/* png.c - location for general purpose libpng functions

 *

 * libpng version 1.2.5 - October 3, 2002

 * 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.)

 *

 */

#define PNG_INTERNAL

#define PNG_NO_EXTERN

#include "png.h"

/* Generate a compiler error if there is an old png.h in the search path. */

typedef version_1_2_5 Your_png_h_is_not_version_1_2_5;

/* Version information for C files.  This had better match the version

 * string defined in png.h.  */

#ifdef PNG_USE_GLOBAL_ARRAYS

/* png_libpng_ver was changed to a function in version 1.0.5c */

const char png_libpng_ver[18] = "1.2.5";

/* png_sig was changed to a function in version 1.0.5c */

/* Place to hold the signature string for a PNG file. */

const png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};

/* Invoke global declarations for constant strings for known chunk types */

PNG_IHDR;

PNG_IDAT;

PNG_IEND;

PNG_PLTE;

PNG_bKGD;

PNG_cHRM;

PNG_gAMA;

PNG_hIST;

PNG_iCCP;

PNG_iTXt;

PNG_oFFs;

PNG_pCAL;

PNG_sCAL;

PNG_pHYs;

PNG_sBIT;

PNG_sPLT;

PNG_sRGB;

PNG_tEXt;

PNG_tIME;

PNG_tRNS;

PNG_zTXt;

/* arrays to facilitate easy interlacing - use pass (0 - 6) as index */

/* start of interlace block */

const int FARDATA png_pass_start[] = {0, 4, 0, 2, 0, 1, 0};

/* offset to next interlace block */

const int FARDATA png_pass_inc[] = {8, 8, 4, 4, 2, 2, 1};

/* start of interlace block in the y direction */

const int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};

/* offset to next interlace block in the y direction */

const int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};

/* width of interlace block (used in assembler routines only) */

#ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW

const int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};

#endif

/* Height of interlace block.  This is not currently used - if you need

 * it, uncomment it here and in png.h

const int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};

*/

/* Mask to determine which pixels are valid in a pass */

const int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};

/* Mask to determine which pixels to overwrite while displaying */

const int FARDATA png_pass_dsp_mask[]

   = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};

#endif

/* Tells libpng that we have already handled the first "num_bytes" bytes

 * of the PNG file signature.  If the PNG data is embedded into another

 * stream we can set num_bytes = 8 so that libpng will not attempt to read

 * or write any of the magic bytes before it starts on the IHDR.

 */

void PNGAPI

png_set_sig_bytes(png_structp png_ptr, int num_bytes)

{

   png_debug(1, "in png_set_sig_bytes\n");

   if (num_bytes > 8)

      png_error(png_ptr, "Too many bytes for PNG signature.");

   png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);

}

/* Checks whether the supplied bytes match the PNG signature.  We allow

 * checking less than the full 8-byte signature so that those apps that

 * already read the first few bytes of a file to determine the file type

 * can simply check the remaining bytes for extra assurance.  Returns

 * an integer less than, equal to, or greater than zero if sig is found,

 * respectively, to be less than, to match, or be greater than the correct

 * PNG signature (this is the same behaviour as strcmp, memcmp, etc).

 */

int PNGAPI

png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)

{

   png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};

   if (num_to_check > 8)

      num_to_check = 8;

   else if (num_to_check < 1)

      return (0);

   if (start > 7)

      return (0);

   if (start + num_to_check > 8)

      num_to_check = 8 - start;

   return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));

}

/* (Obsolete) function to check signature bytes.  It does not allow one

 * to check a partial signature.  This function might be removed in the

 * future - use png_sig_cmp().  Returns true (nonzero) if the file is a PNG.

 */

int PNGAPI

png_check_sig(png_bytep sig, int num)

{

  return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));

}

/* Function to allocate memory for zlib and clear it to 0. */

#ifdef PNG_1_0_X

voidpf PNGAPI

#else

voidpf /* private */

#endif

png_zalloc(voidpf png_ptr, uInt items, uInt size)

{

   png_uint_32 num_bytes = (png_uint_32)items * size;

   png_voidp ptr;

   png_structp p=png_ptr;

   png_uint_32 save_flags=p->flags;

   p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;

   ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);

   p->flags=save_flags;

#ifndef PNG_NO_ZALLOC_ZERO

   if (ptr == NULL)

       return ((voidpf)ptr);

   if (num_bytes > (png_uint_32)0x8000L)

   {

      png_memset(ptr, 0, (png_size_t)0x8000L);

      png_memset((png_bytep)ptr + (png_size_t)0x8000L, 0,

         (png_size_t)(num_bytes - (png_uint_32)0x8000L));

   }

   else

   {

      png_memset(ptr, 0, (png_size_t)num_bytes);

   }

#endif

   return ((voidpf)ptr);

}

/* function to free memory for zlib */

#ifdef PNG_1_0_X

void PNGAPI

#else

void /* private */

#endif

png_zfree(voidpf png_ptr, voidpf ptr)

{

   png_free((png_structp)png_ptr, (png_voidp)ptr);

}

/* Reset the CRC variable to 32 bits of 1's.  Care must be taken

 * in case CRC is > 32 bits to leave the top bits 0.

