nodes [i];

      if (node->key_hash > 1 && predicate (node->key, node->value, user_data))
        return node->value;
    }

  return NULL;
}

/**
 * g_hash_table_foreach:
 * @hash_table: a #GHashTable.
 * @func: the function to call for each key/value pair.
 * @user_data: user data to pass to the function.
 *
 * Calls the given function for each of the key/value pairs in the
 * #GHashTable.  The function is passed the key and value of each
 * pair, and the given @user_data parameter.  The hash table may not
 * be modified while iterating over it (you can't add/remove
 * items). To remove all items matching a predicate, use
 * g_hash_table_foreach_remove().
 *
 * See g_hash_table_find() for performance caveats for linear
 * order searches in contrast to g_hash_table_lookup().
 **/
void g_hash_table_foreach (GHashTable *hash_table,
                      GHFunc      func,
                      gpointer    user_data)
{
  gint i;

  if (hash_table == NULL) return;
  if (func == NULL) return;

  for (i = 0; i < hash_table->size; i++)
    {
      GHashNode *node = &hash_table->nodes [i];

      if (node->key_hash > 1)
        (* func) (node->key, node->value, user_data);
    }
}

/*
 * g_hash_table_lookup_node_for_insertion:
 * @hash_table: our #GHashTable
 * @key: the key to lookup against
 * @hash_return: key hash return location
 * Return value: index of the described #GHashNode
 *
 * Performs a lookup in the hash table, preserving extra information
 * usually needed for insertion.
 *
 * This function first computes the hash value of the key using the
 * user's hash function.
 *
 * If an entry in the table matching @key is found then this function
 * returns the index of that entry in the table, and if not, the
 * index of an unused node (empty or tombstone) where the key can be
 * inserted.
 *
 * The computed hash value is returned in the variable pointed to
 * by @hash_return. This is to save insertions from having to compute
 * the hash record again for the new record.
 */
static inline guint g_hash_table_lookup_node_for_insertion (GHashTable    *hash_table,
                                        gconstpointer  key,
                                        guint         *hash_return)
{
  GHashNode *node;
  guint node_index;
  guint hash_value;
  guint first_tombstone;
  gboolean have_tombstone = FALSE;
  guint step = 0;

  /* Empty buckets have hash_value set to 0, and for tombstones, it's 1.
   * We need to make sure our hash value is not one of these. */

  hash_value = (* hash_table->hash_func) (key);
  if (hash_value <= 1)
    hash_value = 2;

  *hash_return = hash_value;

  node_index = hash_value % hash_table->mod;
  node = &hash_table->nodes [node_index];

  while (node->key_hash)
    {
      /*  We first check if our full hash values
       *  are equal so we can avoid calling the full-blown
       *  key equality function in most cases.
       */

      if (node->key_hash == hash_value)
        {
          if (hash_table->key_equal_func)
            {
              if (hash_table->key_equal_func (node->key, key))
                return node_index;
            }
          else if (node->key == key)
            {
              return node_index;
            }
        }
      else if (node->key_hash == 1 && !have_tombstone)
        {
          first_tombstone = node_index;
          have_tombstone = TRUE;
        }

      step++;
      node_index += step;
      node_index &= hash_table->mask;
      node = &hash_table->nodes [node_index];
    }

  if (have_tombstone)
    return first_tombstone;

  return node_index;
}

/* Each table size has an associated prime modulo (the first prime
 * lower than the table size) used to find the initial bucket. Probing
 * then works modulo 2^n. The prime modulo is necessary to get a
 * good distribution with poor hash functions. */
static const gint prime_mod [] = {
  1,          /* For 1 << 0 */
  2,
  3,
  7,
  13,
  31,
  61,
  127,
  251,
  509,
  1021,
  2039,
  4093,
  8191,
  16381,
  32749,
  65521,      /* For 1 << 16 */
  131071,
  262139,
  524287,
  1048573,
  2097143,
  4194301,
  8388593,
  16777213,
  33554393,
  67108859,
  134217689,
  268435399,
  536870909,
  1073741789,
  2147483647  /* For 1 << 31 */
};

static void g_hash_table_set_shift (GHashTable *hash_table, gint shift)
{
  gint i;
  guint mask = 0;

  hash_table->size = 1 << shift;
  hash_table->mod  = prime_mod [shift];

  for (i = 0; i < shift; i++)
    {
      mask <<= 1;
      mask |= 1;
    }

  hash_table->mask = mask;
}

static gint g_hash_table_find_closest_shift (gint n)
{
  gint i;

