/* libpnmrw.c - PBM/PGM/PPM read/write library
**
** Copyright (C) 1988, 1989, 1991, 1992 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.
*/

#if defined(SVR2) || defined(SVR3) || defined(SVR4)
#ifndef SYSV
#define SYSV
#endif
#endif
#if ! ( defined(BSD) || defined(SYSV) || defined(MSDOS) )
/* CONFIGURE: If your system is >= 4.2BSD, set the BSD option; if you're a
** System V site, set the SYSV option; and if you're IBM-compatible, set
** MSDOS.  If your compiler is ANSI C, you're probably better off setting
** SYSV - all it affects is string handling.
*/
#define BSD
/* #define SYSV */
/* #define MSDOS */
#endif

#include <stdio.h>
#include "libpnmrw.h"

#ifdef SYSV
#include <string.h>
#define rindex(s,c) strrchr(s,c)
#else /*SYSV*/
#include <strings.h>
#endif /*SYSV*/

void *malloc(int);
void free(void *);


/* Definitions. */

#define pbm_allocarray( cols, rows ) ((bit**) pm_allocarray( cols, rows, sizeof(bit) ))
#define pbm_allocrow( cols ) ((bit*) pm_allocrow( cols, sizeof(bit) ))
#define pbm_freearray( bits, rows ) pm_freearray( (char**) bits, rows )
#define pbm_freerow( bitrow ) pm_freerow( (char*) bitrow )
#define pgm_allocarray( cols, rows ) ((gray**) pm_allocarray( cols, rows, sizeof(gray) ))
#define pgm_allocrow( cols ) ((gray*) pm_allocrow( cols, sizeof(gray) ))
#define pgm_freearray( grays, rows ) pm_freearray( (char**) grays, rows )
#define pgm_freerow( grayrow ) pm_freerow( (char*) grayrow )
#define ppm_allocarray( cols, rows ) ((pixel**) pm_allocarray( cols, rows, sizeof(pixel) ))
#define ppm_allocrow( cols ) ((pixel*) pm_allocrow( cols, sizeof(pixel) ))
#define ppm_freearray( pixels, rows ) pm_freearray( (char**) pixels, rows )
#define ppm_freerow( pixelrow ) pm_freerow( (char*) pixelrow )


/* Variables. */

static char* progname;


/* Variable-sized arrays. */

char*
pm_allocrow( cols, size )
    int cols;
    int size;
    {
    register char* itrow;

    itrow = (char*) malloc( cols * size );
    if ( itrow == (char*) 0 )
	{
	(void) fprintf(
	    stderr, "%s: out of memory allocating a row\n", progname );
	return (char*) 0;
	}
    return itrow;
    }

void
pm_freerow( itrow )
    char* itrow;
    {
    free( itrow );
    }

char**
pm_allocarray( cols, rows, size )
    int cols, rows;
    int size;
    {
    char** its;
    int i;

    its = (char**) malloc( rows * sizeof(char*) );
    if ( its == (char**) 0 )
	{
	(void) fprintf(
	    stderr, "%s: out of memory allocating an array\n", progname );
	return (char**) 0;
	}
    its[0] = (char*) malloc( rows * cols * size );
    if ( its[0] == (char*) 0 )
	{
	(void) fprintf(
	    stderr, "%s: out of memory allocating an array\n", progname );
	free( (char*) its );
	return (char**) 0;
	}
    for ( i = 1; i < rows; ++i )
	its[i] = &(its[0][i * cols * size]);
    return its;
    }

void
pm_freearray( its, rows )
    char** its;
    int rows;
    {
    free( its[0] );
    free( its );
    }


/* File open/close that handles "-" as stdin and checks errors. */

static void
pm_perror( reason )
    char* reason;
    {
    extern char* sys_errlist[];
    extern int errno;
    char* e;

    e = sys_errlist[errno];

    if ( reason != 0 && reason[0] != '\0' )
	(void) fprintf( stderr, "%s: %s - %s\n", progname, reason, e );
    else
	(void) fprintf( stderr, "%s: %s\n", progname, e );
    }

FILE*
pm_openr( name )
    char* name;
    {
    FILE* f;

    if ( strcmp( name, "-" ) == 0 )
	f = stdin;
    else
	{
#ifdef MSDOS
	f = fopen( name, "rb" );
#else /*MSDOS*/
	f = fopen( name, "r" );
#endif /*MSDOS*/
	if ( f == NULL )
	    {
	    pm_perror( name );
	    return (FILE*) 0;
	    }
	}
    return f;
    }