 */

void /* PRIVATE */

png_reset_crc(png_structp png_ptr)

{

   png_ptr->crc = crc32(0, Z_NULL, 0);

}

/* Calculate the CRC over a section of data.  We can only pass as

 * much data to this routine as the largest single buffer size.  We

 * also check that this data will actually be used before going to the

 * trouble of calculating it.

 */

void /* PRIVATE */

png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)

{

   int need_crc = 1;

   if (png_ptr->chunk_name[0] & 0x20)                     /* ancillary */

   {

      if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==

          (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))

         need_crc = 0;

   }

   else                                                    /* critical */

   {

      if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)

         need_crc = 0;

   }

   if (need_crc)

      png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length);

}

/* Allocate the memory for an info_struct for the application.  We don't

 * really need the png_ptr, but it could potentially be useful in the

 * future.  This should be used in favour of malloc(sizeof(png_info))

 * and png_info_init() so that applications that want to use a shared

 * libpng don't have to be recompiled if png_info changes size.

 */

png_infop PNGAPI

png_create_info_struct(png_structp png_ptr)

{

   png_infop info_ptr;

   png_debug(1, "in png_create_info_struct\n");

   if(png_ptr == NULL) return (NULL);

#ifdef PNG_USER_MEM_SUPPORTED

   info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,

      png_ptr->malloc_fn, png_ptr->mem_ptr);

#else

   info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);

#endif

   if (info_ptr != NULL)

      png_info_init_3(&info_ptr, sizeof(png_info));

   return (info_ptr);

}

/* This function frees the memory associated with a single info struct.

 * Normally, one would use either png_destroy_read_struct() or

 * png_destroy_write_struct() to free an info struct, but this may be

 * useful for some applications.

 */

void PNGAPI

png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)

{

   png_infop info_ptr = NULL;

   png_debug(1, "in png_destroy_info_struct\n");

   if (info_ptr_ptr != NULL)

      info_ptr = *info_ptr_ptr;

   if (info_ptr != NULL)

   {

      png_info_destroy(png_ptr, info_ptr);

#ifdef PNG_USER_MEM_SUPPORTED

      png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,

          png_ptr->mem_ptr);

#else

      png_destroy_struct((png_voidp)info_ptr);

#endif

      *info_ptr_ptr = NULL;

   }

}

/* Initialize the info structure.  This is now an internal function (0.89)

 * and applications using it are urged to use png_create_info_struct()

 * instead.

 */

#undef png_info_init

void PNGAPI

png_info_init(png_infop info_ptr)

{

   /* We only come here via pre-1.0.12-compiled applications */

   png_info_init_3(&info_ptr, 0);

}

void PNGAPI

png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)

{

   png_infop info_ptr = *ptr_ptr;

   png_debug(1, "in png_info_init_3\n");

   if(sizeof(png_info) > png_info_struct_size)

     {

       png_destroy_struct(info_ptr);

       info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);

       *ptr_ptr = info_ptr;

     }

   /* set everything to 0 */

   png_memset(info_ptr, 0, sizeof (png_info));

}

#ifdef PNG_FREE_ME_SUPPORTED

void PNGAPI

png_data_freer(png_structp png_ptr, png_infop info_ptr,

   int freer, png_uint_32 mask)

{

   png_debug(1, "in png_data_freer\n");

   if (png_ptr == NULL || info_ptr == NULL)

      return;

   if(freer == PNG_DESTROY_WILL_FREE_DATA)

      info_ptr->free_me |= mask;

   else if(freer == PNG_USER_WILL_FREE_DATA)

      info_ptr->free_me &= ~mask;

   else

      png_warning(png_ptr,

         "Unknown freer parameter in png_data_freer.");

}

#endif

void PNGAPI

png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,

   int num)

{

   png_debug(1, "in png_free_data\n");

   if (png_ptr == NULL || info_ptr == NULL)

      return;

#if defined(PNG_TEXT_SUPPORTED)

