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41 results

chacha-core-internal.c

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  • Forked from Nettle / nettle
    Source project has a limited visibility.
    mapping.c 64.96 KiB
    /*
    || This file is part of Pike. For copyright information see COPYRIGHT.
    || Pike is distributed under GPL, LGPL and MPL. See the file COPYING
    || for more information.
    || $Id: mapping.c,v 1.201 2008/05/11 14:55:53 mast Exp $
    */
    
    #include "global.h"
    #include "main.h"
    #include "object.h"
    #include "mapping.h"
    #include "svalue.h"
    #include "array.h"
    #include "pike_macros.h"
    #include "pike_error.h"
    #include "pike_memory.h"
    #include "dynamic_buffer.h"
    #include "interpret.h"
    #include "las.h"
    #include "gc.h"
    #include "stralloc.h"
    #include "pike_security.h"
    #include "block_alloc.h"
    #include "opcodes.h"
    #include "stuff.h"
    
    #define AVG_LINK_LENGTH 4
    #define MIN_LINK_LENGTH 1
    #define MAP_SLOTS(X) ((X)?((X)+((X)>>4)+8):0)
    
    struct mapping *first_mapping;
    
    struct mapping *gc_internal_mapping = 0;
    static struct mapping *gc_mark_mapping_pos = 0;
    
    #define unlink_mapping_data(M) do{				\
     struct mapping_data *md_=(M);					\
     if(md_->hardlinks) { md_->hardlinks--; md_->valrefs--; }	\
     free_mapping_data(M);						\
    }while(0)
    
    #define MAPPING_DATA_SIZE(HSIZE, KEYPAIRS) \
       PTR_TO_INT(MD_KEYPAIRS(0, HSIZE) + KEYPAIRS)
    
    #undef EXIT_BLOCK
    #define EXIT_BLOCK(m)	do{						\
    DO_IF_DEBUG(								\
      if(m->refs) {								\
        DO_IF_DMALLOC(describe_something(m, T_MAPPING, 0,2,0, NULL));	\
        Pike_fatal("really free mapping on mapping with %d refs.\n", m->refs); \
      }									\
    )									\
    									\
      FREE_PROT(m);								\
    									\
      unlink_mapping_data(m->data);						\
    									\
      DOUBLEUNLINK(first_mapping, m);					\
    									\
      GC_FREE(m);                                                           \
    }while(0)
    
    
    #undef COUNT_OTHER
    
    #define COUNT_OTHER() do{				\
      struct mapping *m;					\
      double datasize = 0.0;				\
      for(m=first_mapping;m;m=m->next)			\
      {							\
        datasize+=MAPPING_DATA_SIZE(m->data->hashsize, m->data->num_keypairs) / \
          (double) m->data->refs;						\
      }							\
      size += (INT32) datasize;				\
    }while(0)
    
    BLOCK_ALLOC_FILL_PAGES(mapping, 2)
    
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
    #define IF_ELSE_KEYPAIR_LOOP(X, Y)	Y
    #define FREE_KEYPAIR(md, k) do {	\
        k->next = md->free_list;		\
        md->free_list = k;			\
      } while(0)
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
    #define IF_ELSE_KEYPAIR_LOOP(X, Y)	X
    #define FREE_KEYPAIR(md, k) do {			\
        md->free_list--;					\
        if (k != md->free_list) {				\
          struct keypair **prev_;				\
          unsigned INT32 h_;				\
          INT32 e;						\
          /* Move the last keypair to the new hole. */	\
          *k = *(md->free_list);				\
          h_ = k->hval % md->hashsize;			\
          prev_ = md->hash + h_;				\
          DO_IF_DEBUG(					\
    	if (!*prev_) {					\
    	  Pike_fatal("Node to move not found!\n");	\
    	}						\
          );						\
          while (*prev_ != md->free_list) {			\
    	prev_ = &((*prev_)->next);			\
            DO_IF_DEBUG(					\
    	  if (!*prev_) {				\
    	    Pike_fatal("Node to move not found!\n");	\
    	  }						\
    	);						\
          }							\
          *prev_ = k;					\
        }							\
      } while(0)
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
    
    #ifdef PIKE_DEBUG
    
    /** This function checks that the type field isn't lacking any bits.
     * It is used for debugging purposes only.
     */
    static void check_mapping_type_fields(const struct mapping *m)
    {
      INT32 e;
      const struct keypair *k=0;
      const struct mapping_data *md;
      TYPE_FIELD ind_types, val_types;
    
      ind_types=val_types=0;
    
      md = m->data;
      NEW_MAPPING_LOOP(md)
        {
          val_types |= 1 << k->val.type;
          ind_types |= 1 << k->ind.type;
        }
    
      if(val_types & ~(m->data->val_types))
        Pike_fatal("Mapping value types out of order!\n");
    
      if(ind_types & ~(m->data->ind_types))
        Pike_fatal("Mapping indices types out of order!\n");
    }
    #endif
    
    static struct mapping_data empty_data =
      { PIKE_CONSTANT_MEMOBJ_INIT(1), 1, 0,0,0,0,0,0, 0,
        IF_ELSE_KEYPAIR_LOOP((struct keypair *)&empty_data.hash, 0), {0}};
    static struct mapping_data weak_ind_empty_data =
      { PIKE_CONSTANT_MEMOBJ_INIT(1), 1, 0,0,0,0,0,0, MAPPING_WEAK_INDICES,
        IF_ELSE_KEYPAIR_LOOP((struct keypair *)&weak_ind_empty_data.hash, 0), {0}};
    static struct mapping_data weak_val_empty_data =
      { PIKE_CONSTANT_MEMOBJ_INIT(1), 1, 0,0,0,0,0,0, MAPPING_WEAK_VALUES,
        IF_ELSE_KEYPAIR_LOOP((struct keypair *)&weak_val_empty_data.hash, 0), {0}};
    static struct mapping_data weak_both_empty_data =
      { PIKE_CONSTANT_MEMOBJ_INIT(1), 1, 0,0,0,0,0,0, MAPPING_WEAK,
        IF_ELSE_KEYPAIR_LOOP((struct keypair *)&weak_both_empty_data.hash, 0), {0}};
    
    /** This function allocates the hash table and svalue space for a mapping
     * struct. The size is the max number of indices that can fit in the
     * allocated space.
     */
    static void init_mapping(struct mapping *m,
    			 INT32 size,
    			 INT16 flags)
    {
      struct mapping_data *md;
      ptrdiff_t e;
      INT32 hashsize;
    
      debug_malloc_touch(m);
    #ifdef PIKE_DEBUG
      if (Pike_in_gc > GC_PASS_PREPARE && Pike_in_gc < GC_PASS_ZAP_WEAK)
        Pike_fatal("Can't allocate a new mapping_data inside gc.\n");
      if(size < 0) Pike_fatal("init_mapping with negative value.\n");
    #endif
      if(size)
      {
        hashsize=find_good_hash_size(size / AVG_LINK_LENGTH + 1);
    
        e=MAPPING_DATA_SIZE(hashsize, size);
    
        md=(struct mapping_data *)xalloc(e);
    
        m->data=md;
        md->hashsize=hashsize;
        
        MEMSET((char *)md->hash, 0, sizeof(struct keypair *) * md->hashsize);
        
        md->free_list=MD_KEYPAIRS(md, hashsize);
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
        for(e=1;e<size;e++)
        {
          md->free_list[e-1].next = md->free_list + e;
          mark_free_svalue (&md->free_list[e-1].ind);
          mark_free_svalue (&md->free_list[e-1].val);
        }
        md->free_list[e-1].next=0;
        mark_free_svalue (&md->free_list[e-1].ind);
        mark_free_svalue (&md->free_list[e-1].val);
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
        md->ind_types = 0;
        md->val_types = 0;
        md->flags = flags;
        md->size = 0;
        md->refs=0;
        md->valrefs=0;
        md->hardlinks=0;
        md->num_keypairs=size;
      }else{
        switch (flags & MAPPING_WEAK) {
          case 0: md = &empty_data; break;
          case MAPPING_WEAK_INDICES: md = &weak_ind_empty_data; break;
          case MAPPING_WEAK_VALUES: md = &weak_val_empty_data; break;
          default: md = &weak_both_empty_data; break;
        }
      }
      add_ref(md);
      m->data=md;
    #ifdef MAPPING_SIZE_DEBUG
      m->debug_size = md->size;
    #endif
    }
    
    /** This function allocates an empty mapping with initial room
     * for 'size' values.
     *
     * @param size initial number of values
     * @return the newly allocated mapping
     * @see do_free_mapping
     * @see free_mapping
     */
    PMOD_EXPORT struct mapping *debug_allocate_mapping(int size)
    {
      struct mapping *m;
    
      m=alloc_mapping();
    
      GC_ALLOC(m);
    
      INITIALIZE_PROT(m);
      init_mapping(m,size,0);
    
      m->refs = 0;
      add_ref(m);	/* For DMALLOC... */
    
      DOUBLELINK(first_mapping, m);
    
      return m;
    }
    
    
    PMOD_EXPORT void really_free_mapping_data(struct mapping_data *md)
    {
      INT32 e;
      struct keypair *k;
      debug_malloc_touch(md);
    
    #ifdef PIKE_DEBUG
      if (md->refs) {
        Pike_fatal("really_free_mapping_data(): md has non-zero refs: %d\n",
    	  md->refs);
      }
    #endif /* PIKE_DEBUG */
    
      NEW_MAPPING_LOOP(md)
      {
        free_svalue(& k->val);
        free_svalue(& k->ind);
      }
    
      free((char *) md);
      GC_FREE_BLOCK(md);
    }
    
    PMOD_EXPORT void do_free_mapping(struct mapping *m)
    {
      if (m)
        inl_free_mapping(m);
    }
    
    /* This function is used to rehash a mapping without losing the internal
     * order in each hash chain. This is to prevent mappings from becoming
     * inefficient just after being rehashed.
     */
    static void mapping_rehash_backwards_evil(struct mapping_data *md,
    					  struct keypair *from)
    {
      unsigned INT32 h;
      struct keypair *k, *prev = NULL, *next;
    
      if(!(k = from)) return;
    
      /* Reverse the hash chain. */
      while ((next = k->next)) {
        k->next = prev;
        prev = k;
        k = next;
      }
      k->next = prev;
    
      from = k;
    
      /* Rehash and reverse the hash chain. */
      while (from) {
        /* unlink */
        k=md->free_list;
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
    #ifdef PIKE_DEBUG
        if(!k) Pike_fatal("Error in rehash: not enough keypairs.\n");
    #endif
        md->free_list=k->next;
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
        md->free_list++;
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
    
        /* initialize */
        *k=*from;
    
        /* link */
        h=k->hval;
        h%=md->hashsize;
        k->next=md->hash[h];
        md->hash[h]=k;
    
