text: 
  /* pngmem.c - stub functions for memory allocation
   *
   * libpng 1.2.5 - October 3, 2002
   * For conditions of distribution and use, see copyright notice in png.h
   * Copyright (c) 1998-2002 Glenn Randers-Pehrson
   * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   *
   * This file provides a location for all memory allocation.  Users who
   * need special memory handling are expected to supply replacement
   * functions for png_malloc() and png_free(), and to use
   * png_create_read_struct_2() and png_create_write_struct_2() to
   * identify the replacement functions.
   */
  
  #define PNG_INTERNAL
  #include "png.h"
  
  /* Borland DOS special memory handler */
  #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
  /* if you change this, be sure to change the one in png.h also */
  
  /* Allocate memory for a png_struct.  The malloc and memset can be replaced
     by a single call to calloc() if this is thought to improve performance. */
  png_voidp /* PRIVATE */
  png_create_struct(int type)
  {
  #ifdef PNG_USER_MEM_SUPPORTED
     return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
  }
  
  /* Alternate version of png_create_struct, for use with user-defined malloc. */
  png_voidp /* PRIVATE */
  png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
  {
  #endif /* PNG_USER_MEM_SUPPORTED */
     png_size_t size;
     png_voidp struct_ptr;
  
     if (type == PNG_STRUCT_INFO)
       size = sizeof(png_info);
     else if (type == PNG_STRUCT_PNG)
       size = sizeof(png_struct);
     else
       return (png_get_copyright());
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if(malloc_fn != NULL)
     {
        png_struct dummy_struct;
        png_structp png_ptr = &dummy_struct;
        png_ptr->mem_ptr=mem_ptr;
        struct_ptr = (*(malloc_fn))(png_ptr, (png_uint_32)size);
     }
     else
  #endif /* PNG_USER_MEM_SUPPORTED */
        struct_ptr = (png_voidp)farmalloc(size));
     if (struct_ptr != NULL)
        png_memset(struct_ptr, 0, size);
     return (struct_ptr);
  }
  
  /* Free memory allocated by a png_create_struct() call */
  void /* PRIVATE */
  png_destroy_struct(png_voidp struct_ptr)
  {
  #ifdef PNG_USER_MEM_SUPPORTED
     png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
  }
  
  /* Free memory allocated by a png_create_struct() call */
  void /* PRIVATE */
  png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
      png_voidp mem_ptr)
  {
  #endif
     if (struct_ptr != NULL)
     {
  #ifdef PNG_USER_MEM_SUPPORTED
        if(free_fn != NULL)
        {
           png_struct dummy_struct;
           png_structp png_ptr = &dummy_struct;
           png_ptr->mem_ptr=mem_ptr;
           (*(free_fn))(png_ptr, struct_ptr);
           return;
        }
  #endif /* PNG_USER_MEM_SUPPORTED */
        farfree (struct_ptr);
     }
  }
  
  /* Allocate memory.  For reasonable files, size should never exceed
   * 64K.  However, zlib may allocate more then 64K if you don't tell
   * it not to.  See zconf.h and png.h for more information. zlib does
   * need to allocate exactly 64K, so whatever you call here must
   * have the ability to do that.
   *
   * Borland seems to have a problem in DOS mode for exactly 64K.
   * It gives you a segment with an offset of 8 (perhaps to store its
   * memory stuff).  zlib doesn't like this at all, so we have to
   * detect and deal with it.  This code should not be needed in
   * Windows or OS/2 modes, and only in 16 bit mode.  This code has
   * been updated by Alexander Lehmann for version 0.89 to waste less
   * memory.
   *
   * Note that we can't use png_size_t for the "size" declaration,
   * since on some systems a png_size_t is a 16-bit quantity, and as a
   * result, we would be truncating potentially larger memory requests
   * (which should cause a fatal error) and introducing major problems.
   */
  
  png_voidp PNGAPI
  png_malloc(png_structp png_ptr, png_uint_32 size)
  {
     png_voidp ret;
  
     if (png_ptr == NULL || size == 0)
        return (NULL);
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if(png_ptr->malloc_fn != NULL)
     {
         ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
         if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
            png_error(png_ptr, "Out of memory!");
         return (ret);
     }
     else
         return png_malloc_default(png_ptr, size);
  }
  
  png_voidp PNGAPI
  png_malloc_default(png_structp png_ptr, png_uint_32 size)
  {
     png_voidp ret;
  #endif /* PNG_USER_MEM_SUPPORTED */
  