FILE*
pm_openw( name )
    char* name;
    {
    FILE* f;

#ifdef MSDOS
    f = fopen( name, "wb" );
#else /*MSDOS*/
    f = fopen( name, "w" );
#endif /*MSDOS*/
    if ( f == NULL )
	{
	pm_perror( name );
	return (FILE*) 0;
	}
    return f;
    }

int
pm_closer( f )
    FILE* f;
    {
    if ( ferror( f ) )
	{
	(void) fprintf(
	    stderr, "%s: a file read error occurred at some point\n",
	    progname );
	return -1;
	}
    if ( f != stdin )
	if ( fclose( f ) != 0 )
	    {
	    pm_perror( "fclose" );
	    return -1;
	    }
    return 0;
    }

int
pm_closew( f )
    FILE* f;
    {
    fflush( f );
    if ( ferror( f ) )
	{
	(void) fprintf(
	    stderr, "%s: a file write error occurred at some point\n",
	    progname );
	return -1;
	}
    if ( f != stdout )
	if ( fclose( f ) != 0 )
	    {
	    pm_perror( "fclose" );
	    return -1;
	    }
    return 0;
    }

static int
pbm_getc( file )
    FILE* file;
    {
    register int ich;

    ich = getc( file );
    if ( ich == EOF )
	{
	(void) fprintf( stderr, "%s: EOF / read error\n", progname );
	return EOF;
	}
    
    if ( ich == '#' )
	{
	do
	    {
	    ich = getc( file );
	    if ( ich == EOF )
		{
		(void) fprintf( stderr, "%s: EOF / read error\n", progname );
		return EOF;
		}
	    }
	while ( ich != '\n' && ich != '\r' );
	}

    return ich;
    }

static bit
pbm_getbit( file )
    FILE* file;
    {
    register int ich;

    do
	{
	ich = pbm_getc( file );
	if ( ich == EOF )
	    return -1;
	}
    while ( ich == ' ' || ich == '\t' || ich == '\n' || ich == '\r' );

    if ( ich != '0' && ich != '1' )
	{
	(void) fprintf(
	    stderr, "%s: junk in file where bits should be\n", progname );
	return -1;
	}

    return ( ich == '1' ) ? 1 : 0;
    }

static int
pbm_readmagicnumber( file )
    FILE* file;
    {
    int ich1, ich2;

    ich1 = getc( file );
    if ( ich1 == EOF )
	{
	(void) fprintf(
	    stderr, "%s: EOF / read error reading magic number\n", progname );
	return -1;
	}
    ich2 = getc( file );
    if ( ich2 == EOF )
	{
	(void) fprintf(
	    stderr, "%s: EOF / read error reading magic number\n", progname );
	return -1;
	}
    return ich1 * 256 + ich2;
    }

static int
pbm_getint( file )
    FILE* file;
    {
    register char ich;
    register int i;

    do
	{
	ich = pbm_getc( file );
	if ( ich == EOF )
	    return -1;
	}
    while ( ich == ' ' || ich == '\t' || ich == '\n' || ich == '\r' );

    if ( ich < '0' || ich > '9' )
	{
	(void) fprintf(
	    stderr, "%s: junk in file where an integer should be\n", progname );
	return -1;
	}

    i = 0;
    do
	{
	i = i * 10 + ich - '0';
	ich = pbm_getc( file );
	if ( ich == EOF )
	    return -1;
        }
    while ( ich >= '0' && ich <= '9' );

    return i;
    }

static int
pbm_readpbminitrest( file, colsP, rowsP )
    FILE* file;
    int* colsP;
    int* rowsP;
    {
    /* Read size. */
    *colsP = pbm_getint( file );
    *rowsP = pbm_getint( file );
    if ( *colsP == -1 || *rowsP == -1 )
	return -1;
    return 0;
    }

static int
pbm_getrawbyte( file )
    FILE* file;
    {
    register int iby;

    iby = getc( file );
    if ( iby == EOF )
	{
	(void) fprintf( stderr, "%s: EOF / read error\n", progname );
	return -1;
	}
    return iby;
    }

static int
pbm_readpbmrow( file, bitrow, cols, format )
    FILE* file;
    bit* bitrow;
    int cols, format;
    {
    register int col, bitshift, b;
    register int item;
    register bit* bP;

    switch ( format )
	{
	case PBM_FORMAT:
	for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
	    {
	    b = pbm_getbit( file );
	    if ( b == -1 )
		return -1;
	    *bP = b;
	    }
	break;

