/* libpgm1.c - pgm utility library part 1
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
*/

#include <stdio.h>
#include "pgm.h"
#include "libpgm.h"
#include "pbm.h"
#include "libpbm.h"

void
pgm_readpgminitrest( file, colsP, rowsP, maxvalP )
FILE *file;
int *colsP, *rowsP;
gray *maxvalP;
    {
    /* Read size. */
    *colsP = pbm_getint( file );
    *rowsP = pbm_getint( file );

    /* Read maxval. */
    *maxvalP = pbm_getint( file );
    if ( *maxvalP > PGM_MAXMAXVAL )
	pm_error(
	    "maxval too large - %d > %d\n", *maxvalP, PGM_MAXMAXVAL, 0,0,0 );
    }

static bit *bitrow;

gray pgm_pbmmaxval = 1;

void
pgm_readpgminit( file, colsP, rowsP, maxvalP, formatP )
FILE *file;
int *colsP, *rowsP, *formatP;
gray *maxvalP;
    {
    /* Check magic number. */
    *formatP = pbm_readmagicnumber( file );
    switch ( *formatP )
	{
        case PGM_FORMAT:
        case RPGM_FORMAT:
	pgm_readpgminitrest( file, colsP, rowsP, maxvalP );
	break;

        case PBM_FORMAT:
        case RPBM_FORMAT:
	pbm_readpbminitrest( file, colsP, rowsP );
	*maxvalP = pgm_pbmmaxval;
	bitrow = pbm_allocrow( *colsP );
	break;

	default:
	pm_error( "bad magic number - not a pgm or pbm file", 0,0,0,0,0 );
	}
    }

void
pgm_readpgmrow( file, grayrow, cols, maxval, format )
FILE *file;
gray *grayrow;
int cols, format;
gray maxval;
    {
    register int col;
    register gray *gP;
    register bit *bP;

    switch ( format )
	{
	case PGM_FORMAT:
	for ( col = 0, gP = grayrow; col < cols; col++, gP++ )
	    {
	    *gP = pbm_getint( file );
#ifdef DEBUG
	    if ( *gP > maxval )
		pm_error( "value out of bounds (%u > %u)", *gP, maxval, 0,0,0 );
#endif DEBUG
	    }
	break;
	
	case RPGM_FORMAT:
	for ( col = 0, gP = grayrow; col < cols; col++, gP++ )
	    {
	    *gP = pbm_getrawbyte( file );
#ifdef DEBUG
	    if ( *gP > maxval )
		pm_error( "value out of bounds (%u > %u)", *gP, maxval, 0,0,0 );
#endif DEBUG
	    }
	break;
	
	case PBM_FORMAT:
	case RPBM_FORMAT:
	pbm_readpbmrow( file, bitrow, cols, format );
	for ( col = 0, gP = grayrow, bP = bitrow; col < cols; col++, gP++, bP++ )
	    *gP = ( *bP == PBM_WHITE ) ? maxval : 0;
	break;

	default:
	pm_error( "can't happen", 0,0,0,0,0 );
	}
    }

gray **
pgm_readpgm( file, colsP, rowsP, maxvalP )
FILE *file;
int *colsP, *rowsP;
gray *maxvalP;
    {
    gray **grays;
    int row;
    int format;

    pgm_readpgminit( file, colsP, rowsP, maxvalP, &format );

    grays = pgm_allocarray( *colsP, *rowsP );

    for ( row = 0; row < *rowsP; row++ )
	pgm_readpgmrow( file, grays[row], *colsP, *maxvalP, format );

    return grays;
    }