  #ifdef PNG_MAX_MALLOC_64K
     if (size > (png_uint_32)65536L)
        png_error(png_ptr, "Cannot Allocate > 64K");
  #endif
  
     if (size == (png_uint_32)65536L)
     {
        if (png_ptr->offset_table == NULL)
        {
           /* try to see if we need to do any of this fancy stuff */
           ret = farmalloc(size);
           if (ret == NULL || ((png_size_t)ret & 0xffff))
           {
              int num_blocks;
              png_uint_32 total_size;
              png_bytep table;
              int i;
              png_byte huge * hptr;
  
              if (ret != NULL)
              {
                 farfree(ret);
                 ret = NULL;
              }
  
              if(png_ptr->zlib_window_bits > 14)
                 num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
              else
                 num_blocks = 1;
              if (png_ptr->zlib_mem_level >= 7)
                 num_blocks += (int)(1 << (png_ptr->zlib_mem_level - 7));
              else
                 num_blocks++;
  
              total_size = ((png_uint_32)65536L) * (png_uint_32)num_blocks+16;
  
              table = farmalloc(total_size);
  
              if (table == NULL)
              {
                 if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                    png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
                 else
                    png_warning(png_ptr, "Out Of Memory.");
                 return (NULL);
              }
  
              if ((png_size_t)table & 0xfff0)
              {
                 if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                    png_error(png_ptr,
                      "Farmalloc didn't return normalized pointer");
                 else
                    png_warning(png_ptr,
                      "Farmalloc didn't return normalized pointer");
                 return (NULL);
              }
  
              png_ptr->offset_table = table;
              png_ptr->offset_table_ptr = farmalloc(num_blocks *
                 sizeof (png_bytep));
  
              if (png_ptr->offset_table_ptr == NULL)
              {
                 if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
                    png_error(png_ptr, "Out Of memory."); /* Note "O" and "M" */
                 else
                    png_warning(png_ptr, "Out Of memory.");
                 return (NULL);
              }
  
              hptr = (png_byte huge *)table;
              if ((png_size_t)hptr & 0xf)
              {
                 hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
                 hptr = hptr + 16L;  /* "hptr += 16L" fails on Turbo C++ 3.0 */
              }
              for (i = 0; i < num_blocks; i++)
              {
                 png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
                 hptr = hptr + (png_uint_32)65536L;  /* "+=" fails on TC++3.0 */
              }
  
              png_ptr->offset_table_number = num_blocks;
              png_ptr->offset_table_count = 0;
              png_ptr->offset_table_count_free = 0;
           }
        }
  
        if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
        {
           if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
              png_error(png_ptr, "Out of Memory."); /* Note "o" and "M" */
           else
              png_warning(png_ptr, "Out of Memory.");
           return (NULL);
        }
  
        ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
     }
     else
        ret = farmalloc(size);
  
     if (ret == NULL)
     {
        if (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
           png_error(png_ptr, "Out of memory."); /* Note "o" and "m" */
        else
           png_warning(png_ptr, "Out of memory."); /* Note "o" and "m" */
     }
  
     return (ret);
  }
  
  /* free a pointer allocated by png_malloc().  In the default
     configuration, png_ptr is not used, but is passed in case it
     is needed.  If ptr is NULL, return without taking any action. */
  void PNGAPI
  png_free(png_structp png_ptr, png_voidp ptr)
  {
     if (png_ptr == NULL || ptr == NULL)
        return;
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if (png_ptr->free_fn != NULL)
     {
        (*(png_ptr->free_fn))(png_ptr, ptr);
        return;
     }
     else png_free_default(png_ptr, ptr);
  }
  
  void PNGAPI
  png_free_default(png_structp png_ptr, png_voidp ptr)
  {
  #endif /* PNG_USER_MEM_SUPPORTED */
  
     if (png_ptr->offset_table != NULL)
     {
        int i;
  
