/* Copyright (C) 1996, 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: spngpx.h,v 1.4 2002/02/21 22:24:54 giles Exp $ */
/* Definitions for PNGPredictor filters */
/* Requires strimpl.h */

#ifndef spngpx_INCLUDED
#  define spngpx_INCLUDED

/* PNGPredictorDecode / PNGPredictorEncode */
typedef struct stream_PNGP_state_s {
    stream_state_common;
    /* The client sets the following before initialization. */
    int Colors;			/* # of colors, 1..16 */
    int BitsPerComponent;	/* 1, 2, 4, 8, 16 */
    uint Columns;		/* >0 */
    int Predictor;		/* 10-15, only relevant for Encode */
    /* 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 bpp;			/* bytes per pixel */
    byte *prev_row;		/* previous row */
    int case_index;		/* switch index for case dispatch, */
				/* set dynamically when decoding */
    /* The following are updated dynamically. */
    long row_left;		/* # of bytes left in row */
    byte prev[32];		/* previous samples */
} stream_PNGP_state;

#define private_st_PNGP_state()	/* in sPNGP.c */\
  gs_private_st_ptrs1(st_PNGP_state, stream_PNGP_state,\
    "PNGPredictorEncode/Decode state", pngp_enum_ptrs, pngp_reloc_ptrs,\
    prev_row)
#define s_PNGP_set_defaults_inline(ss)\
  ((ss)->Colors = 1, (ss)->BitsPerComponent = 8, (ss)->Columns = 1,\
   (ss)->Predictor = 15,\
		/* Clear pointers */\
   (ss)->prev_row = 0)
extern const stream_template s_PNGPD_template;
extern const stream_template s_PNGPE_template;

#endif /* spngpx_INCLUDED */