        /* update */
        md->ind_types |= 1<< (k->ind.type);
        md->val_types |= 1<< (k->val.type);
        md->size++;
    
        /* Reverse */
        prev = from->next;
        from->next = next;
        next = from;
        from = prev;
      }
    }
    
    static void mapping_rehash_backwards_good(struct mapping_data *md,
    					  struct keypair *from)
    {
      unsigned INT32 h;
      struct keypair *k, *prev = NULL, *next;
    
      if(!(k = from)) return;
    
      /* Reverse the hash chain. */
      while ((next = k->next)) {
        k->next = prev;
        prev = k;
        k = next;
      }
      k->next = prev;
    
      from = k;
    
      /* Rehash and reverse the hash chain. */
      while (from) {
        /* unlink */
        k=md->free_list;
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
    #ifdef PIKE_DEBUG
        if(!k) Pike_fatal("Error in rehash: not enough keypairs.\n");
    #endif
        md->free_list=k->next;
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
        md->free_list++;
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
    
        /* initialize */
        k->hval=from->hval;
        assign_svalue_no_free(&k->ind, &from->ind);
        assign_svalue_no_free(&k->val, &from->val);
    
        /* link */
        h=k->hval;
        h%=md->hashsize;
        k->next=md->hash[h];
        md->hash[h]=k;
    
        /* update */
        md->ind_types |= 1<< (k->ind.type);
        md->val_types |= 1<< (k->val.type);
        md->size++;
    
        /* Reverse */
        prev = from->next;
        from->next = next;
        next = from;
        from = prev;
      }
    }
    
    /** This function re-allocates a mapping. It adjusts the max no. of
     * values can be fitted into the mapping. It takes a bit of time to
     * run, but is used seldom enough not to degrade preformance significantly.
     *
     * @param m the mapping to be rehashed
     * @param new_size new mappingsize
     * @return the rehashed mapping
     */
    static struct mapping *rehash(struct mapping *m, int new_size)
    {
      struct mapping_data *md, *new_md;
    #ifdef PIKE_DEBUG
      INT32 tmp=m->data->size;
    #endif
      INT32 e;
    
      md=m->data;
      debug_malloc_touch(md);
    #ifdef PIKE_DEBUG
      if(md->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    
      if(d_flag>1)  check_mapping(m);
    #endif
    
      init_mapping(m, new_size, md->flags);
      debug_malloc_touch(m);
      new_md=m->data;
    
      /* This operation is now 100% atomic - no locking required */
      if(md->refs>1)
      {
        /* good */
        for(e=0;e<md->hashsize;e++)
          mapping_rehash_backwards_good(new_md, md->hash[e]);
    
        unlink_mapping_data(md);
      }else{
        /* evil */
        for(e=0;e<md->hashsize;e++)
          mapping_rehash_backwards_evil(new_md, md->hash[e]);
    
        free((char *)md);
        GC_FREE_BLOCK(md);
      }
    
    #ifdef PIKE_DEBUG
      if(m->data->size != tmp)
        Pike_fatal("Rehash failed, size not same any more.\n");
    #endif
    #ifdef MAPPING_SIZE_DEBUG
      m->debug_size = m->data->size;
    #endif
    
    #ifdef PIKE_DEBUG
      if(d_flag>1)  check_mapping(m);
    #endif
    
      return m;
    }
    
    /*
     * No need for super efficiency, should not be called very often
     * -Hubbe
     */
    #define LOW_RELOC(X) X= (void *) ((char *)(X) + off);
    #define RELOC(X) if(X) LOW_RELOC(X)
    
    struct mapping_data *copy_mapping_data(struct mapping_data *md)
    {
      long e;
      ptrdiff_t size, off;
      struct mapping_data *nmd;
      struct keypair *keypairs;
    
    #ifdef PIKE_DEBUG
      if (Pike_in_gc > GC_PASS_PREPARE && Pike_in_gc < GC_PASS_ZAP_WEAK)
        Pike_fatal("Can't allocate a new mapping_data inside gc.\n");
    #endif
    
      debug_malloc_touch(md);
    
      size=MAPPING_DATA_SIZE(md->hashsize, md->num_keypairs);
    
      nmd=(struct mapping_data *)xalloc(size);
      MEMCPY(nmd, md, size);
      off=((char *)nmd) - ((char *)md);
    
      RELOC(nmd->free_list);
      for(e=0;e<nmd->hashsize;e++) RELOC(nmd->hash[e]);
    
      keypairs=MD_KEYPAIRS(nmd, nmd->hashsize);
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
      for(e=0;e<nmd->num_keypairs;e++)
      {
        RELOC(keypairs[e].next);
        add_ref_svalue(& keypairs[e].ind);
        add_ref_svalue(& keypairs[e].val);
      }
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
      for(e=0;e<nmd->size;e++)
      {
        RELOC(keypairs[e].next);
        add_ref_svalue(& keypairs[e].ind);
        add_ref_svalue(& keypairs[e].val);
      }
    #endif /* PIKE_MAPPING_KEYPAIR_LOOP */
    
      nmd->refs=0;
      add_ref(nmd);	/* For DMALLOC... */
      nmd->valrefs=0;
      nmd->hardlinks=0;
    
      if(md->hardlinks)
      {
    #ifdef PIKE_DEBUG
        if(md->refs <= 0 || md->valrefs<=0)
          Pike_fatal("Hardlink without refs/valrefs!\n");
    #endif
        md->hardlinks--;
        md->valrefs--;
      }
      sub_ref(md);
    
      return nmd;
    }
    
    #define MAPPING_DATA_IN_USE(MD) ((MD)->refs != (MD)->hardlinks + 1)
    
    #define LOW_FIND(FUN, KEY, FOUND, NOT_FOUND) do {		\
      md=m->data;                                                   \
      add_ref(md);						        \
      if(md->hashsize)						\
      {								\
        h=h2 % md->hashsize;					\
        DO_IF_DEBUG( if(d_flag > 1) check_mapping_type_fields(m); ) \
        if(md->ind_types & ((1 << key->type) | BIT_OBJECT))		\
        {								\
          for(prev= md->hash + h;(k=*prev);prev=&k->next)		\
          {								\
    	if(h2 == k->hval && FUN(& k->ind, KEY))		        \
    	{							\
    	  FOUND;						\
    	}							\
          }								\
        }								\
      }								\
      NOT_FOUND;                                                    \
    }while(0)
    
    
    #define LOW_FIND2(FUN, KEY, FOUND, NOT_FOUND) do {		\
      struct keypair *k2;						\
      md=m->data;							\
      add_ref(md);							\
      if(md->hashsize)						\
      {								\
        h=h2 % md->hashsize;					\
        DO_IF_DEBUG( if(d_flag > 1) check_mapping_type_fields(m); ) \
        if(md->ind_types & ((1 << key->type) | BIT_OBJECT))		\
        {								\
          k2=omd->hash[h2 % omd->hashsize];			        \
          prev= md->hash + h;					\
          for(;(k=*prev) && k2;(prev=&k->next),(k2=k2->next))	\
            if(!(h2 == k->hval && is_identical(&k2->ind, &k->ind)))	\
               break;						\
          for(;(k=*prev);prev=&k->next)				\
          {								\
    	if(FUN(& k->ind, KEY))					\
    	{							\
    	  FOUND;						\
    	}							\
          }								\
        }								\
      }								\
      NOT_FOUND;							\
    }while(0)
    
    
    #define SAME_DATA(SAME,NOT_SAME) 	\
      if(m->data == md)				\
      {						\
        SAME;					\
      }else{ 					\
        NOT_SAME;					\
      }
    
    
    /* FIXME: the 'no action' might need to be fixed.... */
    #define FIND() do{						\
      LOW_FIND(is_eq, key,						\
    	   omd=md;						\
    	   SAME_DATA( break,					\
    		     struct svalue *tmp=&k->ind;		\
    		     LOW_FIND(is_identical, tmp, break, ;);	\
    		     free_mapping_data(omd)),			\
    	   break);				                \
        free_mapping_data(md);					\
    }while(0)
    
          
    /* Assumes md is *NOT* locked */
    #define COPYMAP2() do {				\
      ptrdiff_t off;				\
      m->data=copy_mapping_data(m->data);		\
      debug_malloc_touch(m->data);                  \
      DO_IF_DEBUG( if(d_flag>1)  check_mapping(m); ) \
      off=((char *)m->data)-((char *)md);		\
      LOW_RELOC(k);					\
      LOW_RELOC(prev);				\
      md=m->data;                                   \
    }while(0)
    
    #define PREPARE_FOR_DATA_CHANGE2() \
     if(md->valrefs) COPYMAP2()
    
    #define PREPARE_FOR_INDEX_CHANGE2() \
      if(md->refs>1) COPYMAP2()
    
    #define PROPAGATE() do {			\
       if(md->refs==1)				\
       {						\
         h=h2 % md->hashsize;                       \
         *prev=k->next;				\
         k->next=md->hash[h];			\
         md->hash[h]=k;				\
       }						\
     }while(0)
    
    
    /* Assumes md is locked */
    #define COPYMAP() do {			        \
      ptrdiff_t off;				\
      m->data=copy_mapping_data(m->data);		\
      debug_malloc_touch(m->data);                  \
      off=((char *)m->data)-((char *)md);		\
      LOW_RELOC(k);					\
      free_mapping_data(md);                        \
      md=m->data;                                   \
      add_ref(md);                                   \
    }while(0)
    
    #define PREPARE_FOR_DATA_CHANGE() \
     if(md->valrefs) COPYMAP()
    
    #define PREPARE_FOR_INDEX_CHANGE() \
     if(md->refs>1) COPYMAP()
    
    /** This function brings the type fields in the mapping up to speed.
     * It should be used only when the type fields MUST be correct, which is not
     * very often.
     */
    PMOD_EXPORT void mapping_fix_type_field(struct mapping *m)
    {
      INT32 e;
      struct keypair *k;
      TYPE_FIELD ind_types, val_types;
    
      val_types = ind_types = 0;
    
      NEW_MAPPING_LOOP(m->data)
        {
          val_types |= 1 << k->val.type;
          ind_types |= 1 << k->ind.type;
        }
    
    #ifdef PIKE_DEBUG
      if(val_types & ~(m->data->val_types))
        Pike_fatal("Mapping value types out of order!\n");
    
      if(ind_types & ~(m->data->ind_types))
        Pike_fatal("Mapping indices types out of order!\n");
    #endif
      m->data->val_types = val_types;
      m->data->ind_types = ind_types;
    }
    