        for (i = 0; i < png_ptr->offset_table_count; i++)
        {
           if (ptr == png_ptr->offset_table_ptr[i])
           {
              ptr = NULL;
              png_ptr->offset_table_count_free++;
              break;
           }
        }
        if (png_ptr->offset_table_count_free == png_ptr->offset_table_count)
        {
           farfree(png_ptr->offset_table);
           farfree(png_ptr->offset_table_ptr);
           png_ptr->offset_table = NULL;
           png_ptr->offset_table_ptr = NULL;
        }
     }
  
     if (ptr != NULL)
     {
        farfree(ptr);
     }
  }
  
  #else /* Not the Borland DOS special memory handler */
  
  /* Allocate memory for a png_struct or a png_info.  The malloc and
     memset can be replaced by a single call to calloc() if this is thought
     to improve performance noticably. */
  png_voidp /* PRIVATE */
  png_create_struct(int type)
  {
  #ifdef PNG_USER_MEM_SUPPORTED
     return (png_create_struct_2(type, png_malloc_ptr_NULL, png_voidp_NULL));
  }
  
  /* Allocate memory for a png_struct or a png_info.  The malloc and
     memset can be replaced by a single call to calloc() if this is thought
     to improve performance noticably. */
  png_voidp /* PRIVATE */
  png_create_struct_2(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)
  {
  #endif /* PNG_USER_MEM_SUPPORTED */
     png_size_t size;
     png_voidp struct_ptr;
  
     if (type == PNG_STRUCT_INFO)
        size = sizeof(png_info);
     else if (type == PNG_STRUCT_PNG)
        size = sizeof(png_struct);
     else
        return (NULL);
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if(malloc_fn != NULL)
     {
        png_struct dummy_struct;
        png_structp png_ptr = &dummy_struct;
        png_ptr->mem_ptr=mem_ptr;
        struct_ptr = (*(malloc_fn))(png_ptr, size);
        if (struct_ptr != NULL)
           png_memset(struct_ptr, 0, size);
        return (struct_ptr);
     }
  #endif /* PNG_USER_MEM_SUPPORTED */
  
  #if defined(__TURBOC__) && !defined(__FLAT__)
     if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
  #else
  # if defined(_MSC_VER) && defined(MAXSEG_64K)
     if ((struct_ptr = (png_voidp)halloc(size,1)) != NULL)
  # else
     if ((struct_ptr = (png_voidp)malloc(size)) != NULL)
  # endif
  #endif
     {
        png_memset(struct_ptr, 0, size);
     }
  
     return (struct_ptr);
  }
  
  
  /* Free memory allocated by a png_create_struct() call */
  void /* PRIVATE */
  png_destroy_struct(png_voidp struct_ptr)
  {
  #ifdef PNG_USER_MEM_SUPPORTED
     png_destroy_struct_2(struct_ptr, png_free_ptr_NULL, png_voidp_NULL);
  }
  
  /* Free memory allocated by a png_create_struct() call */
  void /* PRIVATE */
  png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
      png_voidp mem_ptr)
  {
  #endif /* PNG_USER_MEM_SUPPORTED */
     if (struct_ptr != NULL)
     {
  #ifdef PNG_USER_MEM_SUPPORTED
        if(free_fn != NULL)
        {
           png_struct dummy_struct;
           png_structp png_ptr = &dummy_struct;
           png_ptr->mem_ptr=mem_ptr;
           (*(free_fn))(png_ptr, struct_ptr);
           return;
        }
  #endif /* PNG_USER_MEM_SUPPORTED */
  #if defined(__TURBOC__) && !defined(__FLAT__)
        farfree(struct_ptr);
  #else
  # if defined(_MSC_VER) && defined(MAXSEG_64K)
        hfree(struct_ptr);
  # else
        free(struct_ptr);
  # endif
  #endif
     }
  }
  
  /* Allocate memory.  For reasonable files, size should never exceed
     64K.  However, zlib may allocate more then 64K if you don't tell
     it not to.  See zconf.h and png.h for more information.  zlib does
     need to allocate exactly 64K, so whatever you call here must
     have the ability to do that. */
  
  png_voidp PNGAPI
  png_malloc(png_structp png_ptr, png_uint_32 size)
  {
     png_voidp ret;
  
     if (png_ptr == NULL || size == 0)
        return (NULL);
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if(png_ptr->malloc_fn != NULL)
     {
         ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
         if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
            png_error(png_ptr, "Out of Memory!");
         return (ret);
     }
     else
         return (png_malloc_default(png_ptr, size));
  }
  
  png_voidp PNGAPI
  png_malloc_default(png_structp png_ptr, png_uint_32 size)
  {
     png_voidp ret;
  #endif /* PNG_USER_MEM_SUPPORTED */
  
