/* Copyright (C) 1994, 1995, 1999 Aladdin Enterprises.  All rights reserved.
  
  This software is provided AS-IS with no warranty, either express or
  implied.
  
  This software is distributed under license and may not be copied,
  modified or distributed except as expressly authorized under the terms
  of the license contained in the file LICENSE in this distribution.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/* $Id: spdiffx.h,v 1.4 2002/02/21 22:24:54 giles Exp $ */
/* Definitions for PixelDifference filters */
/* Requires strimpl.h */

#ifndef spdiffx_INCLUDED
#  define spdiffx_INCLUDED

/*
 * Define the maximum value for Colors.  This must be at least 4, but can
 * be arbitrarily large: the only cost is a larger stream state structure.
 */
#define s_PDiff_max_Colors 16

/* PixelDifferenceDecode / PixelDifferenceEncode */
typedef struct stream_PDiff_state_s {
    stream_state_common;
    /* The client sets the following before initialization. */
    int Colors;			/* # of colors, 1..s_PDiff_max_Colors */
    int BitsPerComponent;	/* 1, 2, 4, 8 */
    int Columns;
    /* The init procedure computes the following. */
    uint row_count;		/* # of bytes per row */
    byte end_mask;		/* mask for left-over bits in last byte */
    int case_index;		/* switch index for case dispatch */
    /* The following are updated dynamically. */
    uint row_left;		/* # of bytes left in row */
    byte prev[s_PDiff_max_Colors];	/* previous sample */
} stream_PDiff_state;

#define private_st_PDiff_state()	/* in spdiff.c */\
  gs_private_st_simple(st_PDiff_state, stream_PDiff_state,\
    "PixelDifferenceEncode/Decode state")
#define s_PDiff_set_defaults_inline(ss)\
  ((ss)->Colors = 1, (ss)->BitsPerComponent = 8, (ss)->Columns = 1)
extern const stream_template s_PDiffD_template;
extern const stream_template s_PDiffE_template;

#endif /* spdiffx_INCLUDED */