	case RPBM_FORMAT:
	bitshift = -1;
	for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
	    {
	    if ( bitshift == -1 )
		{
		item = pbm_getrawbyte( file );
		if ( item == -1 )
		    return -1;
		bitshift = 7;
		}
	    *bP = ( item >> bitshift ) & 1;
	    --bitshift;
	    }
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

static void
pbm_writepbminit( file, cols, rows, forceplain )
    FILE* file;
    int cols, rows;
    int forceplain;
    {
    if ( ! forceplain )
	(void) fprintf(
	    file, "%c%c\n%d %d\n", PBM_MAGIC1, RPBM_MAGIC2, cols, rows );
    else
	(void) fprintf(
	    file, "%c%c\n%d %d\n", PBM_MAGIC1, PBM_MAGIC2, cols, rows );
    }

static void
pbm_writepbmrowraw( file, bitrow, cols )
    FILE* file;
    bit* bitrow;
    int cols;
    {
    register int col, bitshift;
    register unsigned char item;
    register bit* bP;

    bitshift = 7;
    item = 0;
    for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
	{
	if ( *bP )
	    item += 1 << bitshift;
	--bitshift;
	if ( bitshift == -1 )
	    {
	    (void) putc( item, file );
	    bitshift = 7;
	    item = 0;
	    }
	}
    if ( bitshift != 7 )
	(void) putc( item, file );
    }

static void
pbm_writepbmrowplain( file, bitrow, cols )
    FILE* file;
    bit* bitrow;
    int cols;
    {
    register int col, charcount;
    register bit* bP;

    charcount = 0;
    for ( col = 0, bP = bitrow; col < cols; ++col, ++bP )
	{
	if ( charcount >= 70 )
	    {
	    (void) putc( '\n', file );
	    charcount = 0;
	    }
	putc( *bP ? '1' : '0', file );
	++charcount;
	}
    (void) putc( '\n', file );
    }

static void
pbm_writepbmrow( file, bitrow, cols, forceplain )
    FILE* file;
    bit* bitrow;
    int cols;
    int forceplain;
    {
    if ( ! forceplain )
	pbm_writepbmrowraw( file, bitrow, cols );
    else
	pbm_writepbmrowplain( file, bitrow, cols );
    }

static int
pgm_readpgminitrest( file, colsP, rowsP, maxvalP )
    FILE* file;
    int* colsP;
    int* rowsP;
    gray* maxvalP;
    {
    int maxval;

    /* Read size. */
    *colsP = pbm_getint( file );
    *rowsP = pbm_getint( file );
    if ( *colsP == -1 || *rowsP == -1 )
	return -1;

    /* Read maxval. */
    maxval = pbm_getint( file );
    if ( maxval == -1 )
	return -1;
    if ( maxval > PGM_MAXMAXVAL )
	{
	(void) fprintf( stderr, "%s: maxval is too large\n", progname );
	return -1;
	}
    *maxvalP = maxval;
    return 0;
    }

#if __STDC__
static int
pgm_readpgmrow( FILE* file, gray* grayrow, int cols, gray maxval, int format )
#else /*__STDC__*/
static int
pgm_readpgmrow( file, grayrow, cols, maxval, format )
    FILE* file;
    gray* grayrow;
    int cols;
    gray maxval;
    int format;
#endif /*__STDC__*/
    {
    register int col, val;
    register gray* gP;

    switch ( format )
	{
	case PGM_FORMAT:
	for ( col = 0, gP = grayrow; col < cols; ++col, ++gP )
	    {
	    val = pbm_getint( file );
	    if ( val == -1 )
		return -1;
	    *gP = val;
	    }
	break;
	
	case RPGM_FORMAT:
	if ( fread( grayrow, 1, cols, file ) != cols )
	    {
	    (void) fprintf( stderr, "%s: EOF / read error\n", progname );
	    return -1;
	    }
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

