/*
 *		I M O D . C
 *
 *  Modify intensities in a stream of short (16 bit) unsigned integers.
 *
 *  Allows any number of add, subtract, multiply, divide, or
 *  exponentiation operations to be performed on a picture.
 *  Keeps track of and reports clipping.
 *
 *  Author -
 *  	Lee A. Butler
 *	25 October 1990
 *
 *  Source -
 *	SECAD/VLD Computing Consortium, Bldg 394
 *	The U. S. Army Ballistic Research Laboratory
 *	Aberdeen Proving Ground, Maryland  21005-5066
 *  
 *  Copyright Notice -
 *	This software is Copyright (C) 1986 by the United States Army.
 *	All rights reserved.
 */
#ifndef lint
static char RCSid[] = "@(#)$Header$ (BRL)";
#endif

#include <stdio.h>
#include <math.h>
/* #include "externs.h" */

#if !defined(SYSV) && defined(BSD) && BSD < 43
#define	strrchr rindex
#endif

extern int	getopt();
extern char	*optarg;
extern int	optind;
char *progname = "(noname)";

char	*file_name;

char usage[] = "\
Usage: smod {-a add -s sub -m mult -d div -A(abs) -e exp -r root} [file.s]\n";

#define	ADD	1
#define MULT	2
#define	ABS	3
#define	POW	4
#define	BUFLEN	(8192*2)	/* usually 2 pages of memory, 16KB */

int	numop = 0;		/* number of operations */
int	op[256];		/* operations */
double	val[256];		/* arguments to operations */
unsigned short iobuf[BUFLEN];		/* input buffer */
int mapbuf[65536];		/* translation buffer/lookup table */

get_args( argc, argv )
register char **argv;
{
	register int c;
	double	d;

	while ( (c = getopt( argc, argv, "a:s:m:d:Ae:r:" )) != EOF )  {
		switch( c )  {
		case 'a':
			op[ numop ] = ADD;
			val[ numop++ ] = atof(optarg);
			break;
		case 's':
			op[ numop ] = ADD;
			val[ numop++ ] = - atof(optarg);
			break;
		case 'm':
			op[ numop ] = MULT;
			val[ numop++ ] = atof(optarg);
			break;
		case 'd':
			op[ numop ] = MULT;
			d = atof(optarg);
			if( d == 0.0 ) {
				(void)fprintf( stderr, "bwmod: divide by zero!\n" );
				exit( 2 );
			}
			val[ numop++ ] = 1.0 / d;
			break;
		case 'A':
			op[ numop ] = ABS;
			val[ numop++ ] = 0;
			break;
		case 'e':
			op[ numop ] = POW;
			val[ numop++ ] = atof(optarg);
			break;
		case 'r':
			op[ numop ] = POW;
			d = atof(optarg);
			if( d == 0.0 ) {
				(void)fprintf( stderr, "bwmod: zero root!\n" );
				exit( 2 );
			}
			val[ numop++ ] = 1.0 / d;
			break;

		default:		/* '?' */
			return(0);
		}
	}

	if( optind >= argc )  {
		if( isatty((int)fileno(stdin)) )
			return(0);
		file_name = "-";
	} else {
		file_name = argv[optind];
		if( freopen(file_name, "r", stdin) == NULL )  {
			(void)fprintf( stderr,
				"bwmod: cannot open \"%s\" for reading\n",
				file_name );
			return(0);
		}
	}

	if ( argc > ++optind )
		(void)fprintf( stderr, "bwmod: excess argument(s) ignored\n" );

	return(1);		/* OK */
}

void mk_trans_tbl()
{
	register int i, j;
	register double d;

	/* create translation map */
	for (j = 0; j < 65536 ; ++j) {
		d = j;
		for (i=0 ; i < numop ; i++) {
			switch (op[i]) {
			case ADD : d += val[i]; break;
			case MULT: d *= val[i]; break;
			case POW : d = pow( d, val[i]); break;
			case ABS : if (d < 0.0) d = - d; break;
			default  : (void)fprintf(stderr, "%s: error in op\n",
					progname); break;
			}
		}

		if (d > 65535.0)
			mapbuf[j] = 65537;
		else if (d < 0.0)
			mapbuf[j] = -1;
		else
			mapbuf[j] = d + 0.5;
	}
}

int main( argc, argv )
int argc;
char **argv;
{
	register unsigned short *p, *q;
	register unsigned int	n;
	unsigned long clip_high, clip_low;
	char *strrchr();
	
	if (!(progname=strrchr(*argv, '/')))
		progname = *argv;

	if( !get_args( argc, argv ) || isatty(fileno(stdin))
	    || isatty(fileno(stdout)) ) {
		(void)fputs(usage, stderr);
		exit( 1 );
	}

	mk_trans_tbl();

	clip_high = clip_low = 0;

	while ( (n=fread(iobuf, sizeof(*iobuf), BUFLEN, stdin)) > 0) {
		/* translate */
		for (p=iobuf, q= &iobuf[n] ; p < q ; ++p) {
			if (mapbuf[*p] > 65535) { ++clip_high; *p = 65535; }
			else if (mapbuf[*p] < -0) { ++clip_low; *p = 0; }
			else *p = (unsigned short)mapbuf[*p];
		}
		/* output */
		if (fwrite(iobuf, sizeof(*iobuf), n, stdout) != n) {
			(void)fprintf(stderr, "%s: Error writing stdout\n",
				progname);
			exit(-1);
		}
	}

	if( clip_high != 0L || clip_low != 0L ) {
		(void)fprintf( stderr, "%s: clipped %lu high, %lu low\n",
			progname,
			clip_high, clip_low );
	}
	return(0);
}