  for (i = 0; n; i++)
    n >>= 1;

  return i;
}

static void g_hash_table_set_shift_from_size (GHashTable *hash_table, gint size)
{
  gint shift;

  shift = g_hash_table_find_closest_shift (size);
  shift = MAX (shift, HASH_TABLE_MIN_SHIFT);

  g_hash_table_set_shift (hash_table, shift);
}

/*
 * g_hash_table_resize:
 * @hash_table: our #GHashTable
 *
 * Resizes the hash table to the optimal size based on the number of
 * nodes currently held.  If you call this function then a resize will
 * occur, even if one does not need to occur.  Use
 * g_hash_table_maybe_resize() instead.
 *
 * This function may "resize" the hash table to its current size, with
 * the side effect of cleaning up tombstones and otherwise optimizing
 * the probe sequences.
 */
static void g_hash_table_resize (GHashTable *hash_table)
{
  GHashNode *new_nodes;
  gint old_size;
  gint i;

  old_size = hash_table->size;
  g_hash_table_set_shift_from_size (hash_table, hash_table->nnodes * 2);

  new_nodes = g_new0 (GHashNode, hash_table->size);

  for (i = 0; i < old_size; i++)
    {
      GHashNode *node = &hash_table->nodes [i];
      GHashNode *new_node;
      guint hash_val;
      guint step = 0;

      if (node->key_hash <= 1)
        continue;

      hash_val = node->key_hash % hash_table->mod;
      new_node = &new_nodes [hash_val];

      while (new_node->key_hash)
        {
          step++;
          hash_val += step;
          hash_val &= hash_table->mask; new_node = &new_nodes [hash_val];
        }

      *new_node = *node;
    }

  g_free (hash_table->nodes);
  hash_table->nodes = new_nodes;
  hash_table->noccupied = hash_table->nnodes;
}

/*
 * g_hash_table_maybe_resize:
 * @hash_table: our #GHashTable
 *
 * Resizes the hash table, if needed.
 *
 * Essentially, calls g_hash_table_resize() if the table has strayed
 * too far from its ideal size for its number of nodes.
 */
static inline void g_hash_table_maybe_resize (GHashTable *hash_table)
{
  gint noccupied = hash_table->noccupied;
  gint size = hash_table->size;

  if ((size > hash_table->nnodes * 4 && size > 1 << HASH_TABLE_MIN_SHIFT) ||
      (size <= noccupied + (noccupied / 16)))
    g_hash_table_resize (hash_table);
}

/*
 * g_hash_table_insert_internal:
 * @hash_table: our #GHashTable
 * @key: the key to insert
 * @value: the value to insert
 * @keep_new_key: if %TRUE and this key already exists in the table
 *   then call the destroy notify function on the old key.  If %FALSE
 *   then call the destroy notify function on the new key.
 *
 * Implements the common logic for the g_hash_table_insert() and
 * g_hash_table_replace() functions.
 *
 * Do a lookup of @key.  If it is found, replace it with the new
 * @value (and perhaps the new @key).  If it is not found, create a
 * new node.
 */
static void g_hash_table_insert_internal (GHashTable *hash_table,
                              gpointer    key,
                              gpointer    value,
                              gboolean    keep_new_key)
{
  GHashNode *node;
  guint node_index;
  guint key_hash;
  guint old_hash;

  if (hash_table == NULL) return;
  if (hash_table->ref_count == 0) return;

  node_index = g_hash_table_lookup_node_for_insertion (hash_table, key, &key_hash);
  node = &hash_table->nodes [node_index];

  old_hash = node->key_hash;

  if (old_hash > 1)
    {
      if (keep_new_key)
        {
          if (hash_table->key_destroy_func)
            hash_table->key_destroy_func (node->key);
          node->key = key;
        }
      else
        {
          if (hash_table->key_destroy_func)
            hash_table->key_destroy_func (key);
        }

      if (hash_table->value_destroy_func)
        hash_table->value_destroy_func (node->value);

      node->value = value;
    }
  else
    {
      node->key = key;
      node->value = value;
      node->key_hash = key_hash;

      hash_table->nnodes++;

      if (old_hash == 0)
        {
          /* We replaced an empty node, and not a tombstone */
          hash_table->noccupied++;
          g_hash_table_maybe_resize (hash_table);
        }
    }
}