#if __STDC__
static void
pgm_writepgminit( FILE* file, int cols, int rows, gray maxval, int forceplain )
#else /*__STDC__*/
static void
pgm_writepgminit( file, cols, rows, maxval, forceplain )
    FILE* file;
    int cols, rows;
    gray maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    if ( maxval <= 255 && ! forceplain )
	fprintf(
	    file, "%c%c\n%d %d\n%d\n", PGM_MAGIC1, RPGM_MAGIC2,
	    cols, rows, maxval );
    else
	fprintf(
	    file, "%c%c\n%d %d\n%d\n", PGM_MAGIC1, PGM_MAGIC2,
	    cols, rows, maxval );
    }

static void
putus( n, file )
    unsigned short n;
    FILE* file;
    {
    if ( n >= 10 )
	putus( n / 10, file );
    putc( n % 10 + '0', file );
    }

static int
pgm_writepgmrowraw( file, grayrow, cols, maxval )
    FILE* file;
    gray* grayrow;
    int cols;
    gray maxval;
    {
    if ( fwrite( grayrow, 1, cols, file ) != cols )
	{
	(void) fprintf( stderr, "%s: write error\n", progname );
	return -1;
	}
    return 0;
    }

static int
pgm_writepgmrowplain( file, grayrow, cols, maxval )
    FILE* file;
    gray* grayrow;
    int cols;
    gray maxval;
    {
    register int col, charcount;
    register gray* gP;

    charcount = 0;
    for ( col = 0, gP = grayrow; col < cols; ++col, ++gP )
	{
	if ( charcount >= 65 )
	    {
	    (void) putc( '\n', file );
	    charcount = 0;
	    }
	else if ( charcount > 0 )
	    {
	    (void) putc( ' ', file );
	    ++charcount;
	    }
	putus( (unsigned short) *gP, file );
	charcount += 3;
	}
    if ( charcount > 0 )
	(void) putc( '\n', file );
    return 0;
    }

#if __STDC__
static int
pgm_writepgmrow( FILE* file, gray* grayrow, int cols, gray maxval, int forceplain )
#else /*__STDC__*/
static int
pgm_writepgmrow( file, grayrow, cols, maxval, forceplain )
    FILE* file;
    gray* grayrow;
    int cols;
    gray maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    if ( maxval <= 255 && ! forceplain )
	return pgm_writepgmrowraw( file, grayrow, cols, maxval );
    else
	return pgm_writepgmrowplain( file, grayrow, cols, maxval );
    }

static int
ppm_readppminitrest( file, colsP, rowsP, maxvalP )
    FILE* file;
    int* colsP;
    int* rowsP;
    pixval* maxvalP;
    {
    int maxval;

    /* Read size. */
    *colsP = pbm_getint( file );
    *rowsP = pbm_getint( file );
    if ( *colsP == -1 || *rowsP == -1 )
	return -1;

    /* Read maxval. */
    maxval = pbm_getint( file );
    if ( maxval == -1 )
	return -1;
    if ( maxval > PPM_MAXMAXVAL )
	{
	(void) fprintf( stderr, "%s: maxval is too large\n", progname );
	return -1;
	}
    *maxvalP = maxval;
    return 0;
    }

#if __STDC__
static int
ppm_readppmrow( FILE* file, pixel* pixelrow, int cols, pixval maxval, int format )
#else /*__STDC__*/
static int
ppm_readppmrow( file, pixelrow, cols, maxval, format )
    FILE* file;
    pixel* pixelrow;
    int cols, format;
    pixval maxval;
#endif /*__STDC__*/
    {
    register int col;
    register pixel* pP;
    register int r, g, b;
    gray* grayrow;
    register gray* gP;

    switch ( format )
	{
	case PPM_FORMAT:
	for ( col = 0, pP = pixelrow; col < cols; ++col, ++pP )
	    {
	    r = pbm_getint( file );
	    g = pbm_getint( file );
	    b = pbm_getint( file );
	    if ( r == -1 || g == -1 || b == -1 )
		return -1;
	    PPM_ASSIGN( *pP, r, g, b );
	    }
	break;

	case RPPM_FORMAT:
	grayrow = pgm_allocrow( 3 * cols );
	if ( grayrow == (gray*) 0 )
	    return -1;
	if ( fread( grayrow, 1, 3 * cols, file ) != 3 * cols )
	    {
	    (void) fprintf( stderr, "%s: EOF / read error\n", progname );
	    return -1;
	    }
	for ( col = 0, gP = grayrow, pP = pixelrow; col < cols; ++col, ++pP )
	    {
	    r = *gP++;
	    g = *gP++;
	    b = *gP++;
	    PPM_ASSIGN( *pP, r, g, b );
	    }
	pgm_freerow( grayrow );
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