/* free text item num or (if num == -1) all text items */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)

#else

if (mask & PNG_FREE_TEXT)

#endif

{

   if (num != -1)

   {

     if (info_ptr->text && info_ptr->text[num].key)

     {

         png_free(png_ptr, info_ptr->text[num].key);

         info_ptr->text[num].key = NULL;

     }

   }

   else

   {

       int i;

       for (i = 0; i < info_ptr->num_text; i++)

           png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);

       png_free(png_ptr, info_ptr->text);

       info_ptr->text = NULL;

       info_ptr->num_text=0;

   }

}

#endif

#if defined(PNG_tRNS_SUPPORTED)

/* free any tRNS entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)

#else

if ((mask & PNG_FREE_TRNS) && (png_ptr->flags & PNG_FLAG_FREE_TRNS))

#endif

{

    png_free(png_ptr, info_ptr->trans);

    info_ptr->valid &= ~PNG_INFO_tRNS;

#ifndef PNG_FREE_ME_SUPPORTED

    png_ptr->flags &= ~PNG_FLAG_FREE_TRNS;

#endif

    info_ptr->trans = NULL;

}

#endif

#if defined(PNG_sCAL_SUPPORTED)

/* free any sCAL entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)

#else

if (mask & PNG_FREE_SCAL)

#endif

{

#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED)

    png_free(png_ptr, info_ptr->scal_s_width);

    png_free(png_ptr, info_ptr->scal_s_height);

    info_ptr->scal_s_width = NULL;

    info_ptr->scal_s_height = NULL;

#endif

    info_ptr->valid &= ~PNG_INFO_sCAL;

}

#endif

#if defined(PNG_pCAL_SUPPORTED)

/* free any pCAL entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)

#else

if (mask & PNG_FREE_PCAL)

#endif

{

    png_free(png_ptr, info_ptr->pcal_purpose);

    png_free(png_ptr, info_ptr->pcal_units);

    info_ptr->pcal_purpose = NULL;

    info_ptr->pcal_units = NULL;

    if (info_ptr->pcal_params != NULL)

    {

        int i;

        for (i = 0; i < (int)info_ptr->pcal_nparams; i++)

        {

          png_free(png_ptr, info_ptr->pcal_params[i]);

          info_ptr->pcal_params[i]=NULL;

        }

        png_free(png_ptr, info_ptr->pcal_params);

        info_ptr->pcal_params = NULL;

    }

    info_ptr->valid &= ~PNG_INFO_pCAL;

}

#endif

#if defined(PNG_iCCP_SUPPORTED)

/* free any iCCP entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)

#else

if (mask & PNG_FREE_ICCP)

#endif

{

    png_free(png_ptr, info_ptr->iccp_name);

    png_free(png_ptr, info_ptr->iccp_profile);

    info_ptr->iccp_name = NULL;

    info_ptr->iccp_profile = NULL;

    info_ptr->valid &= ~PNG_INFO_iCCP;

}

#endif

#if defined(PNG_sPLT_SUPPORTED)

/* free a given sPLT entry, or (if num == -1) all sPLT entries */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)

#else

if (mask & PNG_FREE_SPLT)

#endif

{

   if (num != -1)

   {

      if(info_ptr->splt_palettes)

      {

          png_free(png_ptr, info_ptr->splt_palettes[num].name);

          png_free(png_ptr, info_ptr->splt_palettes[num].entries);

          info_ptr->splt_palettes[num].name = NULL;

          info_ptr->splt_palettes[num].entries = NULL;

      }

   }

   else

   {

       if(info_ptr->splt_palettes_num)

       {

         int i;

         for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)

            png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);

         png_free(png_ptr, info_ptr->splt_palettes);

         info_ptr->splt_palettes = NULL;

         info_ptr->splt_palettes_num = 0;

       }

       info_ptr->valid &= ~PNG_INFO_sPLT;

   }

}

#endif

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)

#else

if (mask & PNG_FREE_UNKN)

#endif

{

   if (num != -1)

   {

       if(info_ptr->unknown_chunks)

       {

          png_free(png_ptr, info_ptr->unknown_chunks[num].data);

          info_ptr->unknown_chunks[num].data = NULL;

       }

   }

   else

   {

       int i;

       if(info_ptr->unknown_chunks_num)

       {

         for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)

            png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);

         png_free(png_ptr, info_ptr->unknown_chunks);

         info_ptr->unknown_chunks = NULL;

         info_ptr->unknown_chunks_num = 0;

       }

   }

}

#endif

#if defined(PNG_hIST_SUPPORTED)

