text: /* pgm.h - header file for libpgm portable graymap library
  */
  
  #ifndef _PGM_H_
  #define _PGM_H_
  
  
  #include "pbm.h"
  
  #ifdef PGM_BIGGRAYS
  typedef unsigned short gray;
  #define PGM_MAXMAXVAL 65535
  #else /*PGM_BIGGRAYS*/
  typedef unsigned char gray;
  #define PGM_MAXMAXVAL 255
  #endif /*PGM_BIGGRAYS*/
  
  
  /* Magic constants. */
  
  #define PGM_MAGIC1 'P'
  #define PGM_MAGIC2 '2'
  #define RPGM_MAGIC2 '5'
  #define PGM_FORMAT (PGM_MAGIC1 * 256 + PGM_MAGIC2)
  #define RPGM_FORMAT (PGM_MAGIC1 * 256 + RPGM_MAGIC2)
  #define PGM_TYPE PGM_FORMAT
  
  
  /* Macro for turning a format number into a type number. */
  
  #define PGM_FORMAT_TYPE(f) ((f) == PGM_FORMAT || (f) == RPGM_FORMAT ? PGM_TYPE : PBM_FORMAT_TYPE(f))
  
  
  /* Declarations of routines. */
  
  void pgm_init ARGS(( int* argcP, char* argv[] ));
  
  #define pgm_allocarray( cols, rows ) ((gray**) pm_allocarray( cols, rows, sizeof(gray) ))
  #define pgm_allocrow( cols ) ((gray*) nzalloc( cols, sizeof(gray), "pgm-row"))
  #define pgm_freearray( grays, rows ) pm_freearray( (char**) grays, rows )
  #define pgm_freerow( grayrow ) pm_freerow( (char*) grayrow )
  
  gray** pgm_readpgm ARGS(( FILE* file, int* colsP, int* rowsP, gray* maxvalP ));
  int pgm_readpgminit ARGS(( FILE* file, int* colsP, int* rowsP, gray* maxvalP, int* formatP ));
  int pgm_readpgmrow ARGS(( FILE* file, gray* grayrow, int cols, gray maxval, int format ));
  
  void pgm_writepgm ARGS(( FILE* file, gray** grays, int cols, int rows, gray maxval, int forceplain ));
  void pgm_writepgminit ARGS(( FILE* file, int cols, int rows, gray maxval, int forceplain ));
  void pgm_writepgmrow ARGS(( FILE* file, gray* grayrow, int cols, gray maxval, int forceplain ));
  
  extern gray pgm_pbmmaxval;
  /* This is the maxval used when a PGM program reads a PBM file.  Normally
  ** it is 1; however, for some programs, a larger value gives better results
  */
  
  #endif /*_PGM_H_*/
  