#if __STDC__
static void
ppm_writeppminit( FILE* file, int cols, int rows, pixval maxval, int forceplain )
#else /*__STDC__*/
static void
ppm_writeppminit( file, cols, rows, maxval, forceplain )
    FILE* file;
    int cols, rows;
    pixval maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    if ( maxval <= 255 && ! forceplain )
	fprintf(
	    file, "%c%c\n%d %d\n%d\n", PPM_MAGIC1, RPPM_MAGIC2,
	    cols, rows, maxval );
    else
	fprintf(
	    file, "%c%c\n%d %d\n%d\n", PPM_MAGIC1, PPM_MAGIC2,
	    cols, rows, maxval );
    }

static int
ppm_writeppmrowraw( file, pixelrow, cols, maxval )
    FILE* file;
    pixel* pixelrow;
    int cols;
    pixval maxval;
    {
    register int col;
    register pixel* pP;
    gray* grayrow;
    register gray* gP;

    grayrow = pgm_allocrow( 3 * cols );
    if ( grayrow == (gray*) 0 )
	return -1;
    for ( col = 0, pP = pixelrow, gP = grayrow; col < cols; ++col, ++pP )
	{
	*gP++ = PPM_GETR( *pP );
	*gP++ = PPM_GETG( *pP );
	*gP++ = PPM_GETB( *pP );
        }
    if ( fwrite( grayrow, 1, 3 * cols, file ) != 3 * cols )
	{
	(void) fprintf( stderr, "%s: write error\n", progname );
	return -1;
	}
    pgm_freerow( grayrow );
    return 0;
    }

static int
ppm_writeppmrowplain( file, pixelrow, cols, maxval )
    FILE* file;
    pixel* pixelrow;
    int cols;
    pixval maxval;
    {
    register int col, charcount;
    register pixel* pP;
    register pixval val;

    charcount = 0;
    for ( col = 0, pP = pixelrow; col < cols; ++col, ++pP )
	{
	if ( charcount >= 65 )
	    {
	    (void) putc( '\n', file );
	    charcount = 0;
	    }
	else if ( charcount > 0 )
	    {
	    (void) putc( ' ', file );
	    (void) putc( ' ', file );
	    charcount += 2;
	    }
	val = PPM_GETR( *pP );
	putus( val, file );
	(void) putc( ' ', file );
	val = PPM_GETG( *pP );
	putus( val, file );
	(void) putc( ' ', file );
	val = PPM_GETB( *pP );
	putus( val, file );
	charcount += 11;
	}
    if ( charcount > 0 )
	(void) putc( '\n', file );
    return 0;
    }

#if __STDC__
static int
ppm_writeppmrow( FILE* file, pixel* pixelrow, int cols, pixval maxval, int forceplain )
#else /*__STDC__*/
static int
ppm_writeppmrow( file, pixelrow, cols, maxval, forceplain )
    FILE* file;
    pixel* pixelrow;
    int cols;
    pixval maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    if ( maxval <= 255 && ! forceplain )
	return ppm_writeppmrowraw( file, pixelrow, cols, maxval );
    else
	return ppm_writeppmrowplain( file, pixelrow, cols, maxval );
    }

void
pnm_init2( pn )
    char* pn;
    {
    /* Save program name. */
    progname = pn;
    }

xelval pnm_pbmmaxval = 1;

int
pnm_readpnminit( file, colsP, rowsP, maxvalP, formatP )
    FILE* file;
    int* colsP;
    int* rowsP;
    int* formatP;
    xelval* maxvalP;
    {
    gray gmaxval;

    /* Check magic number. */
    *formatP = pbm_readmagicnumber( file );
    if ( *formatP == -1 )
	return -1;
    switch ( PNM_FORMAT_TYPE(*formatP) )
	{
	case PPM_TYPE:
	if ( ppm_readppminitrest( file, colsP, rowsP, (pixval*) maxvalP ) < 0 )
	    return -1;
	break;

	case PGM_TYPE:
	if ( pgm_readpgminitrest( file, colsP, rowsP, &gmaxval ) < 0 )
	    return -1;
	*maxvalP = (xelval) gmaxval;
	break;

	case PBM_TYPE:
	if ( pbm_readpbminitrest( file, colsP, rowsP ) < 0 )
	    return -1;
	*maxvalP = pnm_pbmmaxval;
	break;

	default:
	(void) fprintf(
	    stderr, "%s: bad magic number - not a ppm, pgm, or pbm file\n",
	    progname );
	return -1;
	}
    return 0;
    }