/**
 * g_hash_table_insert:
 * @hash_table: a #GHashTable.
 * @key: a key to insert.
 * @value: the value to associate with the key.
 *
 * Inserts a new key and value into a #GHashTable.
 *
 * If the key already exists in the #GHashTable its current value is replaced
 * with the new value. If you supplied a @value_destroy_func when creating the
 * #GHashTable, the old value is freed using that function. If you supplied
 * a @key_destroy_func when creating the #GHashTable, the passed key is freed
 * using that function.
 **/
void g_hash_table_insert (GHashTable *hash_table,
                     gpointer    key,
                     gpointer    value)
{
  g_hash_table_insert_internal (hash_table, key, value, FALSE);
}

/*
 * g_hash_table_lookup_node:
 * @hash_table: our #GHashTable
 * @key: the key to lookup against
 * @hash_return: optional key hash return location
 * Return value: index of the described #GHashNode
 *
 * Performs a lookup in the hash table.  Virtually all hash operations
 * will use this function internally.
 *
 * This function first computes the hash value of the key using the
 * user's hash function.
 *
 * If an entry in the table matching @key is found then this function
 * returns the index of that entry in the table, and if not, the
 * index of an empty node (never a tombstone).
 */
static inline guint g_hash_table_lookup_node (GHashTable    *hash_table,
                          gconstpointer  key)
{
  GHashNode *node;
  guint node_index;
  guint hash_value;
  guint step = 0;

  /* Empty buckets have hash_value set to 0, and for tombstones, it's 1.
   * We need to make sure our hash value is not one of these. */

  hash_value = (* hash_table->hash_func) (key);
  if (hash_value <= 1)
    hash_value = 2;

  node_index = hash_value % hash_table->mod;
  node = &hash_table->nodes [node_index];

  while (node->key_hash)
    {
      /*  We first check if our full hash values
       *  are equal so we can avoid calling the full-blown
       *  key equality function in most cases.
       */

      if (node->key_hash == hash_value)
        {
          if (hash_table->key_equal_func)
            {
              if (hash_table->key_equal_func (node->key, key))
                break;
            }
          else if (node->key == key)
            {
              break;
            }
        }

      step++;
      node_index += step;
      node_index &= hash_table->mask;
      node = &hash_table->nodes [node_index];
    }

  return node_index;
}

/**
 * g_hash_table_lookup:
 * @hash_table: a #GHashTable.
 * @key: the key to look up.
 *
 * Looks up a key in a #GHashTable. Note that this function cannot
 * distinguish between a key that is not present and one which is present
 * and has the value %NULL. If you need this distinction, use
 * g_hash_table_lookup_extended().
 *
 * Return value: the associated value, or %NULL if the key is not found.
 **/
gpointer g_hash_table_lookup (GHashTable   *hash_table,
                     gconstpointer key)
{
  GHashNode *node;
  guint      node_index;

  if (hash_table == NULL) return NULL;

  node_index = g_hash_table_lookup_node (hash_table, key);
  node = &hash_table->nodes [node_index];

  return node->key_hash ? node->value : NULL;
}

/**
 * g_hash_table_new:
 * @hash_func: a function to create a hash value from a key.
 *   Hash values are used to determine where keys are stored within the
 *   #GHashTable data structure. The g_direct_hash(), g_int_hash(),
 *   g_int64_hash(), g_double_hash() and g_str_hash() functions are provided
 *   for some common types of keys.
 *   If hash_func is %NULL, g_direct_hash() is used.
 * @key_equal_func: a function to check two keys for equality.  This is
 *   used when looking up keys in the #GHashTable.  The g_direct_equal(),
 *   g_int_equal(), g_int64_equal(), g_double_equal() and g_str_equal()
 *   functions are provided for the most common types of keys.
 *   If @key_equal_func is %NULL, keys are compared directly in a similar
 *   fashion to g_direct_equal(), but without the overhead of a function call.
 *
 * Creates a new #GHashTable with a reference count of 1.
 *
 * Return value: a new #GHashTable.
 **/
GHashTable *g_hash_table_new(GHashFunc hash_func, GEqualFunc key_equal_func)
{
   return g_hash_table_new_full(hash_func, key_equal_func, NULL, NULL);
}