    PMOD_EXPORT void mapping_set_flags(struct mapping *m, int flags)
    {
      struct mapping_data *md = m->data;
    
      if ((md->flags != flags) && (md->refs > 1)) {
        struct keypair *k = NULL, *prev = NULL;
        COPYMAP2();
        md = m->data;
      }
    #ifdef PIKE_DEBUG
      if(flags & MAPPING_WEAK)
      {
        debug_malloc_touch(m);
        debug_malloc_touch(md);
      }
      else
      {
        debug_malloc_touch(m);
        debug_malloc_touch(md);
      }
    #endif
      md->flags = flags;
    }
    
    PMOD_EXPORT void low_mapping_insert(struct mapping *m,
    				    const struct svalue *key,
    				    const struct svalue *val,
    				    int overwrite)
    {
      unsigned INT32 h,h2;
      struct keypair *k, **prev;
      struct mapping_data *md, *omd;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      h2=hash_svalue(key);
      
    #ifdef PIKE_DEBUG
      if(d_flag>1)  check_mapping(m);
    #endif
    
      LOW_FIND(is_eq, key,
    	   struct svalue *tmp=&k->ind;
    	   SAME_DATA(goto mi_set_value,
    		     omd=md;
    		     LOW_FIND(is_identical, tmp,
    			      free_mapping_data(omd);
    			      goto mi_set_value,
    			      free_mapping_data(omd);
    			      goto mi_do_nothing)),
    	   Z:
    	   SAME_DATA(goto mi_insert,
    		     omd=md;
    		     LOW_FIND2(is_eq, key,
    			       free_mapping_data(omd);
    			       goto mi_do_nothing,
    			       free_mapping_data(omd);
    			       goto Z)));
    
     mi_do_nothing:
      free_mapping_data(md);
      return;
    
     mi_set_value:
    #ifdef PIKE_DEBUG
      if(m->data != md)
        Pike_fatal("Wrong dataset in mapping_insert!\n");
      if(d_flag>1)  check_mapping(m);
    #endif
      free_mapping_data(md);
      if(!overwrite) return;
      PREPARE_FOR_DATA_CHANGE2();
      PROPAGATE(); /* propagate after preparing */
      md->val_types |= 1 << val->type;
      if (overwrite == 2 && key->type == T_OBJECT)
        /* Should replace the index too. It's only for objects that it's
         * possible to tell the difference. */
        assign_svalue (&k->ind, key);
      assign_svalue(& k->val, val);
    #ifdef PIKE_DEBUG
      if(d_flag>1)  check_mapping(m);
    #endif
      return;
    
     mi_insert:
    #ifdef PIKE_DEBUG
      if(m->data != md)
        Pike_fatal("Wrong dataset in mapping_insert!\n");
      if(d_flag>1)  check_mapping(m);
    #endif
      free_mapping_data(md);
      /* We do a re-hash here instead of copying the mapping. */
      if(
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
         (!md->free_list) ||
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
         (md->size >= md->num_keypairs) ||
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
         md->refs>1)
      {
        debug_malloc_touch(m);
        rehash(m, md->size * 2 + 2);
        md=m->data;
      }
      h=h2 % md->hashsize;
    
      /* no need to lock here since we are not calling is_eq - Hubbe */
    
      k=md->free_list;
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
      md->free_list=k->next;
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
      md->free_list++;
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
      k->next=md->hash[h];
      md->hash[h]=k;
      md->ind_types |= 1 << key->type;
      md->val_types |= 1 << val->type;
      assign_svalue_no_free(& k->ind, key);
      assign_svalue_no_free(& k->val, val);
      k->hval = h2;
      md->size++;
    #ifdef MAPPING_SIZE_DEBUG
      if(m->data ==md)
        m->debug_size++;
    #endif
    
    #ifdef PIKE_DEBUG
      if(d_flag>1)  check_mapping(m);
    #endif
    }
    
    PMOD_EXPORT void mapping_insert(struct mapping *m,
    				const struct svalue *key,
    				const struct svalue *val)
    {
      low_mapping_insert(m,key,val,1);
    }
    
    /* Inline the above in this file. */
    #define mapping_insert(M, KEY, VAL) low_mapping_insert ((M), (KEY), (VAL), 1)
    
    PMOD_EXPORT union anything *mapping_get_item_ptr(struct mapping *m,
    				     const struct svalue *key,
    				     TYPE_T t)
    {
      unsigned INT32 h, h2;
      struct keypair *k, **prev;
      struct mapping_data *md,*omd;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    
      if(d_flag>1)  check_mapping(m);
    
      debug_malloc_touch(m);
      debug_malloc_touch(m->data);
    #endif
    
      h2=hash_svalue(key);
    
      LOW_FIND(is_eq, key,
    	   struct svalue *tmp=&k->ind;
    	   SAME_DATA(goto mg_set_value,
    		     omd=md;
    		     LOW_FIND(is_identical, tmp,
    			      free_mapping_data(omd);
    			      goto mg_set_value,
    			      free_mapping_data(omd);
    			      goto mg_do_nothing)),
    	   Z:
    	   SAME_DATA(goto mg_insert,
    		     omd=md;
    		     LOW_FIND2(is_eq, key,
    			       free_mapping_data(omd);
    			       goto mg_do_nothing,
    			       free_mapping_data(omd);
    			       goto Z)));
    
    
    
     mg_do_nothing:
      free_mapping_data(md);
      return 0;
    
     mg_set_value:
    #ifdef PIKE_DEBUG
      if(m->data != md)
        Pike_fatal("Wrong dataset in mapping_get_item_ptr!\n");
      if(d_flag)
        check_mapping(m);
    #endif
      free_mapping_data(md);
      if(k->val.type == t)
      {
        PREPARE_FOR_DATA_CHANGE2();
        PROPAGATE(); /* prepare then propagate */
        
        return & ( k->val.u );
      }
      
      return 0;
      
     mg_insert:
    #ifdef PIKE_DEBUG
      if(m->data != md)
        Pike_fatal("Wrong dataset in mapping_get_item_ptr!\n");
      if(d_flag)
        check_mapping(m);
    #endif
      free_mapping_data(md);
    
      if(t != T_INT) return 0;
    
      /* no need to call PREPARE_* because we re-hash instead */
      if(
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
         !(md->free_list) ||
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
         (md->size >= md->num_keypairs) ||
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
         md->refs>1)
      {
        debug_malloc_touch(m);
        rehash(m, md->size * 2 + 2);
        md=m->data;
      }
      h=h2 % md->hashsize;
    
      k=md->free_list;
    #ifndef PIKE_MAPPING_KEYPAIR_LOOP
      md->free_list=k->next;
    #else /* PIKE_MAPPING_KEYPAIR_LOOP */
      md->free_list++;
    #endif /* !PIKE_MAPPING_KEYPAIR_LOOP */
      k->next=md->hash[h];
      md->hash[h]=k;
      assign_svalue_no_free(& k->ind, key);
      k->val.type=T_INT;
      k->val.subtype=NUMBER_NUMBER;
      k->val.u.integer=0;
      k->hval = h2;
      md->ind_types |= 1 << key->type;
      md->val_types |= BIT_INT;
      md->size++;
    #ifdef MAPPING_SIZE_DEBUG
      if(m->data ==md)
        m->debug_size++;
    #endif
    
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
    
      return & ( k->val.u );
    }
    
    PMOD_EXPORT void map_delete_no_free(struct mapping *m,
    			const struct svalue *key,
    			struct svalue *to)
    {
      unsigned INT32 h,h2;
      struct keypair *k, **prev;
      struct mapping_data *md,*omd;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
      if(d_flag>1)  check_mapping(m);
      debug_malloc_touch(m);
    #endif
    
      h2=hash_svalue(key);
    
      LOW_FIND(is_eq, key,
    	   struct svalue *tmp=&k->ind;
    	   SAME_DATA(goto md_remove_value,
    		     omd=md;
    		     LOW_FIND(is_identical, tmp,
    			      free_mapping_data(omd);
    			      goto md_remove_value,
    			      free_mapping_data(omd);
    			      goto md_do_nothing)),
    	   goto md_do_nothing);
    
     md_do_nothing:
      debug_malloc_touch(m);
      free_mapping_data(md);
      if(to)
      {
        to->type=T_INT;
        to->subtype=NUMBER_UNDEFINED;
        to->u.integer=0;
      }
      return;
    
     md_remove_value:
    #ifdef PIKE_DEBUG
      if(md->refs <= 1)
        Pike_fatal("Too few refs i mapping->data\n");
      if(m->data != md)
        Pike_fatal("Wrong dataset in mapping_delete!\n");
      if(d_flag>1)  check_mapping(m);
      debug_malloc_touch(m);
    #endif
      free_mapping_data(md);
      PREPARE_FOR_INDEX_CHANGE2();
      /* No need to propagate */
      *prev=k->next;
      free_svalue(& k->ind);
      if(to)
        move_svalue (to, &k->val);
      else
        free_svalue(& k->val);
    
      FREE_KEYPAIR(md, k);
    
      mark_free_svalue (&md->free_list->ind);
      mark_free_svalue (&md->free_list->val);
    
      md->size--;
    #ifdef MAPPING_SIZE_DEBUG
      if(m->data ==md)
        m->debug_size--;
    #endif
      
      if(md->size < (md->hashsize + 1) * MIN_LINK_LENGTH)
      {
        debug_malloc_touch(m);
        rehash(m, MAP_SLOTS(m->data->size));
      }
      
    #ifdef PIKE_DEBUG
      if(d_flag>1)  check_mapping(m);
    #endif
      return;
    }
    
    PMOD_EXPORT void check_mapping_for_destruct(struct mapping *m)
    {
      INT32 e;
      struct keypair *k, **prev;
      TYPE_FIELD ind_types, val_types;
      struct mapping_data *md=m->data;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
      if(d_flag>1)  check_mapping(m);
      debug_malloc_touch(m);
      if (Pike_in_gc > GC_PASS_PREPARE && Pike_in_gc < GC_PASS_FREE)
        Pike_fatal("check_mapping_for_destruct called in invalid pass inside gc.\n");
    #endif
    
      /* no is_eq -> no locking */
    
      if(!md->size) return;
    
      if((md->ind_types | md->val_types) & (BIT_OBJECT | BIT_FUNCTION))
      {
        val_types = ind_types = 0;
        md->val_types |= BIT_INT;
        for(e=0;e<md->hashsize;e++)
        {
          for(prev= md->hash + e;(k=*prev);)
          {
    	check_destructed(& k->val);
    	
    	if((k->ind.type == T_OBJECT || k->ind.type == T_FUNCTION) &&
    	   !k->ind.u.object->prog)
    	{
    	  debug_malloc_touch(m);
    	  debug_malloc_touch(md);
    	  PREPARE_FOR_INDEX_CHANGE2();
    	  *prev=k->next;
    	  free_svalue(& k->ind);
    	  free_svalue(& k->val);
    	  FREE_KEYPAIR(md, k);
    	  mark_free_svalue (&md->free_list->ind);
    	  mark_free_svalue (&md->free_list->val);
    	  md->size--;
    #ifdef MAPPING_SIZE_DEBUG
    	  if(m->data ==md)
    	  {
    	    m->debug_size++;
    	    debug_malloc_touch(m);
    	  }
    #endif
    	  debug_malloc_touch(md);
    	}else{
    	  val_types |= 1 << k->val.type;
    	  ind_types |= 1 << k->ind.type;
    	  prev=&k->next;
    	}
          }
        }
    
        md->val_types = val_types;
        md->ind_types = ind_types;
    
        if(MAP_SLOTS(md->size) < md->hashsize * MIN_LINK_LENGTH)
        {
          debug_malloc_touch(m);
          rehash(m, MAP_SLOTS(md->size));
        }
    