/* free any hIST entry */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)

#else

if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))

#endif

{

    png_free(png_ptr, info_ptr->hist);

    info_ptr->hist = NULL;

    info_ptr->valid &= ~PNG_INFO_hIST;

#ifndef PNG_FREE_ME_SUPPORTED

    png_ptr->flags &= ~PNG_FLAG_FREE_HIST;

#endif

}

#endif

/* free any PLTE entry that was internally allocated */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)

#else

if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))

#endif

{

    png_zfree(png_ptr, info_ptr->palette);

    info_ptr->palette = NULL;

    info_ptr->valid &= ~PNG_INFO_PLTE;

#ifndef PNG_FREE_ME_SUPPORTED

    png_ptr->flags &= ~PNG_FLAG_FREE_PLTE;

#endif

    info_ptr->num_palette = 0;

}

#if defined(PNG_INFO_IMAGE_SUPPORTED)

/* free any image bits attached to the info structure */

#ifdef PNG_FREE_ME_SUPPORTED

if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)

#else

if (mask & PNG_FREE_ROWS)

#endif

{

    if(info_ptr->row_pointers)

    {

       int row;

       for (row = 0; row < (int)info_ptr->height; row++)

       {

          png_free(png_ptr, info_ptr->row_pointers[row]);

          info_ptr->row_pointers[row]=NULL;

       }

       png_free(png_ptr, info_ptr->row_pointers);

       info_ptr->row_pointers=NULL;

    }

    info_ptr->valid &= ~PNG_INFO_IDAT;

}

#endif

#ifdef PNG_FREE_ME_SUPPORTED

   if(num == -1)

     info_ptr->free_me &= ~mask;

   else

     info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);

#endif

}

/* This is an internal routine to free any memory that the info struct is

 * pointing to before re-using it or freeing the struct itself.  Recall

 * that png_free() checks for NULL pointers for us.

 */

void /* PRIVATE */

png_info_destroy(png_structp png_ptr, png_infop info_ptr)

{

   png_debug(1, "in png_info_destroy\n");

   png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)

   if (png_ptr->num_chunk_list)

   {

       png_free(png_ptr, png_ptr->chunk_list);

       png_ptr->chunk_list=NULL;

       png_ptr->num_chunk_list=0;

   }

#endif

   png_info_init_3(&info_ptr, sizeof(png_info));

}

/* This function returns a pointer to the io_ptr associated with the user

 * functions.  The application should free any memory associated with this

 * pointer before png_write_destroy() or png_read_destroy() are called.

 */

png_voidp PNGAPI

png_get_io_ptr(png_structp png_ptr)

{

   return (png_ptr->io_ptr);

}

#if !defined(PNG_NO_STDIO)

/* Initialize the default input/output functions for the PNG file.  If you

 * use your own read or write routines, you can call either png_set_read_fn()

 * or png_set_write_fn() instead of png_init_io().  If you have defined

 * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't

 * necessarily available.

 */

void PNGAPI

png_init_io(png_structp png_ptr, png_FILE_p fp)

{

   png_debug(1, "in png_init_io\n");

   png_ptr->io_ptr = (png_voidp)fp;

}

#endif

#if defined(PNG_TIME_RFC1123_SUPPORTED)

/* Convert the supplied time into an RFC 1123 string suitable for use in

 * a "Creation Time" or other text-based time string.

 */

png_charp PNGAPI

png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)

{

   static PNG_CONST char short_months[12][4] =

        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",

         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

   if (png_ptr->time_buffer == NULL)

   {

      png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*

         sizeof(char)));

   }

#if defined(_WIN32_WCE)

   {

      wchar_t time_buf[29];

      wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),

          ptime->day % 32, short_months[(ptime->month - 1) % 12],

        ptime->year, ptime->hour % 24, ptime->minute % 60,

          ptime->second % 61);

      WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,

          NULL, NULL);

   }

#else

#ifdef USE_FAR_KEYWORD

   {

      char near_time_buf[29];

      sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",

          ptime->day % 32, short_months[(ptime->month - 1) % 12],

          ptime->year, ptime->hour % 24, ptime->minute % 60,

          ptime->second % 61);

      png_memcpy(png_ptr->time_buffer, near_time_buf,

          29*sizeof(char));

   }

#else

   sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",

       ptime->day % 32, short_months[(ptime->month - 1) % 12],

       ptime->year, ptime->hour % 24, ptime->minute % 60,

       ptime->second % 61);

#endif

#endif /* _WIN32_WCE */

   return ((png_charp)png_ptr->time_buffer);