/**
 * g_hash_table_new_full:
 * @hash_func: a function to create a hash value from a key.
 * @key_equal_func: a function to check two keys for equality.
 * @key_destroy_func: a function to free the memory allocated for the key
 *   used when removing the entry from the #GHashTable or %NULL if you
 *   don't want to supply such a function.
 * @value_destroy_func: a function to free the memory allocated for the
 *   value used when removing the entry from the #GHashTable or %NULL if
 *   you don't want to supply such a function.
 *
 * Creates a new #GHashTable like g_hash_table_new() with a reference count
 * of 1 and allows to specify functions to free the memory allocated for the
 * key and value that get called when removing the entry from the #GHashTable.
 *
 * Return value: a new #GHashTable.
 **/
GHashTable* g_hash_table_new_full (GHashFunc       hash_func,
                       GEqualFunc      key_equal_func,
                       GDestroyNotify  key_destroy_func,
                       GDestroyNotify  value_destroy_func)
{
  GHashTable *hash_table;

  hash_table = (GHashTable*)g_malloc(sizeof(GHashTable));
  //hash_table = g_slice_new (GHashTable);
  g_hash_table_set_shift (hash_table, HASH_TABLE_MIN_SHIFT);
  hash_table->nnodes             = 0;
  hash_table->noccupied          = 0;
  hash_table->hash_func          = hash_func ? hash_func : g_direct_hash;
  hash_table->key_equal_func     = key_equal_func;
  hash_table->ref_count          = 1;
  hash_table->key_destroy_func   = key_destroy_func;
  hash_table->value_destroy_func = value_destroy_func;
  hash_table->nodes              = g_new0 (GHashNode, hash_table->size);

  return hash_table;
}

/*
 * g_hash_table_remove_all_nodes:
 * @hash_table: our #GHashTable
 * @notify: %TRUE if the destroy notify handlers are to be called
 *
 * Removes all nodes from the table.  Since this may be a precursor to
 * freeing the table entirely, no resize is performed.
 *
 * If @notify is %TRUE then the destroy notify functions are called
 * for the key and value of the hash node.
 */
static void g_hash_table_remove_all_nodes (GHashTable *hash_table,
                               gboolean    notify)
{
  int i;

  for (i = 0; i < hash_table->size; i++)
    {
      GHashNode *node = &hash_table->nodes [i];

      if (node->key_hash > 1)
        {
          if (notify && hash_table->key_destroy_func)
            hash_table->key_destroy_func (node->key);

          if (notify && hash_table->value_destroy_func)
            hash_table->value_destroy_func (node->value);
        }
    }

  /* We need to set node->key_hash = 0 for all nodes - might as well be GC
   * friendly and clear everything */
  memset (hash_table->nodes, 0, hash_table->size * sizeof (GHashNode));

  hash_table->nnodes = 0;
  hash_table->noccupied = 0;
}

/**
 * g_hash_table_remove_all:
 * @hash_table: a #GHashTable
 *
 * Removes all keys and their associated values from a #GHashTable.
 *
 * If the #GHashTable was created using g_hash_table_new_full(), the keys
 * and values are freed using the supplied destroy functions, otherwise you
 * have to make sure that any dynamically allocated values are freed
 * yourself.
 *
 * Since: 2.12
 **/
void g_hash_table_remove_all (GHashTable *hash_table)
{
  if (hash_table == NULL) return;

  g_hash_table_remove_all_nodes (hash_table, TRUE);
  g_hash_table_maybe_resize (hash_table);
}

/*
 * g_hash_table_remove_node:
 * @hash_table: our #GHashTable
 * @node: pointer to node to remove
 * @notify: %TRUE if the destroy notify handlers are to be called
 *
 * Removes a node from the hash table and updates the node count.
 * The node is replaced by a tombstone. No table resize is performed.
 *
 * If @notify is %TRUE then the destroy notify functions are called
 * for the key and value of the hash node.
 */
static void g_hash_table_remove_node (GHashTable   *hash_table,
                          GHashNode    *node,
                          gboolean      notify)
{
  if (notify && hash_table->key_destroy_func)
    hash_table->key_destroy_func (node->key);

  if (notify && hash_table->value_destroy_func)
    hash_table->value_destroy_func (node->value);

  /* Erect tombstone */
  node->key_hash = 1;