  #ifdef PNG_MAX_MALLOC_64K
     if (size > (png_uint_32)65536L)
     {
        if(png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
           png_error(png_ptr, "Cannot Allocate > 64K");
        else
           return NULL;
     }
  #endif
  
  #if defined(__TURBOC__) && !defined(__FLAT__)
     ret = farmalloc(size);
  #else
  # if defined(_MSC_VER) && defined(MAXSEG_64K)
     ret = halloc(size, 1);
  # else
     ret = malloc((size_t)size);
  # endif
  #endif
  
     if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
        png_error(png_ptr, "Out of Memory");
  
     return (ret);
  }
  
  /* Free a pointer allocated by png_malloc().  If ptr is NULL, return
     without taking any action. */
  void PNGAPI
  png_free(png_structp png_ptr, png_voidp ptr)
  {
     if (png_ptr == NULL || ptr == NULL)
        return;
  
  #ifdef PNG_USER_MEM_SUPPORTED
     if (png_ptr->free_fn != NULL)
     {
        (*(png_ptr->free_fn))(png_ptr, ptr);
        return;
     }
     else png_free_default(png_ptr, ptr);
  }
  void PNGAPI
  png_free_default(png_structp png_ptr, png_voidp ptr)
  {
     if (png_ptr == NULL || ptr == NULL)
        return;
  
  #endif /* PNG_USER_MEM_SUPPORTED */
  
  #if defined(__TURBOC__) && !defined(__FLAT__)
     farfree(ptr);
  #else
  # if defined(_MSC_VER) && defined(MAXSEG_64K)
     hfree(ptr);
  # else
     free(ptr);
  # endif
  #endif
  }
  
  #endif /* Not Borland DOS special memory handler */
  
  #if defined(PNG_1_0_X)
  #  define png_malloc_warn png_malloc
  #else
  /* This function was added at libpng version 1.2.3.  The png_malloc_warn()
   * function will issue a png_warning and return NULL instead of issuing a
   * png_error, if it fails to allocate the requested memory.
   */
  png_voidp PNGAPI
  png_malloc_warn(png_structp png_ptr, png_uint_32 size)
  {
     png_voidp ptr;
     png_uint_32 save_flags=png_ptr->flags;
  
     png_ptr->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
     ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
     png_ptr->flags=save_flags;
     return(ptr);
  }
  #endif
  
  png_voidp PNGAPI
  png_memcpy_check (png_structp png_ptr, png_voidp s1, png_voidp s2,
     png_uint_32 length)
  {
     png_size_t size;
  
     size = (png_size_t)length;
     if ((png_uint_32)size != length)
        png_error(png_ptr,"Overflow in png_memcpy_check.");
  
     return(png_memcpy (s1, s2, size));
  }
  
  png_voidp PNGAPI
  png_memset_check (png_structp png_ptr, png_voidp s1, int value,
     png_uint_32 length)
  {
     png_size_t size;
  
     size = (png_size_t)length;
     if ((png_uint_32)size != length)
        png_error(png_ptr,"Overflow in png_memset_check.");
  
     return (png_memset (s1, value, size));
  
  }
  
  #ifdef PNG_USER_MEM_SUPPORTED
  /* This function is called when the application wants to use another method
   * of allocating and freeing memory.
   */
  void PNGAPI
  png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr, png_malloc_ptr
    malloc_fn, png_free_ptr free_fn)
  {
     png_ptr->mem_ptr = mem_ptr;
     png_ptr->malloc_fn = malloc_fn;
     png_ptr->free_fn = free_fn;
  }
  
  /* This function returns a pointer to the mem_ptr associated with the user
   * functions.  The application should free any memory associated with this
   * pointer before png_write_destroy and png_read_destroy are called.
   */
  png_voidp PNGAPI
  png_get_mem_ptr(png_structp png_ptr)
  {
     return ((png_voidp)png_ptr->mem_ptr);
  }
  #endif /* PNG_USER_MEM_SUPPORTED */
  