}

#endif /* PNG_TIME_RFC1123_SUPPORTED */

#if 0

/* Signature string for a PNG file. */

png_bytep PNGAPI

png_sig_bytes(void)

{

   return ((png_bytep)"\211\120\116\107\015\012\032\012");

}

#endif

png_charp PNGAPI

png_get_copyright(png_structp png_ptr)

{

   if (png_ptr != NULL || png_ptr == NULL)  /* silence compiler warning */

   return ((png_charp) "\n libpng version 1.2.5 - October 3, 2002\n\

   Copyright (c) 1998-2002 Glenn Randers-Pehrson\n\

   Copyright (c) 1996-1997 Andreas Dilger\n\

   Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");

   return ((png_charp) "");

}

/* The following return the library version as a short string in the

 * format 1.0.0 through 99.99.99zz.  To get the version of *.h files used

 * with your application, print out PNG_LIBPNG_VER_STRING, which is defined

 * in png.h.

 */

png_charp PNGAPI

png_get_libpng_ver(png_structp png_ptr)

{

   /* Version of *.c files used when building libpng */

   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */

      return((png_charp) "1.2.5");

   return((png_charp) "1.2.5");

}

png_charp PNGAPI

png_get_header_ver(png_structp png_ptr)

{

   /* Version of *.h files used when building libpng */

   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */

      return((png_charp) PNG_LIBPNG_VER_STRING);

   return((png_charp) PNG_LIBPNG_VER_STRING);

}

png_charp PNGAPI

png_get_header_version(png_structp png_ptr)

{

   /* Returns longer string containing both version and date */

   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */

      return((png_charp) PNG_HEADER_VERSION_STRING);

   return((png_charp) PNG_HEADER_VERSION_STRING);

}

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED

int PNGAPI

png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)

{

   /* check chunk_name and return "keep" value if it's on the list, else 0 */

   int i;

   png_bytep p;

   if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0)

      return 0;

   p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5;

   for (i = png_ptr->num_chunk_list; i; i--, p-=5)

      if (!png_memcmp(chunk_name, p, 4))

        return ((int)*(p+4));

   return 0;

}

#endif

/* This function, added to libpng-1.0.6g, is untested. */

int PNGAPI

png_reset_zstream(png_structp png_ptr)

{

   return (inflateReset(&png_ptr->zstream));

}

/* This function was added to libpng-1.0.7 */

png_uint_32 PNGAPI

png_access_version_number(void)

{

   /* Version of *.c files used when building libpng */

   return((png_uint_32) 10205L);

}

#if !defined(PNG_1_0_X)

#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)

    /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */

/* this INTERNAL function was added to libpng 1.2.0 */

void /* PRIVATE */

png_init_mmx_flags (png_structp png_ptr)

{

    png_ptr->mmx_rowbytes_threshold = 0;

    png_ptr->mmx_bitdepth_threshold = 0;

#  if (defined(PNG_USE_PNGVCRD) || defined(PNG_USE_PNGGCCRD))

    png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_COMPILED;

    if (png_mmx_support() > 0) {

        png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU

#    ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW

                              | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW

#    endif

#    ifdef PNG_HAVE_ASSEMBLER_READ_INTERLACE

                              | PNG_ASM_FLAG_MMX_READ_INTERLACE

#    endif

#    ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW

                              ;

#    else

                              | PNG_ASM_FLAG_MMX_READ_FILTER_SUB

                              | PNG_ASM_FLAG_MMX_READ_FILTER_UP

                              | PNG_ASM_FLAG_MMX_READ_FILTER_AVG

                              | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;

        png_ptr->mmx_rowbytes_threshold = PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT;

        png_ptr->mmx_bitdepth_threshold = PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT;

#    endif

    } else {

        png_ptr->asm_flags &= ~( PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU

                               | PNG_MMX_READ_FLAGS

                               | PNG_MMX_WRITE_FLAGS );

    }

#  else /* !((PNGVCRD || PNGGCCRD) && PNG_ASSEMBLER_CODE_SUPPORTED)) */

    /* clear all MMX flags; no support is compiled in */

    png_ptr->asm_flags &= ~( PNG_MMX_FLAGS );

#  endif /* ?(PNGVCRD || PNGGCCRD) */

}

#endif /* !(PNG_ASSEMBLER_CODE_SUPPORTED) */

/* this function was added to libpng 1.2.0 */

#if !defined(PNG_USE_PNGGCCRD) && \

    !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD))

int PNGAPI

png_mmx_support(void)

{

    return -1;

}

#endif

#endif /* PNG_1_0_X */