    #ifdef PIKE_DEBUG
        if(d_flag>1)  check_mapping(m);
    #endif
      }
    }
    
    PMOD_EXPORT struct svalue *low_mapping_lookup(struct mapping *m,
    					      const struct svalue *key)
    {
      unsigned INT32 h,h2;
      struct keypair *k=0, **prev=0;
      struct mapping_data *md, *omd;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
      if(d_flag>1)  check_mapping(m);
    #endif
    
      h2=hash_svalue(key);
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
      FIND();
      if(k)
      {
        PROPAGATE();
        return &k->val;
      }
      return 0;
    }
    
    PMOD_EXPORT struct svalue *low_mapping_string_lookup(struct mapping *m,
                                                         struct pike_string *p)
    {
      struct svalue tmp;
      tmp.type=T_STRING;
      tmp.u.string=p;
      return low_mapping_lookup(m, &tmp);
    }
    
    PMOD_EXPORT void mapping_string_insert(struct mapping *m,
                                           struct pike_string *p,
                                           const struct svalue *val)
    {
      struct svalue tmp;
      tmp.type=T_STRING;
      tmp.u.string=p;
      mapping_insert(m, &tmp, val);
    }
    
    PMOD_EXPORT void mapping_string_insert_string(struct mapping *m,
    				  struct pike_string *p,
    				  struct pike_string *val)
    {
      struct svalue tmp;
      tmp.type=T_STRING;
      tmp.u.string=val;
      mapping_string_insert(m, p, &tmp);
    }
    
    PMOD_EXPORT struct svalue *simple_mapping_string_lookup(struct mapping *m,
    							const char *p)
    {
      struct pike_string *tmp;
      if((tmp=findstring(p)))
        return low_mapping_string_lookup(m,tmp);
      return 0;
    }
    
    /* Lookup in a mapping of mappings */
    PMOD_EXPORT struct svalue *mapping_mapping_lookup(struct mapping *m,
    						  const struct svalue *key1,
    						  const struct svalue *key2,
    						  int create)
    {
      struct svalue tmp;
      struct mapping *m2;
      struct svalue *s=low_mapping_lookup(m, key1);
      debug_malloc_touch(m);
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      if(!s || !s->type==T_MAPPING)
      {
        if(!create) return 0;
        tmp.u.mapping=allocate_mapping(5);
        tmp.type=T_MAPPING;
        mapping_insert(m, key1, &tmp);
        debug_malloc_touch(m);
        debug_malloc_touch(tmp.u.mapping);
        free_mapping(tmp.u.mapping); /* There is one ref in 'm' */
        s=&tmp;
      }
    
      m2=s->u.mapping;
      debug_malloc_touch(m2);
      s=low_mapping_lookup(m2, key2);
      if(s) return s;
      if(!create) return 0;
    
      tmp.type=T_INT;
      tmp.subtype=NUMBER_UNDEFINED;
      tmp.u.integer=0;
    
      mapping_insert(m2, key2, &tmp);
      debug_malloc_touch(m2);
    
      return low_mapping_lookup(m2, key2);
    }
    
    
    PMOD_EXPORT struct svalue *mapping_mapping_string_lookup(struct mapping *m,
    				      struct pike_string *key1,
    				      struct pike_string *key2,
    				      int create)
    {
      struct svalue k1,k2;
      k1.type=T_STRING;
      k1.u.string=key1;
      k2.type=T_STRING;
      k2.u.string=key2;
      return mapping_mapping_lookup(m,&k1,&k2,create);
    }
    
    
    
    PMOD_EXPORT void mapping_index_no_free(struct svalue *dest,
    			   struct mapping *m,
    			   const struct svalue *key)
    {
      struct svalue *p;
    
      if(!IS_DESTRUCTED (key) && (p=low_mapping_lookup(m,key)))
      {
        assign_svalue_no_free(dest, p);
    
        /* Never return NUMBER_UNDEFINED for existing entries. */
        /* Note: There is code that counts on storing UNDEFINED in mapping
         * values (using e.g. low_mapping_lookup to get them), so we have
         * to fix the subtype here rather than in mapping_insert. */
        if(p->type==T_INT)
          dest->subtype=NUMBER_NUMBER;
      }else{
        dest->type=T_INT;
        dest->u.integer=0;
        dest->subtype=NUMBER_UNDEFINED;
      }
    }
    
    PMOD_EXPORT struct array *mapping_indices(struct mapping *m)
    {
      INT32 e;
      struct array *a;
      struct svalue *s;
      struct keypair *k;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      check_mapping_for_destruct(m);
    
      a=allocate_array(m->data->size);
      s=ITEM(a);
    
      /* no locking required */
      NEW_MAPPING_LOOP(m->data) assign_svalue(s++, & k->ind);
    
      a->type_field = m->data->ind_types;
      
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
    
      return a;
    }
    
    PMOD_EXPORT struct array *mapping_values(struct mapping *m)
    {
      INT32 e;
      struct keypair *k;
      struct array *a;
      struct svalue *s;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      check_mapping_for_destruct(m);
    
      a=allocate_array(m->data->size);
      s=ITEM(a);
    
      /* no locking required */
      NEW_MAPPING_LOOP(m->data) assign_svalue(s++, & k->val);
    
      a->type_field = m->data->val_types;
    
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
      
      return a;
    }
    
    PMOD_EXPORT struct array *mapping_to_array(struct mapping *m)
    {
      INT32 e;
      struct keypair *k;
      struct array *a;
      struct svalue *s;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      a=allocate_array(m->data->size);
      s=ITEM(a);
    
      /* no locking required */
      NEW_MAPPING_LOOP(m->data)
        {
          struct array *b=allocate_array(2);
          assign_svalue(b->item+0, & k->ind);
          assign_svalue(b->item+1, & k->val);
          b->type_field = (1 << k->ind.type) | (1 << k->val.type);
          s->u.array=b;
          s->type=T_ARRAY;
          s++;
        }
      a->type_field = BIT_ARRAY;
    
      return a;
    }
    
    PMOD_EXPORT void mapping_replace(struct mapping *m,struct svalue *from, struct svalue *to)
    {
      INT32 e;
      struct keypair *k;
      struct mapping_data *md;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      md=m->data;
      if(md->size)
      {
        add_ref(md);
        NEW_MAPPING_LOOP(md)
          {
    	if(is_eq(& k->val, from))
    	{
    	  PREPARE_FOR_DATA_CHANGE();
    	  assign_svalue(& k->val, to);
    	  md->val_types|=1<<to->type;
    	}
          }
        free_mapping_data(md);
      }
    
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
    }
    
    PMOD_EXPORT struct mapping *mkmapping(struct array *ind, struct array *val)
    {
      struct mapping *m;
      struct svalue *i,*v;
      INT32 e;
    
    #ifdef PIKE_DEBUG
      if(ind->size != val->size)
        Pike_fatal("mkmapping on different sized arrays.\n");
    #endif
    
      m=allocate_mapping(MAP_SLOTS(ind->size));
      i=ITEM(ind);
      v=ITEM(val);
      for(e=0;e<ind->size;e++) low_mapping_insert(m, i++, v++, 2);
    
      return m;
    }
    
    #if 0
    PMOD_EXPORT struct mapping *copy_mapping(struct mapping *m)
    {
      INT32 e;
      struct mapping *n;
      struct keypair *k;
      struct mapping_data *md;
    
      md=m->data;
      n=allocate_mapping(MAP_SLOTS(md->size));
    
      md->valrefs++;
      add_ref(md);
      NEW_MAPPING_LOOP(md) mapping_insert(n, &k->ind, &k->val);
      md->valrefs--;
      free_mapping_data(md);
      
      return n;
    }
    #else
    
    /* deferred mapping copy! */
    PMOD_EXPORT struct mapping *copy_mapping(struct mapping *m)
    {
      struct mapping *n;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      n=allocate_mapping(0);
      debug_malloc_touch(n->data);
      free_mapping_data(n->data);
      n->data=m->data;
    #ifdef MAPPING_SIZE_DEBUG
      n->debug_size=n->data->size;
    #endif
      add_ref(n->data);
      n->data->valrefs++;
      n->data->hardlinks++;
      debug_malloc_touch(n->data);
      return n;
    }
    
    #endif
    
    static struct mapping *subtract_mappings(struct mapping *a, struct mapping *b)
    {
      struct mapping *res;
      struct keypair *k;
      struct mapping_data *a_md = a->data;
      struct mapping_data *b_md = b->data;
      INT32 e;
      ONERROR err;
    
      /* First some special cases. */
      if (!a_md->size || !b_md->size || !a_md->hashsize || !b_md->hashsize) {
        return copy_mapping(a);
      }
      if (a_md == b_md) {
        return allocate_mapping(0);
      }
      /* FIXME: The break-even point should probably be researched. */
      if (a_md->size < b_md->size) {
        /* Add the elements in a that aren't in b. */
        res = allocate_mapping(a_md->size);
        SET_ONERROR(err, do_free_mapping, res);
        NEW_MAPPING_LOOP(a_md) {
          size_t h = k->hval % b_md->hashsize;
          struct keypair *k2;
          for (k2 = b_md->hash[h]; k2; k2 = k2->next) {
    	if ((k2->hval == k->hval) && is_eq(&k2->ind, &k->ind)) {
    	  break;
    	}
          }
          if (!k2) {
    	mapping_insert(res, &k->ind, &k->val);
          }
        }
      } else {
        /* Remove the elements in a that are in b. */
        res = copy_mapping(a);
        SET_ONERROR(err, do_free_mapping, res);
        NEW_MAPPING_LOOP(b_md) {
          map_delete(res, &k->ind);
        }
      }
      UNSET_ONERROR(err);
      return res;
    }
    
    static struct mapping *and_mappings(struct mapping *a, struct mapping *b)
    {
      struct mapping *res;
      struct keypair *k;
      struct mapping_data *a_md = a->data;
      struct mapping_data *b_md = b->data;
      INT32 e;
      ONERROR err;
    