#if __STDC__
int
pnm_readpnmrow( FILE* file, xel* xelrow, int cols, xelval maxval, int format )
#else /*__STDC__*/
int
pnm_readpnmrow( file, xelrow, cols, maxval, format )
    FILE* file;
    xel* xelrow;
    xelval maxval;
    int cols, format;
#endif /*__STDC__*/
    {
    register int col;
    register xel* xP;
    gray* grayrow;
    register gray* gP;
    bit* bitrow;
    register bit* bP;

    switch ( PNM_FORMAT_TYPE(format) )
	{
	case PPM_TYPE:
	if ( ppm_readppmrow( file, (pixel*) xelrow, cols, (pixval) maxval, format ) < 0 )
	    return -1;
	break;

	case PGM_TYPE:
	grayrow = pgm_allocrow( cols );
	if ( grayrow == (gray*) 0 )
	    return -1;
	if ( pgm_readpgmrow( file, grayrow, cols, (gray) maxval, format ) < 0 )
	    return -1;
	for ( col = 0, xP = xelrow, gP = grayrow; col < cols; ++col, ++xP, ++gP )
	    PNM_ASSIGN1( *xP, *gP );
	pgm_freerow( grayrow );
	break;

	case PBM_TYPE:
	bitrow = pbm_allocrow( cols );
	if ( bitrow == (bit*) 0 )
	    return -1;
	if ( pbm_readpbmrow( file, bitrow, cols, format ) < 0 )
	    {
	    pbm_freerow( bitrow );
	    return -1;
	    }
	for ( col = 0, xP = xelrow, bP = bitrow; col < cols; ++col, ++xP, ++bP )
	    PNM_ASSIGN1( *xP, *bP == PBM_BLACK ? 0: pnm_pbmmaxval );
	pbm_freerow( bitrow );
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

xel**
pnm_readpnm( file, colsP, rowsP, maxvalP, formatP )
    FILE* file;
    int* colsP;
    int* rowsP;
    int* formatP;
    xelval* maxvalP;
    {
    xel** xels;
    int row;

    if ( pnm_readpnminit( file, colsP, rowsP, maxvalP, formatP ) < 0 )
	return (xel**) 0;

    xels = pnm_allocarray( *colsP, *rowsP );
    if ( xels == (xel**) 0 )
	return (xel**) 0;

    for ( row = 0; row < *rowsP; ++row )
	if ( pnm_readpnmrow( file, xels[row], *colsP, *maxvalP, *formatP ) < 0 )
	    {
	    pnm_freearray( xels, *rowsP );
	    return (xel**) 0;
	    }

    return xels;
    }

#if __STDC__
int
pnm_writepnminit( FILE* file, int cols, int rows, xelval maxval, int format, int forceplain )
#else /*__STDC__*/
int
pnm_writepnminit( file, cols, rows, maxval, format, forceplain )
    FILE* file;
    int cols, rows, format;
    xelval maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    switch ( PNM_FORMAT_TYPE(format) )
	{
	case PPM_TYPE:
	ppm_writeppminit( file, cols, rows, (pixval) maxval, forceplain );
	break;

	case PGM_TYPE:
	pgm_writepgminit( file, cols, rows, (gray) maxval, forceplain );
	break;

	case PBM_TYPE:
	pbm_writepbminit( file, cols, rows, forceplain );
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

#if __STDC__
int
pnm_writepnmrow( FILE* file, xel* xelrow, int cols, xelval maxval, int format, int forceplain )
#else /*__STDC__*/
int
pnm_writepnmrow( file, xelrow, cols, maxval, format, forceplain )
    FILE* file;
    xel* xelrow;
    int cols, format;
    xelval maxval;
    int forceplain;
#endif /*__STDC__*/
    {
    register int col;
    register xel* xP;
    gray* grayrow;
    register gray* gP;
    bit* bitrow;
    register bit* bP;

    switch ( PNM_FORMAT_TYPE(format) )
	{
	case PPM_TYPE:
	if ( ppm_writeppmrow( file, (pixel*) xelrow, cols, (pixval) maxval, forceplain ) < 0 )
	    return -1;
	break;

	case PGM_TYPE:
	grayrow = pgm_allocrow( cols );
	if ( grayrow == (gray*) 0 )
	    return -1;
	for ( col = 0, gP = grayrow, xP = xelrow; col < cols; ++col, ++gP, ++xP )
	    *gP = PNM_GET1( *xP );
	if ( pgm_writepgmrow( file, grayrow, cols, (gray) maxval, forceplain ) < 0 )
	    {
	    pgm_freerow( grayrow );
	    return -1;
	    }
	pgm_freerow( grayrow );
	break;

	case PBM_TYPE:
	bitrow = pbm_allocrow( cols );
	if ( bitrow == (bit*) 0 )
	    return -1;
	for ( col = 0, bP = bitrow, xP = xelrow; col < cols; ++col, ++bP, ++xP )
	    *bP = PNM_GET1( *xP ) == 0 ? PBM_BLACK : PBM_WHITE;
	pbm_writepbmrow( file, bitrow, cols, forceplain );
	pbm_freerow( bitrow );
	break;

	default:
	(void) fprintf( stderr, "%s: can't happen\n", progname );
	return -1;
	}
    return 0;
    }

