My Project  2.0.19
jpc_mqdec.h
1 /*
2  * Copyright (c) 1999-2000 Image Power, Inc. and the University of
3  * British Columbia.
4  * Copyright (c) 2001-2003 Michael David Adams.
5  * All rights reserved.
6  */
7 
8 /* __START_OF_JASPER_LICENSE__
9  *
10  * JasPer License Version 2.0
11  *
12  * Copyright (c) 2001-2006 Michael David Adams
13  * Copyright (c) 1999-2000 Image Power, Inc.
14  * Copyright (c) 1999-2000 The University of British Columbia
15  *
16  * All rights reserved.
17  *
18  * Permission is hereby granted, free of charge, to any person (the
19  * "User") obtaining a copy of this software and associated documentation
20  * files (the "Software"), to deal in the Software without restriction,
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22  * publish, distribute, and/or sell copies of the Software, and to permit
23  * persons to whom the Software is furnished to do so, subject to the
24  * following conditions:
25  *
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27  * includes the disclaimer below) shall be included in all copies or
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31  * promote products derived from the Software without specific prior
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33  *
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58  * RISK ACTIVITIES"). THE COPYRIGHT HOLDERS SPECIFICALLY DISCLAIM ANY
59  * EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR HIGH RISK ACTIVITIES.
60  *
61  * __END_OF_JASPER_LICENSE__
62  */
63 
64 /*
65  * MQ Arithmetic Decoder
66  *
67  * $Id$
68  */
69 
70 #ifndef JPC_MQDEC_H
71 #define JPC_MQDEC_H
72 
73 /******************************************************************************\
74 * Includes.
75 \******************************************************************************/
76 
77 #include "jasper/jas_types.h"
78 #include "jasper/jas_stream.h"
79 
80 #include "jpc_mqcod.h"
81 
82 #include <stdio.h>
83 
84 /******************************************************************************\
85 * Types.
86 \******************************************************************************/
87 
88 /* MQ arithmetic decoder. */
89 
90 typedef struct {
91 
92  /* The C register. */
93  uint_fast32_t creg;
94 
95  /* The A register. */
96  uint_fast32_t areg;
97 
98  /* The CT register. */
99  uint_fast32_t ctreg;
100 
101  /* The current context. */
102  const jpc_mqstate_t **curctx;
103 
104  /* The per-context information. */
105  const jpc_mqstate_t **ctxs;
106 
107  /* The maximum number of contexts. */
108  int maxctxs;
109 
110  /* The stream from which to read data. */
111  jas_stream_t *in;
112 
113  /* The last character read. */
114  jas_uchar inbuffer;
115 
116  /* The EOF indicator. */
117  int eof;
118 
119 } jpc_mqdec_t;
120 
121 /******************************************************************************\
122 * Functions/macros for construction and destruction.
123 \******************************************************************************/
124 
125 /* Create a MQ decoder. */
126 jpc_mqdec_t *jpc_mqdec_create(int maxctxs, jas_stream_t *in);
127 
128 /* Destroy a MQ decoder. */
129 void jpc_mqdec_destroy(jpc_mqdec_t *dec);
130 
131 /******************************************************************************\
132 * Functions/macros for initialization.
133 \******************************************************************************/
134 
135 /* Set the input stream associated with a MQ decoder. */
136 void jpc_mqdec_setinput(jpc_mqdec_t *dec, jas_stream_t *in);
137 
138 /* Initialize a MQ decoder. */
139 void jpc_mqdec_init(jpc_mqdec_t *dec);
140 
141 /******************************************************************************\
142 * Functions/macros for manipulating contexts.
143 \******************************************************************************/
144 
145 /* Set the current context for a MQ decoder. */
146 #define jpc_mqdec_setcurctx(dec, ctxno) \
147  ((mqdec)->curctx = &(mqdec)->ctxs[ctxno]);
148 
149 /* Set the state information for a particular context of a MQ decoder. */
150 void jpc_mqdec_setctx(jpc_mqdec_t *dec, int ctxno, const jpc_mqctx_t *ctx);
151 
152 /* Set the state information for all contexts of a MQ decoder. */
153 void jpc_mqdec_setctxs(const jpc_mqdec_t *dec, int numctxs, const jpc_mqctx_t *ctxs);
154 
155 /******************************************************************************\
156 * Functions/macros for decoding bits.