  /* Be GC friendly */
  node->key = NULL;
  node->value = NULL;

  hash_table->nnodes--;
}
/*
 * g_hash_table_remove_internal:
 * @hash_table: our #GHashTable
 * @key: the key to remove
 * @notify: %TRUE if the destroy notify handlers are to be called
 * Return value: %TRUE if a node was found and removed, else %FALSE
 *
 * Implements the common logic for the g_hash_table_remove() and
 * g_hash_table_steal() functions.
 *
 * Do a lookup of @key and remove it if it is found, calling the
 * destroy notify handlers only if @notify is %TRUE.
 */
static gboolean g_hash_table_remove_internal (GHashTable *hash_table,
                gconstpointer  key,
                gboolean       notify)
{
  GHashNode *node;
  guint node_index;

  if (hash_table == NULL) return FALSE;

  node_index = g_hash_table_lookup_node (hash_table, key);
  node = &hash_table->nodes [node_index];

  /* g_hash_table_lookup_node() never returns a tombstone, so this is safe */
  if (!node->key_hash)
    return FALSE;

  g_hash_table_remove_node (hash_table, node, notify);
  g_hash_table_maybe_resize (hash_table);

  return TRUE;
}
/**
 * g_hash_table_remove:
 * @hash_table: a #GHashTable.
 * @key: the key to remove.
 *
 * Removes a key and its associated value from a #GHashTable.
 *
 * If the #GHashTable was created using g_hash_table_new_full(), the
 * key and value are freed using the supplied destroy functions, otherwise
 * you have to make sure that any dynamically allocated values are freed
 * yourself.
 *
 * Return value: %TRUE if the key was found and removed from the #GHashTable.
 **/
gboolean g_hash_table_remove (GHashTable    *hash_table,
                     gconstpointer  key)
{
  return g_hash_table_remove_internal (hash_table, key, TRUE);
}

/**
 * g_hash_table_unref:
 * @hash_table: a valid #GHashTable.
 *
 * Atomically decrements the reference count of @hash_table by one.
 * If the reference count drops to 0, all keys and values will be
 * destroyed, and all memory allocated by the hash table is released.
 * This function is MT-safe and may be called from any thread.
 *
 * Since: 2.10
 **/
void g_hash_table_unref (GHashTable *hash_table)
{
  if (hash_table == NULL) return;
  if (hash_table->ref_count == 0) return;

  hash_table->ref_count--;
  if (hash_table->ref_count == 0) {
      g_hash_table_remove_all_nodes (hash_table, TRUE);
      g_free (hash_table->nodes);
      g_free (hash_table);
  }
}

/**
 * g_hash_table_ref:
 * @hash_table: a valid #GHashTable.
 *
 * Atomically increments the reference count of @hash_table by one.
 * This function is MT-safe and may be called from any thread.
 *
 * Return value: the passed in #GHashTable.
 *
 * Since: 2.10
 **/
GHashTable *g_hash_table_ref (GHashTable *hash_table)
{
  if (hash_table == NULL) return NULL;
  if (hash_table->ref_count == 0) return hash_table;

  //g_atomic_int_add (&hash_table->ref_count, 1);
  hash_table->ref_count++;
  return hash_table;
}

guint g_hash_table_size(GHashTable *hash_table)
{
  if (hash_table == NULL) return 0;

  return hash_table->nnodes;
}

/* END of g_hash_table related functions */

/* general g_XXX substitutes */

void g_free(gpointer ptr)
{
   free(ptr);
}

gpointer g_malloc(size_t size)
{
   if (size == 0) return NULL;
   void *res = malloc(size);
   if (res == NULL) exit(1);
   return res;
}

gpointer g_malloc0(size_t size)
{
   if (size == 0) return NULL;
   void *res = calloc(size, 1);
   if (res == NULL) exit(1);
   return res;
}

gpointer g_try_malloc0(size_t size)
{
   if (size == 0) return NULL;
   return calloc(size, 1);
}

gpointer g_realloc(gpointer ptr, size_t size)
{
   if (size == 0) {
      free(ptr);
      return NULL;
   }
   void *res = realloc(ptr, size);
   if (res == NULL) exit(1);
   return res;
}

char *g_strdup(const char *str)
{
   return str ? strdup(str) : NULL;
}

char *g_strdup_printf(const char *format, ...)
{
   va_list ap;
   char *res;
   va_start(ap, format);
   res = g_strdup_vprintf(format, ap);
   va_end(ap);
   return res;
}

char *g_strdup_vprintf(const char *format, va_list ap)
{
   char *str_res = NULL;
   vasprintf(&str_res, format, ap);
   return str_res;
}

char *g_strndup(const char *str, size_t n)
{
   /* try to mimic glib's g_strndup */
   char *res = calloc(n + 1, 1);
   strncpy(res, str, n);
   return res;
}