#if __STDC__
int
pnm_writepnm( FILE* file, xel** xels, int cols, int rows, xelval maxval, int format, int forceplain )
#else /*__STDC__*/
int
pnm_writepnm( file, xels, cols, rows, maxval, format, forceplain )
    FILE* file;
    xel** xels;
    xelval maxval;
    int cols, rows, format;
    int forceplain;
#endif /*__STDC__*/
    {
    int row;

    if ( pnm_writepnminit( file, cols, rows, maxval, format, forceplain ) < 0 )
	return -1;

    for ( row = 0; row < rows; ++row )
	if ( pnm_writepnmrow( file, xels[row], cols, maxval, format, forceplain ) < 0 )
	    return -1;
    return 0;
    }


/* Colormap stuff. */

#define HASH_SIZE 20023

#define ppm_hashpixel(p) ( ( ( (long) PPM_GETR(p) * 33023 + (long) PPM_GETG(p) * 30013 + (long) PPM_GETB(p) * 27011 ) & 0x7fffffff ) % HASH_SIZE )

colorhist_vector
ppm_computecolorhist( pixels, cols, rows, maxcolors, colorsP )
    pixel** pixels;
    int cols, rows, maxcolors;
    int* colorsP;
    {
    colorhash_table cht;
    colorhist_vector chv;

    cht = ppm_computecolorhash( pixels, cols, rows, maxcolors, colorsP );
    if ( cht == (colorhash_table) 0 )
	return (colorhist_vector) 0;
    chv = ppm_colorhashtocolorhist( cht, maxcolors );
    ppm_freecolorhash( cht );
    return chv;
    }

void
ppm_addtocolorhist( chv, colorsP, maxcolors, colorP, value, position )
    colorhist_vector chv;
    pixel* colorP;
    int* colorsP;
    int maxcolors, value, position;
    {
    int i, j;

    /* Search colorhist for the color. */
    for ( i = 0; i < *colorsP; ++i )
	if ( PPM_EQUAL( chv[i].color, *colorP ) )
	    {
	    /* Found it - move to new slot. */
	    if ( position > i )
		{
		for ( j = i; j < position; ++j )
		    chv[j] = chv[j + 1];
		}
	    else if ( position < i )
		{
		for ( j = i; j > position; --j )
		    chv[j] = chv[j - 1];
		}
	    chv[position].color = *colorP;
	    chv[position].value = value;
	    return;
	    }
    if ( *colorsP < maxcolors )
	{
	/* Didn't find it, but there's room to add it; so do so. */
	for ( i = *colorsP; i > position; --i )
	    chv[i] = chv[i - 1];
	chv[position].color = *colorP;
	chv[position].value = value;
	++(*colorsP);
	}
    }

colorhash_table
ppm_computecolorhash( pixels, cols, rows, maxcolors, colorsP )
    pixel** pixels;
    int cols, rows, maxcolors;
    int* colorsP;
    {
    colorhash_table cht;
    register pixel* pP;
    colorhist_list chl;
    int col, row, hash;

    cht = ppm_alloccolorhash( );
    if ( cht == (colorhash_table) 0 )
	return (colorhash_table) 0;
    *colorsP = 0;

    /* Go through the entire image, building a hash table of colors. */
    for ( row = 0; row < rows; ++row )
	for ( col = 0, pP = pixels[row]; col < cols; ++col, ++pP )
	    {
	    hash = ppm_hashpixel( *pP );
	    for ( chl = cht[hash]; chl != (colorhist_list) 0; chl = chl->next )
		if ( PPM_EQUAL( chl->ch.color, *pP ) )
		    break;
	    if ( chl != (colorhist_list) 0 )
		++(chl->ch.value);
	    else
		{
		if ( ++(*colorsP) > maxcolors )
		    {
		    ppm_freecolorhash( cht );
		    return (colorhash_table) 0;
		    }
		chl = (colorhist_list) malloc( sizeof(struct colorhist_list_item) );
		if ( chl == 0 )
		    {
		    (void) fprintf(
			stderr, "%s: out of memory computing hash table\n",
			progname );
		    ppm_freecolorhash( cht );
		    return (colorhash_table) 0;
		    }
		chl->ch.color = *pP;
		chl->ch.value = 1;
		chl->next = cht[hash];
		cht[hash] = chl;
		}
	    }
    