      /* First some special cases. */
      if (!a_md->size || !b_md->size) return allocate_mapping(0);
      if (a_md == b_md) return copy_mapping(a);
    
      /* Copy the second mapping. */
      res = copy_mapping(b);
      SET_ONERROR(err, do_free_mapping, res);
    
      /* Remove elements in res that aren't in a. */
      NEW_MAPPING_LOOP(b_md) {
        size_t h = k->hval % a_md->hashsize;
        struct keypair *k2;
        for (k2 = a_md->hash[h]; k2; k2 = k2->next) {
          if ((k2->hval == k->hval) && is_eq(&k2->ind, &k->ind)) {
    	break;
          }
        }
        if (!k2) {
          map_delete(res, &k->ind);
        }
      }
      UNSET_ONERROR(err);
      return res;
    }
    
    static struct mapping *or_mappings(struct mapping *a, struct mapping *b)
    {
      struct mapping *res;
      struct keypair *k;
      struct mapping_data *a_md = a->data;
      struct mapping_data *b_md = b->data;
      INT32 e;
      ONERROR err;
    
      /* First some special cases. */
      if (!a_md->size) return copy_mapping(b);
      if (!b_md->size) return copy_mapping(a);
      if (a_md == b_md) return copy_mapping(a);
    
      /* Copy the second mapping. */
      res = copy_mapping(b);
      SET_ONERROR(err, do_free_mapping, res);
    
      /* Add elements in a that aren't in b. */
      NEW_MAPPING_LOOP(a_md) {
        size_t h = k->hval % b_md->hashsize;
        struct keypair *k2;
        for (k2 = b_md->hash[h]; k2; k2 = k2->next) {
          if ((k2->hval == k->hval) && is_eq(&k2->ind, &k->ind)) {
    	break;
          }
        }
        if (!k2) {
          mapping_insert(res, &k->ind, &k->val);
        }
      }
      UNSET_ONERROR(err);
      return res;
    }
    
    static struct mapping *xor_mappings(struct mapping *a, struct mapping *b)
    {
      struct mapping *res;
      struct keypair *k;
      struct mapping_data *a_md = a->data;
      struct mapping_data *b_md = b->data;
      INT32 e;
      ONERROR err;
    
      /* First some special cases. */
      if (!a_md->size) return copy_mapping(b);
      if (!b_md->size) return copy_mapping(a);
      if (a_md == b_md) return allocate_mapping(0);
    
      /* Copy the largest mapping. */
      if (a_md->size > b_md->size) {
        struct mapping *tmp = a;
        a = b;
        b = tmp;
        a_md = b_md;
        b_md = b->data;
      }    
      res = copy_mapping(b);
      SET_ONERROR(err, do_free_mapping, res);
    
      /* Add elements in a that aren't in b, and remove those that are. */
      NEW_MAPPING_LOOP(a_md) {
        size_t h = k->hval % b_md->hashsize;
        struct keypair *k2;
        for (k2 = b_md->hash[h]; k2; k2 = k2->next) {
          if ((k2->hval == k->hval) && is_eq(&k2->ind, &k->ind)) {
    	break;
          }
        }
        if (!k2) {
          mapping_insert(res, &k->ind, &k->val);
        } else {
          map_delete(res, &k2->ind);
        }
      }
      UNSET_ONERROR(err);
      return res;
    }
    
    PMOD_EXPORT struct mapping *merge_mappings(struct mapping *a, struct mapping *b, INT32 op)
    {
      ONERROR r1,r2,r3,r4;
      struct array *ai, *av;
      struct array *bi, *bv;
      struct array *ci, *cv;
      INT32 *zipper;
      struct mapping *m;
    
    #ifdef PIKE_DEBUG
      if(a->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
      if(b->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      switch (op) {
      case PIKE_ARRAY_OP_SUB:
        return subtract_mappings(a, b);
      case PIKE_ARRAY_OP_AND:
        return and_mappings(a, b);
      case PIKE_ARRAY_OP_OR:
        return or_mappings(a, b);
      case PIKE_ARRAY_OP_XOR:
        return xor_mappings(a, b);
      }
    
      ai=mapping_indices(a);
      SET_ONERROR(r1,do_free_array,ai);
    
      av=mapping_values(a);
      SET_ONERROR(r2,do_free_array,av);
    
      if(ai->size > 1)
      {
        zipper=get_set_order(ai);
        order_array(ai, zipper);
        order_array(av, zipper);
        free((char *)zipper);
      }
    
      bi=mapping_indices(b);
      SET_ONERROR(r3,do_free_array,bi);
    
      bv=mapping_values(b);
      SET_ONERROR(r4,do_free_array,bv);
    
      if(bi->size > 1)
      {
        zipper=get_set_order(bi);
        order_array(bi, zipper);
        order_array(bv, zipper);
        free((char *)zipper);
      }
    
      zipper=merge(ai,bi,op);
    
      ci=array_zip(ai,bi,zipper);
    
      UNSET_ONERROR(r4); free_array(bi);
      UNSET_ONERROR(r3); free_array(ai);
    
      cv=array_zip(av,bv,zipper);
    
      UNSET_ONERROR(r2); free_array(bv);
      UNSET_ONERROR(r1); free_array(av);
    
      free((char *)zipper);
    
      m=mkmapping(ci, cv);
      free_array(ci);
      free_array(cv);
    
      return m;
    }
    
    /* FIXME: What are the semantics for this function?
     * FIXME: It ought to be optimized just like the unordered variant.
     *	/grubba 2003-11-12
     */
    PMOD_EXPORT struct mapping *merge_mapping_array_ordered(struct mapping *a, 
    					    struct array *b, INT32 op)
    {
      ONERROR r1,r2;
      struct array *ai, *av;
      struct array *ci = NULL, *cv = NULL;
      INT32 *zipper = NULL;
      struct mapping *m;
    
      ai=mapping_indices(a);
      SET_ONERROR(r1,do_free_array,ai);
      av=mapping_values(a);
      SET_ONERROR(r2,do_free_array,av);
      if(ai->size > 1)
      {
        zipper=get_set_order(ai);
        order_array(ai, zipper);
        order_array(av, zipper);
        free((char *)zipper);
      }
    
      switch (op) /* no elements from b may be selected */
      {
         case PIKE_ARRAY_OP_AND:
    	zipper=merge(b,ai,op);
    	ci=array_zip(b,ai,zipper); /* b must not be used */
    	cv=array_zip(b,av,zipper); /* b must not be used */
    	break;
         case PIKE_ARRAY_OP_SUB:
    	zipper=merge(ai,b,op);
    	ci=array_zip(ai,b,zipper); /* b must not be used */
    	cv=array_zip(av,b,zipper); /* b must not be used */
    	break;
         default:
    	Pike_fatal("merge_mapping_array on other than AND or SUB\n");
      }
    
      UNSET_ONERROR(r2); free_array(av);
      UNSET_ONERROR(r1); free_array(ai);
      
      free((char *)zipper);
    
      m=mkmapping(ci, cv);
      free_array(ci);
      free_array(cv);
    
      return m;
    }
    
    PMOD_EXPORT struct mapping *merge_mapping_array_unordered(struct mapping *a, 
    					      struct array *b, INT32 op)
    {
      ONERROR r1;
      struct array *b_temp;
      INT32 *zipper;
      struct mapping *m;
    
      if (b->size>1)
      {
        zipper=get_set_order(b);
        b_temp=reorder_and_copy_array(b,zipper);
        free (zipper);
        SET_ONERROR(r1,do_free_array,b_temp);
        m=merge_mapping_array_ordered(a,b_temp,op);
        UNSET_ONERROR(r1); free_array(b_temp);
      }
      else
        m=merge_mapping_array_ordered(a,b,op);
    
      return m;
    }
    
    PMOD_EXPORT struct mapping *add_mappings(struct svalue *argp, INT32 args)
    {
      INT32 e,d;
      struct mapping *ret=0;
      struct keypair *k;
    
      for(e=d=0;d<args;d++)
      {
    #ifdef PIKE_DEBUG
        if(d_flag>1) check_mapping(argp[d].u.mapping);
    #endif
        e+=argp[d].u.mapping->data->size;
      }
    
      if(!e) return allocate_mapping(0);
    
      d=0;
    
      for(;d<args;d++)
      {
        struct mapping *m=argp[d].u.mapping;
        struct mapping_data *md=m->data;
    
        if(md->size == 0) continue;
    
        if(!(md->flags  & MAPPING_WEAK))
        {
    #if 1 /* major optimization */
          if(e==md->size)
    	return copy_mapping(m);
    #endif
        
          if(m->refs == 1 && !md->hardlinks)
          {
    	add_ref( ret=m );
    	d++;
    	break;
          }
        }
        ret=allocate_mapping(MAP_SLOTS(e));
        break;
    
      }
    
      for(;d<args;d++)
      {
        struct mapping *m=argp[d].u.mapping;
        struct mapping_data *md=m->data;
        
        add_ref(md);
        NEW_MAPPING_LOOP(md)
          low_mapping_insert(ret, &k->ind, &k->val, 2);
        free_mapping_data(md);
      }
    #ifdef PIKE_DEBUG
      if(!ret)
        Pike_fatal("add_mappings is confused!\n");
    #endif
      return ret;
    }
    
    PMOD_EXPORT int mapping_equal_p(struct mapping *a, struct mapping *b, struct processing *p)
    {
      struct processing curr;
      struct keypair *k;
      struct mapping_data *md;
      INT32 e,eq=1;
    
    #ifdef PIKE_DEBUG
      if(a->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
      if(b->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      if(a==b) return 1;
    
      if (a->data == b->data) return 1;
    
      if (a->data->flags || b->data->flags) return 0;
    
      check_mapping_for_destruct(a);
      check_mapping_for_destruct(b);
    
      if(m_sizeof(a) != m_sizeof(b)) return 0;
    
      curr.pointer_a = a;
      curr.pointer_b = b;
      curr.next = p;
    
      for( ;p ;p=p->next)
        if(p->pointer_a == (void *)a && p->pointer_b == (void *)b)
          return 1;
    
      md=a->data;
      md->valrefs++;
      add_ref(md);
    
      NEW_MAPPING_LOOP(md)
      {
        struct svalue *s;
        if((s=low_mapping_lookup(b, & k->ind)))
        {
          if(!low_is_equal(s, &k->val, &curr))
          {
    	eq=0;
    	break;
          }
        }else{
          INT32 d;
          struct mapping_data *bmd = b->data;
          struct keypair *kp;
    