void g_strfreev(char **str_array)
{
   char **p = str_array;
   if (p) {
      while (*p) {
         free(*p++);
      }
   }
   free(str_array);
}

gpointer g_memdup(gconstpointer mem, size_t byte_size)
{
   if (mem) {
      void *res = g_malloc(byte_size);
      memcpy(res, mem, byte_size);
      return res;
   }
   return NULL; 
}

gpointer g_new_(size_t sz, size_t n_structs)
{
   size_t need = sz * n_structs;
   if ((need / sz) != n_structs) return NULL;
   return g_malloc(need);
}

gpointer g_new0_(size_t sz, size_t n_structs)
{
   size_t need = sz * n_structs;
   if ((need / sz) != n_structs) return NULL;
   return g_malloc0(need);
}

gpointer g_renew_(size_t sz, gpointer mem, size_t n_structs)
{
   size_t need = sz * n_structs;
   if ((need / sz) != n_structs) return NULL;
   return g_realloc(mem, need);
}

/**
 * g_strconcat:
 * @string1: the first string to add, which must not be %NULL
 * @Varargs: a %NULL-terminated list of strings to append to the string
 *
 * Concatenates all of the given strings into one long string.
 * The returned string should be freed with g_free() when no longer needed.
 *
 * Note that this function is usually not the right function to use to
 * assemble a translated message from pieces, since proper translation
 * often requires the pieces to be reordered.
 *
 * <warning><para>The variable argument list <emphasis>must</emphasis> end
 * with %NULL. If you forget the %NULL, g_strconcat() will start appending
 * random memory junk to your string.</para></warning>
 *
 * Returns: a newly-allocated string containing all the string arguments
 */
gchar* g_strconcat (const gchar *string1, ...)
{
   va_list ap;
   char *res;
   size_t sz = strlen(string1);
   va_start(ap, string1);
   while (1) {
      char *arg = va_arg(ap, char*);
      if (arg == NULL) break;
      sz += strlen(arg);
   }
   va_end(ap);
   res = g_malloc(sz + 1);
   strcpy(res, string1);
   va_start(ap, string1);
   while (1) {
      char *arg = va_arg(ap, char*);
      if (arg == NULL) break;
      strcat(res, arg);
   }
   va_end(ap);
   return res;
}

/**
 * g_strsplit:
 * @string: a string to split.
 * @delimiter: a string which specifies the places at which to split the string.
 *     The delimiter is not included in any of the resulting strings, unless
 *     @max_tokens is reached.
 * @max_tokens: the maximum number of pieces to split @string into. If this is
 *              less than 1, the string is split completely.
 *
 * Splits a string into a maximum of @max_tokens pieces, using the given
 * @delimiter. If @max_tokens is reached, the remainder of @string is appended
 * to the last token.
 *
 * As a special case, the result of splitting the empty string "" is an empty
 * vector, not a vector containing a single string. The reason for this
 * special case is that being able to represent a empty vector is typically
 * more useful than consistent handling of empty elements. If you do need
 * to represent empty elements, you'll need to check for the empty string
 * before calling g_strsplit().
 *
 * Return value: a newly-allocated %NULL-terminated array of strings. Use
 *    g_strfreev() to free it.
 **/
gchar** g_strsplit (const gchar *string,
            const gchar *delimiter,
            gint         max_tokens)
{
  GSList *string_list = NULL, *slist;
  gchar **str_array, *s;
  guint n = 0;
  const gchar *remainder;

  if (string == NULL) return NULL;
  if (delimiter == NULL) return NULL;
  if (delimiter[0] == '\0') return NULL;

  if (max_tokens < 1)
    max_tokens = G_MAXINT;

  remainder = string;
  s = strstr (remainder, delimiter);
  if (s)
    {
      gsize delimiter_len = strlen (delimiter);

      while (--max_tokens && s)
        {
          gsize len;

          len = s - remainder;
          string_list = g_slist_prepend (string_list,
                                         g_strndup (remainder, len));
          n++;
          remainder = s + delimiter_len;
          s = strstr (remainder, delimiter);
        }
    }
  if (*string)
    {
      n++;
      string_list = g_slist_prepend (string_list, g_strdup (remainder));
    }

  str_array = g_new (gchar*, n + 1);

  str_array[n--] = NULL;
  for (slist = string_list; slist; slist = slist->next)
    str_array[n--] = slist->data;

  g_slist_free (string_list);

  return str_array;
}