xref: /plan9/sys/src/cmd/gs/src/sbhc.h (revision 593dc095aefb2a85c828727bbfa9da139a49bdf4)
1 /* Copyright (C) 1994 Aladdin Enterprises.  All rights reserved.
2 
3   This software is provided AS-IS with no warranty, either express or
4   implied.
5 
6   This software is distributed under license and may not be copied,
7   modified or distributed except as expressly authorized under the terms
8   of the license contained in the file LICENSE in this distribution.
9 
10   For more information about licensing, please refer to
11   http://www.ghostscript.com/licensing/. For information on
12   commercial licensing, go to http://www.artifex.com/licensing/ or
13   contact Artifex Software, Inc., 101 Lucas Valley Road #110,
14   San Rafael, CA  94903, U.S.A., +1(415)492-9861.
15 */
16 
17 /* $Id: sbhc.h,v 1.4 2002/02/21 22:24:53 giles Exp $ */
18 /* Definitions for BoundedHuffman filters */
19 /* Requires strimpl.h */
20 
21 #ifndef sbhc_INCLUDED
22 #  define sbhc_INCLUDED
23 
24 #include "shc.h"
25 
26 /*
27  * The BoundedHuffman filters extend the basic Huffman coding model by
28  * providing the ability to encode runs of zeros as a single data item,
29  * and by providing an end-of-data (EOD) marker.
30  */
31 #define max_zero_run 100
32 
33 /* Common state */
34 #define stream_BHC_state_common\
35 	stream_hc_state_common;\
36 	hc_definition definition;\
37 		/* The client sets the following before initialization. */\
38 	bool EndOfData;\
39 	uint EncodeZeroRuns;\
40 		/* The following are updated dynamically. */\
41 	int zeros		/* # of zeros scanned or left to output */
42 typedef struct stream_BHC_state_s {
43     stream_BHC_state_common;
44 } stream_BHC_state;
45 
46 /* BoundedHuffmanEncode */
47 typedef struct stream_BHCE_state_s {
48     stream_BHC_state_common;
49     hce_table encode;
50 } stream_BHCE_state;
51 
52 #define private_st_BHCE_state()	/* in sbhc.c */\
53   gs_private_st_ptrs3(st_BHCE_state, stream_BHCE_state,\
54     "BoundedHuffmanEncode state", bhce_enum_ptrs, bhce_reloc_ptrs,\
55     definition.counts, definition.values, encode.codes)
56 extern const stream_template s_BHCE_template;
57 
58 #define s_bhce_init_inline(ss)\
59   (s_hce_init_inline(ss), (ss)->zeros = 0)
60 
61 /* BoundedHuffmanDecode */
62 typedef struct stream_BHCD_state_s {
63     stream_BHC_state_common;
64     hcd_table decode;
65 } stream_BHCD_state;
66 
67 #define private_st_BHCD_state()	/* in sbhc.c */\
68   gs_private_st_ptrs3(st_BHCD_state, stream_BHCD_state,\
69     "BoundedHuffmanDecode state", bhcd_enum_ptrs, bhcd_reloc_ptrs,\
70     definition.counts, definition.values, decode.codes)
71 extern const stream_template s_BHCD_template;
72 
73 #define s_bhcd_init_inline(ss)\
74   (s_hcd_init_inline(ss), (ss)->zeros = 0)
75 
76 /* Declare variables that hold the decoder state. */
77 #define bhcd_declare_state\
78 	hcd_declare_state;\
79 	int zeros
80 
81 /* Load the state from the stream. */
82 /* Free variables: pr, ss, p, rlimit, bits, bits_left, zeros. */
83 #define bhcd_load_state()\
84 	hcd_load_state(), zeros = ss->zeros
85 
86 /* Store the state back in the stream. */
87 /* Free variables: pr, ss, p, bits, bits_left, zeros. */
88 #define bhcd_store_state()\
89 	hcd_store_state(), ss->zeros = zeros
90 
91 #endif /* sbhc_INCLUDED */
92