          /* This is neither pretty nor fast, but it should
           * perform a bit more like expected... -Hubbe
           */
    
          bmd->valrefs++;
          add_ref(bmd);
    
          eq=0;
          for(d=0;d<(bmd)->hashsize;d++)
          {
    	for(kp=bmd->hash[d];kp;kp=kp->next)
    	{
    	  if(low_is_equal(&k->ind, &kp->ind, &curr) &&
    	     low_is_equal(&k->val, &kp->val, &curr))
    	  {
    	    eq=1;
    	    break;
    	  }
    	}
          }
    
          bmd->valrefs--;
          free_mapping_data(bmd);
    
          if(!eq) break;
        }
      }
      md->valrefs--;
      free_mapping_data(md);
      return eq;
    }
    
    void describe_mapping(struct mapping *m,struct processing *p,int indent)
    {
      struct processing doing;
      struct array *a;
      JMP_BUF catch;
      ONERROR err;
      INT32 e,d;
      char buf[40];
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      if(! m->data->size)
      {
        my_strcat("([ ])");
        return;
      }
    
      doing.next=p;
      doing.pointer_a=(void *)m;
      for(e=0;p;e++,p=p->next)
      {
        if(p->pointer_a == (void *)m)
        {
          sprintf(buf,"@%ld",(long)e);
          my_strcat(buf);
          return;
        }
      }
    
      if (Pike_in_gc > GC_PASS_PREPARE && Pike_in_gc < GC_PASS_FREE) {
        /* Have to do without any temporary allocations. */
        struct keypair *k;
        int notfirst = 0;
    
        if (m->data->size == 1) {
          my_strcat("([ /* 1 element */\n");
        } else {
          sprintf(buf, "([ /* %ld elements */\n", (long)m->data->size);
          my_strcat(buf);
        }
    
        NEW_MAPPING_LOOP(m->data) {
          if (notfirst) my_strcat(",\n");
          else notfirst = 1;
          for(d = 0; d < indent; d++)
    	my_putchar(' ');
          describe_svalue(&k->ind, indent+2, &doing);
          my_strcat (": ");
          describe_svalue(&k->val, indent+2, &doing);
        }
    
        my_putchar('\n');
        for(e=2; e<indent; e++) my_putchar(' ');
        my_strcat("])");
        return;
      }
    
      a = mapping_indices(m);
      SET_ONERROR(err, do_free_array, a);
    
      if(! m->data->size) {		/* mapping_indices may remove elements */
        my_strcat("([ ])");
      }
      else {
        int save_t_flag = Pike_interpreter.trace_level;
    
        if (m->data->size == 1) {
          my_strcat("([ /* 1 element */\n");
        } else {
          sprintf(buf, "([ /* %ld elements */\n", (long)m->data->size);
          my_strcat(buf);
        }
    
        Pike_interpreter.trace_level = 0;
        if(SETJMP(catch)) {
          free_svalue(&throw_value);
          mark_free_svalue (&throw_value);
        }
        else
          sort_array_destructively(a);
        UNSETJMP(catch);
        Pike_interpreter.trace_level = save_t_flag;
    
        for(e = 0; e < a->size; e++)
        {
          struct svalue *tmp;
          if(e)
    	my_strcat(",\n");
        
          for(d = 0; d < indent; d++)
    	my_putchar(' ');
        
          describe_svalue(ITEM(a)+e, indent+2, &doing);
          my_strcat (": ");
    
          {
    	int save_t_flag=Pike_interpreter.trace_level;
    	Pike_interpreter.trace_level=0;
    	
    	tmp=low_mapping_lookup(m, ITEM(a)+e);
    	
    	Pike_interpreter.trace_level=save_t_flag;
          }
          if(tmp)
    	describe_svalue(tmp, indent+2, &doing);
          else
    	my_strcat("** gone **");
        }
    
        my_putchar('\n');
        for(e=2; e<indent; e++) my_putchar(' ');
        my_strcat("])");
      }
    
      UNSET_ONERROR(err);
      free_array(a);
    }
    
    node *make_node_from_mapping(struct mapping *m)
    {
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
      mapping_fix_type_field(m);
    
      if(!mapping_is_constant(m,0))
      {
        struct array *ind, *val;
        node *n;
        ind=mapping_indices(m);
        val=mapping_values(m);
        n=mkefuncallnode("mkmapping",
    		     mknode(F_ARG_LIST,
    			    make_node_from_array(ind),
    			    make_node_from_array(val)));
        free_array(ind);
        free_array(val);
        return n;
      }else{
        struct svalue s;
    
        if(!m->data->size)
          return mkefuncallnode("aggregate_mapping",0);
    
        s.type=T_MAPPING;
        s.subtype=0;
        s.u.mapping=m;
        return mkconstantsvaluenode(&s);
      }
    }
    
    /*! @decl mapping aggregate_mapping(mixed ... elems)
     *!
     *! Construct a mapping.
     *!
     *! Groups the arguments together two and two in key-index pairs and
     *! creates a mapping of those pairs. Generally, the mapping literal
     *! syntax is handier: @expr{([ key1:val1, key2:val2, ... ])@}
     *!
     *! @seealso
     *!   @[sizeof()], @[mappingp()], @[mkmapping()]
     */
    PMOD_EXPORT void f_aggregate_mapping(INT32 args)
    {
      INT32 e;
      struct mapping *m;
    
      if(args & 1)
        Pike_error("Uneven number of arguments to aggregate_mapping.\n");
    
      m=allocate_mapping(MAP_SLOTS(args / 2));
    
      for(e=-args;e<0;e+=2) {
        STACK_LEVEL_START(-e);
        low_mapping_insert(m, Pike_sp+e, Pike_sp+e+1, 2);
        STACK_LEVEL_DONE(-e);
      }
      pop_n_elems(args);
    #ifdef PIKE_DEBUG
      if(d_flag)
        check_mapping(m);
    #endif
      push_mapping(m);
    }
    
    PMOD_EXPORT struct mapping *copy_mapping_recursively(struct mapping *m,
    						     struct mapping *p)
    {
      struct mapping *ret;
      INT32 e;
      struct keypair *k;
      struct mapping_data  *md;
      struct svalue aa, bb;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
    #ifdef PIKE_DEBUG
      if(d_flag > 1) check_mapping_type_fields(m);
    #endif
    
      if(!((m->data->val_types | m->data->ind_types) & BIT_COMPLEX))
        return copy_mapping(m);
    
      ret=allocate_mapping(MAP_SLOTS(m->data->size));
    
      aa.type = T_MAPPING;
      aa.subtype = 0;
      aa.u.mapping = m;
      bb.type = T_MAPPING;
      bb.subtype = 0;
      bb.u.mapping = ret;
      mapping_insert(p, &aa, &bb);
    
      ret->data->flags = m->data->flags;
    
      check_stack(2);
    
      md=m->data;
      md->valrefs++;
      add_ref(md);
      NEW_MAPPING_LOOP(md)
      {
        /* Place holders.
         *
         * NOTE: copy_svalues_recursively_no_free() may store stuff in
         *       the destination svalue, and then call stuff that uses
         *       the stack (eg itself).
         */
        push_int(0);
        push_int(0);
        copy_svalues_recursively_no_free(Pike_sp-2,&k->ind, 1, p);
        copy_svalues_recursively_no_free(Pike_sp-1,&k->val, 1, p);
        
        low_mapping_insert(ret, Pike_sp-2, Pike_sp-1, 2);
        pop_n_elems(2);
      }
      md->valrefs--;
      free_mapping_data(md);
    
      return ret;
    }
    
    
    PMOD_EXPORT void mapping_search_no_free(struct svalue *to,
    			    struct mapping *m,
    			    const struct svalue *look_for,
    			    const struct svalue *key /* start */)
    {
      struct mapping_data *md, *omd;
    
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
      md=m->data;
    
      if(md->size)
      {
        unsigned INT32 h2,h=0;
        struct keypair *k=md->hash[0], **prev;
    
        if(key)
        {
          h2=hash_svalue(key);
          
          FIND();
          
          if(!k)
          {
    	to->type=T_INT;
    	to->subtype=NUMBER_UNDEFINED;
    	to->u.integer=0;
    	return;
          }
          k=k->next;
        }
        
        
        md=m->data;
        if(md->size)
        {
          md->valrefs++;
          add_ref(md);
          
          if(h < (unsigned INT32)md->hashsize)
          {
    	while(1)
    	{
    	  while(k)
    	  {
    	    if(is_eq(look_for, &k->val))
    	    {
    	      assign_svalue_no_free(to,&k->ind);
    	      
    	      md->valrefs--;
    	      free_mapping_data(md);
    	      return;
    	    }
    	    k=k->next;
    	  }
    	  h++;
    	  if(h>= (unsigned INT32)md->hashsize)
    	    break;
    	  k=md->hash[h];
    	}
          }
        }
        
        md->valrefs--;
        free_mapping_data(md);
      }
    
      to->type=T_INT;
      to->subtype=NUMBER_UNDEFINED;
      to->u.integer=0;
    }
    
    
    #ifdef PIKE_DEBUG
    
    void check_mapping(const struct mapping *m)
    {
      int e,num;
      struct keypair *k;
      const struct mapping_data *md;
    
      static int in_check_mapping;
      if(in_check_mapping) return;
      in_check_mapping=1;
    
      md=m->data;
    
      if(m->refs <=0)
        Pike_fatal("Mapping has zero refs.\n");
    
      if(!m->data)
        Pike_fatal("Mapping has no data block.\n");
    
      if (!m->data->refs)
        Pike_fatal("Mapping data block has zero refs.\n");
    
      if(m->next && m->next->prev != m)
        Pike_fatal("Mapping ->next->prev != mapping.\n");
    
    #ifdef MAPPING_SIZE_DEBUG
      if(m->debug_size != md->size)
      {
        if(Pike_in_gc)
        {
          fprintf(stderr,"Pike was in GC stage %d when this fatal occured:\n",Pike_in_gc);
          Pike_in_gc=0;
        }
        
        fprintf(stderr,"--MAPPING ZAPPING (%d!=%d), mapping:\n",m->debug_size,md->size);
        describe(m);
        fprintf(stderr,"--MAPPING ZAPPING (%d!=%d), mapping data:\n",m->debug_size,md->size);
        describe(md);
        Pike_fatal("Mapping zapping detected (%d != %d)!\n",m->debug_size,md->size);
      }
    #endif
    
      if(m->prev)
      {
        if(m->prev->next != m)
          Pike_fatal("Mapping ->prev->next != mapping.\n");
      }else{
        if(first_mapping != m)
          Pike_fatal("Mapping ->prev == 0 but first_mapping != mapping.\n");
      }
    
      if(md->valrefs <0)
        Pike_fatal("md->valrefs  < 0\n");
    
      if(md->hardlinks <0)
        Pike_fatal("md->valrefs  < 0\n");
    
      if(md->refs < md->valrefs+1)
        Pike_fatal("md->refs < md->valrefs+1\n");
    
      if(md->valrefs < md->hardlinks)
        Pike_fatal("md->refs < md->valrefs+1\n");
    
      if(md->hashsize < 0)
        Pike_fatal("Assert: I don't think he's going to make it Jim.\n");
    
      if(md->size < 0)
        Pike_fatal("Core breach, evacuate ship!\n");
    
      if(md->num_keypairs < 0)
        Pike_fatal("Starboard necell on fire!\n");
    
      if(md->size > md->num_keypairs)
        Pike_fatal("Pretty mean hashtable there buster!\n");
    
      if(md->hashsize > md->num_keypairs)
        Pike_fatal("Pretty mean hashtable there buster %d > %d (2)!\n",md->hashsize,md->num_keypairs);
    
      if(md->num_keypairs > (md->hashsize + 3) * AVG_LINK_LENGTH)
        Pike_fatal("Mapping from hell detected, attempting to send it back...\n");
      
      if(md->size > 0 && (!md->ind_types || !md->val_types))
        Pike_fatal("Mapping type fields are... wrong.\n");
    
      num=0;
      NEW_MAPPING_LOOP(md)
        {
          num++;
    
          if(! ( (1 << k->ind.type) & (md->ind_types) ))
    	Pike_fatal("Mapping indices type field lies.\n");
    
          if(! ( (1 << k->val.type) & (md->val_types) ))
    	Pike_fatal("Mapping values type field lies.\n");
    
          check_svalue(& k->ind);
          check_svalue(& k->val);
    
