    /* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
     *
     * Copyright (c) 1998-2011 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.)
     *
     * Last changed in libpng 1.5.0 [January 6, 2011]
     *
     * This code is released under the libpng license.
     * For conditions of distribution and use, see the disclaimer
     * and license in png.h
     */

    /* Define PNG_DEBUG at compile time for debugging information.  Higher
     * numbers for PNG_DEBUG mean more debugging information.  This has
     * only been added since version 0.95 so it is not implemented throughout
     * libpng yet, but more support will be added as needed.
     *
     * png_debug[1-2]?(level, message ,arg{0-2})
     *   Expands to a statement (either a simple expression or a compound
     *   do..while(0) statement) that outputs a message with parameter
     *   substitution if PNG_DEBUG is defined to 2 or more.  If PNG_DEBUG
     *   is undefined, 0 or 1 every png_debug expands to a simple expression
     *   (actually ((void)0)).
     *
     *   level: level of detail of message, starting at 0.  A level 'n'
     *          message is preceded by 'n' tab characters (not implemented
     *          on Microsoft compilers unless PNG_DEBUG_FILE is also
     *          defined, to allow debug DLL compilation with no standard IO).
     *   message: a printf(3) style text string.  A trailing '\n' is added
     *            to the message.
     *   arg: 0 to 2 arguments for printf(3) style substitution in message.
     */
    #ifndef PNGDEBUG_H
    #define PNGDEBUG_H
    /* These settings control the formatting of messages in png.c and pngerror.c */
    /* Moved to pngdebug.h at 1.5.0 */
    #  ifndef PNG_LITERAL_SHARP
    #    define PNG_LITERAL_SHARP 0x23
    #  endif
    #  ifndef PNG_LITERAL_LEFT_SQUARE_BRACKET
    #    define PNG_LITERAL_LEFT_SQUARE_BRACKET 0x5b
    #  endif
    #  ifndef PNG_LITERAL_RIGHT_SQUARE_BRACKET
    #    define PNG_LITERAL_RIGHT_SQUARE_BRACKET 0x5d
    #  endif
    #  ifndef PNG_STRING_NEWLINE
    #    define PNG_STRING_NEWLINE "\n"
    #  endif

    #ifdef PNG_DEBUG
    #  if (PNG_DEBUG > 0)
    #    if !defined(PNG_DEBUG_FILE) && defined(_MSC_VER)
    #      include <crtdbg.h>
    #      if (PNG_DEBUG > 1)
    #        ifndef _DEBUG
    #          define _DEBUG
    #        endif
    #        ifndef png_debug
    #          define png_debug(l,m)  _RPT0(_CRT_WARN,m PNG_STRING_NEWLINE)
    #        endif
    #        ifndef png_debug1
    #          define png_debug1(l,m,p1)  _RPT1(_CRT_WARN,m PNG_STRING_NEWLINE,p1)
    #        endif
    #        ifndef png_debug2
    #          define png_debug2(l,m,p1,p2) \
                 _RPT2(_CRT_WARN,m PNG_STRING_NEWLINE,p1,p2)
    #        endif
    #      endif
    #    else /* PNG_DEBUG_FILE || !_MSC_VER */
    #      ifndef PNG_STDIO_SUPPORTED
    #        include <stdio.h> /* not included yet */
    #      endif
    #      ifndef PNG_DEBUG_FILE
    #        define PNG_DEBUG_FILE stderr
    #      endif /* PNG_DEBUG_FILE */

    #      if (PNG_DEBUG > 1)
    /* Note: ["%s"m PNG_STRING_NEWLINE] probably does not work on
     * non-ISO compilers
     */
    #        ifdef __STDC__
    #          ifndef png_debug
    #            define png_debug(l,m) \
           do { \
           int num_tabs=l; \
           fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":"")))); \
           } while (0)
    #          endif
    #          ifndef png_debug1
    #            define png_debug1(l,m,p1) \
           do { \
           int num_tabs=l; \
           fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1); \
           } while (0)
    #          endif
    #          ifndef png_debug2
    #            define png_debug2(l,m,p1,p2) \
           do { \
           int num_tabs=l; \
           fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1,p2); \
           } while (0)
    #          endif
    #        else /* __STDC __ */
    #          ifndef png_debug
    #            define png_debug(l,m) \
           do { \
           int num_tabs=l; \
           char format[256]; \
           snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
             m,PNG_STRING_NEWLINE); \
           fprintf(PNG_DEBUG_FILE,format); \
           } while (0)
    #          endif
    #          ifndef png_debug1
    #            define png_debug1(l,m,p1) \
           do { \
           int num_tabs=l; \
           char format[256]; \
           snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
             m,PNG_STRING_NEWLINE); \
           fprintf(PNG_DEBUG_FILE,format,p1); \
           } while (0)
    #          endif
    #          ifndef png_debug2
    #            define png_debug2(l,m,p1,p2) \
           do { \
           int num_tabs=l; \
           char format[256]; \
           snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
             (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
             m,PNG_STRING_NEWLINE); \
           fprintf(PNG_DEBUG_FILE,format,p1,p2); \
           } while (0)
    #          endif
    #        endif /* __STDC __ */
    #      endif /* (PNG_DEBUG > 1) */

    #    endif /* _MSC_VER */
    #  endif /* (PNG_DEBUG > 0) */
    #endif /* PNG_DEBUG */
    #ifndef png_debug
    #  define png_debug(l, m) ((void)0)
    #endif
    #ifndef png_debug1
    #  define png_debug1(l, m, p1) ((void)0)
    #endif
    #ifndef png_debug2
    #  define png_debug2(l, m, p1, p2) ((void)0)
    #endif
    #endif /* PNGDEBUG_H */