157 \******************************************************************************/
158 
159 /* Decode a symbol. */
160 #if !defined(DEBUG)
161 #define jpc_mqdec_getbit(dec) \
162  jpc_mqdec_getbit_macro(dec)
163 #else
164 #define jpc_mqdec_getbit(dec) \
165  jpc_mqdec_getbit_func(dec)
166 #endif
167 
168 /* Decode a symbol (assuming an unskewed probability distribution). */
169 #if !defined(DEBUG)
170 #define jpc_mqdec_getbitnoskew(dec) \
171  jpc_mqdec_getbit_macro(dec)
172 #else
173 #define jpc_mqdec_getbitnoskew(dec) \
174  jpc_mqdec_getbit_func(dec)
175 #endif
176 
177 /******************************************************************************\
178 * Functions/macros for debugging.
179 \******************************************************************************/
180 
181 /* Dump the MQ decoder state for debugging. */
182 void jpc_mqdec_dump(const jpc_mqdec_t *dec, FILE *out);
183 
184 /******************************************************************************\
185 * EVERYTHING BELOW THIS POINT IS IMPLEMENTATION SPECIFIC AND NOT PART OF THE
186 * APPLICATION INTERFACE. DO NOT RELY ON ANY OF THE INTERNAL FUNCTIONS/MACROS
187 * GIVEN BELOW.
188 \******************************************************************************/
189 
190 #define jpc_mqdec_getbit_macro(dec) \
191  ((((dec)->areg -= (*(dec)->curctx)->qeval), \
192  (dec)->creg >> 16 >= (*(dec)->curctx)->qeval) ? \
193  ((((dec)->creg -= (*(dec)->curctx)->qeval << 16), \
194  (dec)->areg & 0x8000) ? (*(dec)->curctx)->mps : \
195  jpc_mqdec_mpsexchrenormd(dec)) : \
196  jpc_mqdec_lpsexchrenormd(dec))
197 
198 #define jpc_mqdec_mpsexchange(areg, delta, curctx, bit) \
199 { \
200  if ((areg) < (delta)) { \
201  register const jpc_mqstate_t *state = *(curctx); \
202  /* LPS decoded. */ \
203  (bit) = state->mps ^ 1; \
204  *(curctx) = state->nlps; \
205  } else { \
206  register const jpc_mqstate_t *state = *(curctx); \
207  /* MPS decoded. */ \
208  (bit) = state->mps; \
209  *(curctx) = state->nmps; \
210  } \
211 }
212 
213 #define jpc_mqdec_lpsexchange(areg, delta, curctx, bit) \
214 { \
215  if ((areg) >= (delta)) { \
216  register const jpc_mqstate_t *state = *(curctx); \
217  (areg) = (delta); \
218  (bit) = state->mps ^ 1; \
219  *(curctx) = state->nlps; \
220  } else { \
221  register const jpc_mqstate_t *state = *(curctx); \
222  (areg) = (delta); \
223  (bit) = state->mps; \
224  *(curctx) = state->nmps; \
225  } \
226 }
227 
228 #define jpc_mqdec_renormd(areg, creg, ctreg, in, eof, inbuf) \
229 { \
230  do { \
231  if (!(ctreg)) { \
232  jpc_mqdec_bytein2(creg, ctreg, in, eof, inbuf); \
233  } \
234  (areg) <<= 1; \
235  (creg) <<= 1; \
236  --(ctreg); \
237  } while (!((areg) & 0x8000)); \
238 }
239 
240 #define jpc_mqdec_bytein2(creg, ctreg, in, eof, inbuf) \
241 { \
242  int c; \
243  unsigned char prevbuf; \
244  if (!(eof)) { \
245  if ((c = jas_stream_getc(in)) == EOF) { \
246  (eof) = 1; \
247  c = 0xff; \
248  } \
249  prevbuf = (inbuf); \
250  (inbuf) = c; \
251  if (prevbuf == 0xff) { \
252  if (c > 0x8f) { \
253  (creg) += 0xff00; \
254  (ctreg) = 8; \
255  } else { \
256  (creg) += c << 9; \
257  (ctreg) = 7; \
258  } \
259  } else { \
260  (creg) += c << 8; \
261  (ctreg) = 8; \
262  } \
263  } else { \
264  (creg) += 0xff00; \
265  (ctreg) = 8; \
266  } \
267 }
268 
269 int jpc_mqdec_getbit_func(jpc_mqdec_t *dec);
270 int jpc_mqdec_mpsexchrenormd(jpc_mqdec_t *dec);
271 int jpc_mqdec_lpsexchrenormd(jpc_mqdec_t *dec);
272 
273 #endif