          /* FIXME add check for k->hval
           * beware that hash_svalue may be threaded and locking
           * is required!!
           */
        }
      
      if(md->size != num)
        Pike_fatal("Shields are failing, hull integrity down to 20%%\n");
    
      in_check_mapping=0;
    }
    
    void check_all_mappings(void)
    {
      struct mapping *m;
      for(m=first_mapping;m;m=m->next)
        check_mapping(m);
    }
    #endif
    
    static void visit_mapping_data (struct mapping_data *md, int action,
    				struct mapping *m)
    {
      switch (action) {
    #ifdef PIKE_DEBUG
        default:
          Pike_fatal ("Unknown visit action %d.\n", action);
        case VISIT_NORMAL:
        case VISIT_COMPLEX_ONLY:
          break;
    #endif
        case VISIT_COUNT_BYTES:
          mc_counted_bytes += MAPPING_DATA_SIZE (md->hashsize, md->num_keypairs);
          break;
      }
    
      if ((md->ind_types | md->val_types) &
          (action & VISIT_COMPLEX_ONLY ? BIT_COMPLEX : BIT_REF_TYPES)) {
        int ind_ref_type =
          md->flags & MAPPING_WEAK_INDICES ? REF_TYPE_WEAK : REF_TYPE_NORMAL;
        int val_ref_type =
          md->flags & MAPPING_WEAK_VALUES ? REF_TYPE_WEAK : REF_TYPE_NORMAL;
        INT32 e;
        struct keypair *k;
        NEW_MAPPING_LOOP (md) {
          visit_svalue (&k->ind, ind_ref_type);
          visit_svalue (&k->val, val_ref_type);
        }
      }
    }
    
    PMOD_EXPORT void visit_mapping (struct mapping *m, int action)
    {
      switch (action) {
    #ifdef PIKE_DEBUG
        default:
          Pike_fatal ("Unknown visit action %d.\n", action);
        case VISIT_NORMAL:
        case VISIT_COMPLEX_ONLY:
          break;
    #endif
        case VISIT_COUNT_BYTES:
          mc_counted_bytes += sizeof (struct mapping);
          break;
      }
    
      visit_ref (m->data, REF_TYPE_INTERNAL,
    	     (visit_thing_fn *) &visit_mapping_data, m);
    }
    
    #ifdef MAPPING_SIZE_DEBUG
    #define DO_IF_MAPPING_SIZE_DEBUG(x) x
    #else
    #define DO_IF_MAPPING_SIZE_DEBUG(x)
    #endif
    
    #define GC_RECURSE_MD_IN_USE(MD, RECURSE_FN, IND_TYPES, VAL_TYPES) do { \
      INT32 e;								\
      struct keypair *k;							\
      IND_TYPES = MD->ind_types;						\
      NEW_MAPPING_LOOP(MD) {						\
        if (!IS_DESTRUCTED(&k->ind) && RECURSE_FN(&k->ind, 1)) {		\
          DO_IF_DEBUG(Pike_fatal("Didn't expect an svalue zapping now.\n")); \
        }									\
        RECURSE_FN(&k->val, 1);						\
        VAL_TYPES |= 1 << k->val.type;					\
      }									\
    } while (0)
    
    #ifdef PIKE_MAPPING_KEYPAIR_LOOP
    #error Broken code below!
    #define GC_RECURSE(M, MD, REC_KEYPAIR, TYPE, IND_TYPES, VAL_TYPES) do {	\
        int remove;								\
        struct keypair *k,**prev_;						\
        /* no locking required (no is_eq) */				\
        for(k = MD_KEYPAIRS(md, md->hashsize);k < MD->free_list;)		\
        {									\
          REC_KEYPAIR(remove,						\
    		  PIKE_CONCAT(TYPE, _svalues),				\
    		  PIKE_CONCAT(TYPE, _weak_svalues),			\
    		  PIKE_CONCAT(TYPE, _without_recurse),			\
    		  PIKE_CONCAT(TYPE, _weak_without_recurse));		\
          if (remove) {							\
    	/* Find and unlink k. */					\
    	unsigned INT32 h_;						\
    	h_ = k->hval % md->hashsize;					\
    	prev_ = md->hash + h_;						\
    	DO_IF_DEBUG(							\
    		    if (!*prev_) {					\
    		      Pike_fatal("Node to unlink not found!\n");	\
    		    }							\
    		    );							\
    	while (*prev_ != k) {						\
    	  prev_ = &((*prev_)->next);					\
    	  DO_IF_DEBUG(							\
    		      if (!*prev_) {					\
    			Pike_fatal("Node to unlink not found!\n");	\
    		      }							\
    		      );						\
    	}								\
    	(*prev_)->next = k->next;					\
            FREE_KEYPAIR(MD, k);						\
    	mark_free_svalue (&MD->free_list->ind);				\
    	mark_free_svalue (&MD->free_list->val);				\
    	MD->size--;							\
    	DO_IF_MAPPING_SIZE_DEBUG(					\
    	  if(M->data ==MD)						\
    	    M->debug_size--;						\
    	);								\
          } else {								\
    	VAL_TYPES |= 1 << k->val.type;					\
    	IND_TYPES |= 1 << k->ind.type;					\
    	k++;								\
          }									\
        }									\
      } while (0)
    #else /* !PIKE_MAPPING_KEYPAIR_LOOP */
    #define GC_RECURSE(M, MD, REC_KEYPAIR, TYPE, IND_TYPES, VAL_TYPES) do {	\
      INT32 e;								\
      int remove;								\
      struct keypair *k,**prev;						\
      /* no locking required (no is_eq) */					\
      for(e=0;e<MD->hashsize;e++)						\
      {									\
        for(prev= MD->hash + e;(k=*prev);)					\
        {									\
          REC_KEYPAIR(remove,						\
    		  PIKE_CONCAT(TYPE, _svalues),				\
    		  PIKE_CONCAT(TYPE, _weak_svalues),			\
    		  PIKE_CONCAT(TYPE, _without_recurse),			\
    		  PIKE_CONCAT(TYPE, _weak_without_recurse));		\
          if (remove)							\
          {									\
    	*prev=k->next;							\
            FREE_KEYPAIR(MD, k);						\
    	mark_free_svalue (&MD->free_list->ind);				\
    	mark_free_svalue (&MD->free_list->val);				\
    	MD->size--;							\
    	DO_IF_MAPPING_SIZE_DEBUG(					\
    	  if(M->data ==MD)						\
    	    M->debug_size--;						\
    	);								\
          }else{								\
    	VAL_TYPES |= 1 << k->val.type;					\
    	IND_TYPES |= 1 << k->ind.type;					\
    	prev=&k->next;							\
          }									\
        }									\
      }									\
    } while (0)
    #endif /* PIKE_MAPPING_KEYPAIR_LOOP */
    
    #define GC_REC_KP(REMOVE, N_REC, W_REC, N_TST, W_TST) do {		\
      if ((REMOVE = N_REC(&k->ind, 1)))					\
        gc_free_svalue(&k->val);						\
      else									\
        N_REC(&k->val, 1);							\
    } while (0)
    
    #define GC_REC_KP_IND(REMOVE, N_REC, W_REC, N_TST, W_TST) do {		\
      if ((REMOVE = W_REC(&k->ind, 1)))					\
        gc_free_svalue(&k->val);						\
      else									\
        N_REC(&k->val, 1);							\
    } while (0)
    
    #define GC_REC_KP_VAL(REMOVE, N_REC, W_REC, N_TST, W_TST) do {		\
      if ((REMOVE = N_TST(&k->ind))) /* Don't recurse now. */		\
        gc_free_svalue(&k->val);						\
      else if ((REMOVE = W_REC(&k->val, 1)))				\
        gc_free_svalue(&k->ind);						\
      else									\
        N_REC(&k->ind, 1);		/* Now we can recurse the index. */	\
    } while (0)
    
    #define GC_REC_KP_BOTH(REMOVE, N_REC, W_REC, N_TST, W_TST) do {		\
      if ((REMOVE = W_TST(&k->ind))) /* Don't recurse now. */		\
        gc_free_svalue(&k->val);						\
      else if ((REMOVE = W_REC(&k->val, 1)))				\
        gc_free_svalue(&k->ind);						\
      else									\
        W_REC(&k->ind, 1);		/* Now we can recurse the index. */	\
    } while (0)
    
    void gc_mark_mapping_as_referenced(struct mapping *m)
    {
    #ifdef PIKE_DEBUG
      if(m->data->refs <=0)
        Pike_fatal("Zero refs in mapping->data\n");
    #endif
      debug_malloc_touch(m);
      debug_malloc_touch(m->data);
    
      if(gc_mark(m))
        GC_ENTER (m, T_MAPPING) {
          struct mapping_data *md = m->data;
    
          if (m == gc_mark_mapping_pos)
    	gc_mark_mapping_pos = m->next;
          if (m == gc_internal_mapping)
    	gc_internal_mapping = m->next;
          else {
    	DOUBLEUNLINK(first_mapping, m);
    	DOUBLELINK(first_mapping, m); /* Linked in first. */
          }
    