    return cht;
    }

colorhash_table
ppm_alloccolorhash( )
    {
    colorhash_table cht;
    int i;

    cht = (colorhash_table) malloc( HASH_SIZE * sizeof(colorhist_list) );
    if ( cht == 0 )
	{
	(void) fprintf(
	    stderr, "%s: out of memory allocating hash table\n", progname );
	return (colorhash_table) 0;
	}

    for ( i = 0; i < HASH_SIZE; ++i )
	cht[i] = (colorhist_list) 0;

    return cht;
    }

int
ppm_addtocolorhash( cht, colorP, value )
    colorhash_table cht;
    pixel* colorP;
    int value;
    {
    register int hash;
    register colorhist_list chl;

    chl = (colorhist_list) malloc( sizeof(struct colorhist_list_item) );
    if ( chl == 0 )
	return -1;
    hash = ppm_hashpixel( *colorP );
    chl->ch.color = *colorP;
    chl->ch.value = value;
    chl->next = cht[hash];
    cht[hash] = chl;
    return 0;
    }

colorhist_vector
ppm_colorhashtocolorhist( cht, maxcolors )
    colorhash_table cht;
    int maxcolors;
    {
    colorhist_vector chv;
    colorhist_list chl;
    int i, j;

    /* Now collate the hash table into a simple colorhist array. */
    chv = (colorhist_vector) malloc( maxcolors * sizeof(struct colorhist_item) );
    /* (Leave room for expansion by caller.) */
    if ( chv == (colorhist_vector) 0 )
	{
	(void) fprintf(
	    stderr, "%s: out of memory generating histogram\n", progname );
	return (colorhist_vector) 0;
	}

    /* Loop through the hash table. */
    j = 0;
    for ( i = 0; i < HASH_SIZE; ++i )
	for ( chl = cht[i]; chl != (colorhist_list) 0; chl = chl->next )
	    {
	    /* Add the new entry. */
	    chv[j] = chl->ch;
	    ++j;
	    }

    /* All done. */
    return chv;
    }

colorhash_table
ppm_colorhisttocolorhash( chv, colors )
    colorhist_vector chv;
    int colors;
    {
    colorhash_table cht;
    int i, hash;
    pixel color;
    colorhist_list chl;

    cht = ppm_alloccolorhash( );
    if ( cht == (colorhash_table) 0 )
	return (colorhash_table) 0;

    for ( i = 0; i < colors; ++i )
	{
	color = chv[i].color;
	hash = ppm_hashpixel( color );
	for ( chl = cht[hash]; chl != (colorhist_list) 0; chl = chl->next )
	    if ( PPM_EQUAL( chl->ch.color, color ) )
		{
		(void) fprintf(
		    stderr, "%s: same color found twice - %d %d %d\n", progname,
		    PPM_GETR(color), PPM_GETG(color), PPM_GETB(color) );
		ppm_freecolorhash( cht );
		return (colorhash_table) 0;
		}
	chl = (colorhist_list) malloc( sizeof(struct colorhist_list_item) );
	if ( chl == (colorhist_list) 0 )
	    {
	    (void) fprintf( stderr, "%s: out of memory\n", progname );
	    ppm_freecolorhash( cht );
	    return (colorhash_table) 0;
	    }
	chl->ch.color = color;
	chl->ch.value = i;
	chl->next = cht[hash];
	cht[hash] = chl;
	}

    return cht;
    }

int
ppm_lookupcolor( cht, colorP )
    colorhash_table cht;
    pixel* colorP;
    {
    int hash;
    colorhist_list chl;

    hash = ppm_hashpixel( *colorP );
    for ( chl = cht[hash]; chl != (colorhist_list) 0; chl = chl->next )
	if ( PPM_EQUAL( chl->ch.color, *colorP ) )
	    return chl->ch.value;

    return -1;
    }

void
ppm_freecolorhist( chv )
    colorhist_vector chv;
    {
    free( (char*) chv );
    }

void
ppm_freecolorhash( cht )
    colorhash_table cht;
    {
    int i;
    colorhist_list chl, chlnext;

    for ( i = 0; i < HASH_SIZE; ++i )
	for ( chl = cht[i]; chl != (colorhist_list) 0; chl = chlnext )
	    {
	    chlnext = chl->next;
	    free( (char*) chl );
	    }
    free( (char*) cht );
    }