          if(gc_mark(md) && ((md->ind_types | md->val_types) & BIT_COMPLEX)) {
    	TYPE_FIELD ind_types = 0, val_types = 0;
    	if (MAPPING_DATA_IN_USE(md)) {
    	  /* Must leave the mapping data untouched if it's busy. */
    	  debug_malloc_touch(m);
    	  debug_malloc_touch(md);
    	  GC_RECURSE_MD_IN_USE(md, gc_mark_svalues, ind_types, val_types);
    	  gc_assert_checked_as_nonweak(md);
    	}
    	else
    	  switch (md->flags & MAPPING_WEAK) {
    	    case 0:
    	      debug_malloc_touch(m);
    	      debug_malloc_touch(md);
    	      GC_RECURSE(m, md, GC_REC_KP, gc_mark, ind_types, val_types);
    	      gc_assert_checked_as_nonweak(md);
    	      break;
    	    case MAPPING_WEAK_INDICES:
    	      debug_malloc_touch(m);
    	      debug_malloc_touch(md);
    	      GC_RECURSE(m, md, GC_REC_KP_IND, gc_mark, ind_types, val_types);
    	      gc_assert_checked_as_weak(md);
    	      break;
    	    case MAPPING_WEAK_VALUES:
    	      debug_malloc_touch(m);
    	      debug_malloc_touch(md);
    	      GC_RECURSE(m, md, GC_REC_KP_VAL, gc_mark, ind_types, val_types);
    	      gc_assert_checked_as_weak(md);
    	      break;
    	    default:
    	      debug_malloc_touch(m);
    	      debug_malloc_touch(md);
    	      GC_RECURSE(m, md, GC_REC_KP_BOTH, gc_mark, ind_types, val_types);
    	      gc_assert_checked_as_weak(md);
    	      break;
    	  }
    	md->val_types = val_types;
    	md->ind_types = ind_types;
          }
        } GC_LEAVE;
    }
    
    void real_gc_cycle_check_mapping(struct mapping *m, int weak)
    {
      GC_CYCLE_ENTER(m, T_MAPPING, weak) {
        struct mapping_data *md = m->data;
        debug_malloc_touch(m);
        debug_malloc_touch(md);
    
    #ifdef PIKE_DEBUG
        if(md->refs <=0)
          Pike_fatal("Zero refs in mapping->data\n");
    #endif
    
        if ((md->ind_types | md->val_types) & BIT_COMPLEX) {
          TYPE_FIELD ind_types = 0, val_types = 0;
          if (MAPPING_DATA_IN_USE(md)) {
    	/* Must leave the mapping data untouched if it's busy. */
    	debug_malloc_touch(m);
    	debug_malloc_touch(md);
    	GC_RECURSE_MD_IN_USE(md, gc_cycle_check_svalues, ind_types, val_types);
    	gc_assert_checked_as_nonweak(md);
          }
          else
    	switch (md->flags & MAPPING_WEAK) {
    	  case 0:
    	    debug_malloc_touch(m);
    	    debug_malloc_touch(md);
    	    GC_RECURSE(m, md, GC_REC_KP, gc_cycle_check, ind_types, val_types);
    	    gc_assert_checked_as_nonweak(md);
    	    break;
    	  case MAPPING_WEAK_INDICES:
    	    debug_malloc_touch(m);
    	    debug_malloc_touch(md);
    	    GC_RECURSE(m, md, GC_REC_KP_IND, gc_cycle_check, ind_types, val_types);
    	    gc_assert_checked_as_weak(md);
    	    break;
    	  case MAPPING_WEAK_VALUES:
    	    debug_malloc_touch(m);
    	    debug_malloc_touch(md);
    	    GC_RECURSE(m, md, GC_REC_KP_VAL, gc_cycle_check, ind_types, val_types);
    	    gc_assert_checked_as_weak(md);
    	    break;
    	  default:
    	    debug_malloc_touch(m);
    	    debug_malloc_touch(md);
    	    GC_RECURSE(m, md, GC_REC_KP_BOTH, gc_cycle_check, ind_types, val_types);
    	    gc_assert_checked_as_weak(md);
    	    break;
    	}
          md->val_types = val_types;
          md->ind_types = ind_types;
        }
      } GC_CYCLE_LEAVE;
    }
    
    static void gc_check_mapping(struct mapping *m)
    {
      struct mapping_data *md = m->data;
    
      if((md->ind_types | md->val_types) & BIT_COMPLEX)
        GC_ENTER (m, T_MAPPING) {
          INT32 e;
          struct keypair *k;
    
          if(!debug_gc_check (md, " as mapping data block of a mapping")) {
    	if (!(md->flags & MAPPING_WEAK) || MAPPING_DATA_IN_USE(md))
    	  /* Disregard the weak flag if the mapping data is busy; we must
    	   * leave it untouched in that case anyway. */
    	  NEW_MAPPING_LOOP(md)
    	  {
    	    debug_gc_check_svalues(&k->ind, 1, " as mapping index");
    	    debug_gc_check_svalues(&k->val, 1, " as mapping value");
    	  }
    	else {
    	  switch (md->flags & MAPPING_WEAK) {
    	    case MAPPING_WEAK_INDICES:
    	      NEW_MAPPING_LOOP(md)
    	      {
    		debug_gc_check_weak_svalues(&k->ind, 1, " as mapping index");
    		debug_gc_check_svalues(&k->val, 1, " as mapping value");
    	      }
    	      break;
    	    case MAPPING_WEAK_VALUES:
    	      NEW_MAPPING_LOOP(md)
    	      {
    		debug_gc_check_svalues(&k->ind, 1, " as mapping index");
    		debug_gc_check_weak_svalues(&k->val, 1, " as mapping value");
    	      }
    	      break;
    	    default:
    	      NEW_MAPPING_LOOP(md)
    	      {
    		debug_gc_check_weak_svalues(&k->ind, 1, " as mapping index");
    		debug_gc_check_weak_svalues(&k->val, 1, " as mapping value");
    	      }
    	      break;
    	  }
    	  gc_checked_as_weak(md);
    	}
          }
        } GC_LEAVE;
    }
    
    unsigned gc_touch_all_mappings(void)
    {
      unsigned n = 0;
      struct mapping *m;
      if (first_mapping && first_mapping->prev)
        Pike_fatal("Error in mapping link list.\n");
      for (m = first_mapping; m; m = m->next) {
        debug_gc_touch(m);
        n++;
        if (m->next && m->next->prev != m)
          Pike_fatal("Error in mapping link list.\n");
      }
      return n;
    }
    
    void gc_check_all_mappings(void)
    {
      struct mapping *m;
    
      for(m=first_mapping;m;m=m->next)
      {
    #ifdef DEBUG_MALLOC
        if (((int) PTR_TO_INT (m->data)) == 0x55555555) {
          fprintf(stderr, "** Zapped mapping in list of active mappings!\n");
          describe_something(m, T_MAPPING, 0,2,0, NULL);
          Pike_fatal("Zapped mapping in list of active mappings!\n");
        }
    #endif /* DEBUG_MALLOC */
    
        gc_check_mapping(m);
    #ifdef PIKE_DEBUG
        if(d_flag > 1) check_mapping_type_fields(m);
    #endif
      }
    }
    
    void gc_mark_all_mappings(void)
    {
      gc_mark_mapping_pos = gc_internal_mapping;
      while (gc_mark_mapping_pos) {
        struct mapping *m = gc_mark_mapping_pos;
        gc_mark_mapping_pos = m->next;
    
        debug_malloc_touch(m);
        debug_malloc_touch(m->data);
    
        if(gc_is_referenced(m))
          gc_mark_mapping_as_referenced(m);
      }
    }
    
    void gc_cycle_check_all_mappings(void)
    {
      struct mapping *m;
      for (m = gc_internal_mapping; m; m = m->next) {
        real_gc_cycle_check_mapping(m, 0);
        gc_cycle_run_queue();
      }
    }
    
    void gc_zap_ext_weak_refs_in_mappings(void)
    {
      gc_mark_mapping_pos = first_mapping;
      while (gc_mark_mapping_pos != gc_internal_mapping && gc_ext_weak_refs) {
        struct mapping *m = gc_mark_mapping_pos;
        gc_mark_mapping_pos = m->next;
        gc_mark_mapping_as_referenced(m);
      }
      gc_mark_discard_queue();
    }
    
    size_t gc_free_all_unreferenced_mappings(void)
    {
      struct mapping *m,*next;
      struct mapping_data *md;
      size_t unreferenced = 0;
    
      for(m=gc_internal_mapping;m;m=next)
      {
        debug_malloc_touch(m);
        debug_malloc_touch(m->data);
    
        if(gc_do_free(m))
        {
          /* Got an extra ref from gc_cycle_pop(). */
          md = m->data;
    
          debug_malloc_touch(m);
          debug_malloc_touch(md);
    
          /* Protect against unlink_mapping_data() recursing too far. */
          m->data=&empty_data;
          add_ref(m->data);
    
          unlink_mapping_data(md);
    #ifdef MAPPING_SIZE_DEBUG
          m->debug_size=0;
    #endif
          gc_free_extra_ref(m);
          SET_NEXT_AND_FREE(m, free_mapping);
        }
        else
        {
          next=m->next;
        }
        unreferenced++;
      }
    
      return unreferenced;
    }
    
    #ifdef PIKE_DEBUG
    
    void simple_describe_mapping(struct mapping *m)
    {
      dynamic_buffer save_buf;
      char *s;
      init_buf(&save_buf);
      describe_mapping(m,0,2);
      s=simple_free_buf(&save_buf);
      fprintf(stderr,"%s\n",s);
      free(s);
    }
    
    
    void debug_dump_mapping(struct mapping *m)
    {
      fprintf(stderr, "Refs=%d, next=%p, prev=%p",
    	  m->refs, m->next, m->prev);
      if (((ptrdiff_t)m->data) & 3) {
        fprintf(stderr, ", data=%p (unaligned)\n", m->data);
      } else {
        fprintf(stderr, ", flags=0x%x, size=%d, hashsize=%d\n",
    	    m->data->flags, m->data->size, m->data->hashsize);
        fprintf(stderr, "Indices type field =");
        debug_dump_type_field(m->data->ind_types);
        fprintf(stderr, "\n");
        fprintf(stderr, "Values type field =");
        debug_dump_type_field(m->data->val_types);
        fprintf(stderr, "\n");
        simple_describe_mapping(m);
      }
    }
    #endif
    
    int mapping_is_constant(struct mapping *m,
    			struct processing *p)
    {
      int ret=1;
      INT32 e;
      struct keypair *k;
      struct mapping_data *md=m->data;
    
      if( (md->ind_types | md->val_types) & ~(BIT_INT|BIT_FLOAT|BIT_STRING))
      {
        md->valrefs++;
        add_ref(md);
        NEW_MAPPING_LOOP(md)
          {
    	if(!svalues_are_constant(&k->ind, 1, md->ind_types, p) ||
    	   !svalues_are_constant(&k->val, 1, md->val_types, p))
    	{
    	  ret=0;
    	  e=md->hashsize;
    	  break;
    	}
          }
        md->valrefs--;
        free_mapping_data(md);
      }
      return ret;
    }