JasPer  4.0.0
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.
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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_least32_t creg;
94 
95  /* The A register. */
96  uint_least32_t areg;
97 
98  /* The CT register. */
99  uint_least32_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  unsigned 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  bool 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(unsigned 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 static inline void jpc_mqdec_setcurctx(jpc_mqdec_t *dec, unsigned ctxno)
147 {
148  dec->curctx = &dec->ctxs[ctxno];
149 }
150 
151 /* Set the state information for all contexts of a MQ decoder. */
152 void jpc_mqdec_setctxs(const jpc_mqdec_t *dec, unsigned numctxs, const jpc_mqctx_t *ctxs);
153 
154 /******************************************************************************\
155 * Functions/macros for decoding bits.
156 \******************************************************************************/
157 
158 /* Decode a symbol. */
159 #ifdef NDEBUG
160 #define jpc_mqdec_getbit(dec) \
161  jpc_mqdec_getbit_macro(dec)
162 #else
163 #define jpc_mqdec_getbit(dec) \
164  jpc_mqdec_getbit_func(dec)
165 #endif
166 
167 /* Decode a symbol (assuming an unskewed probability distribution). */
168 #ifdef NDEBUG
169 #define jpc_mqdec_getbitnoskew(dec) \
170  jpc_mqdec_getbit_macro(dec)
171 #else
172 #define jpc_mqdec_getbitnoskew(dec) \
173  jpc_mqdec_getbit_func(dec)
174 #endif
175 
176 /******************************************************************************\
177 * Functions/macros for debugging.
178 \******************************************************************************/
179 
180 /* Dump the MQ decoder state for debugging. */
181 void jpc_mqdec_dump(const jpc_mqdec_t *dec);
182 
183 /******************************************************************************\
184 * EVERYTHING BELOW THIS POINT IS IMPLEMENTATION SPECIFIC AND NOT PART OF THE
185 * APPLICATION INTERFACE. DO NOT RELY ON ANY OF THE INTERNAL FUNCTIONS/MACROS
186 * GIVEN BELOW.
187 \******************************************************************************/
188 
189 bool jpc_mqdec_mpsexchrenormd(jpc_mqdec_t *dec);
190 bool jpc_mqdec_lpsexchrenormd(jpc_mqdec_t *dec);
191 
192 JAS_FORCE_INLINE
193 static bool jpc_mqdec_getbit_macro(jpc_mqdec_t *dec)
194 {
195  const jpc_mqstate_t *const state = *dec->curctx;
196 
197  dec->areg -= state->qeval;
198 
199  if (dec->creg >= (uint_least32_t)state->qeval << 16) {
200  dec->creg -= (uint_least32_t)state->qeval << 16;
201  return dec->areg & 0x8000
202  ? state->mps
203  : jpc_mqdec_mpsexchrenormd(dec);
204  } else {
205  return jpc_mqdec_lpsexchrenormd(dec);
206  }
207 }
208 
209 JAS_FORCE_INLINE
210 static bool jpc_mqdec_mpsexchange(uint_least32_t areg, uint_least32_t delta, const jpc_mqstate_t **curctx)
211 {
212  if (areg < delta) {
213  const jpc_mqstate_t *state = *curctx;
214  /* LPS decoded. */
215  *curctx = state->nlps;
216  return !state->mps;
217  } else {
218  const jpc_mqstate_t *state = *curctx;
219  /* MPS decoded. */
220  *curctx = state->nmps;
221  return state->mps;
222  }
223 }
224 
225 JAS_FORCE_INLINE
226 static bool jpc_mqdec_lpsexchange(uint_least32_t *areg_p, uint_least32_t delta, const jpc_mqstate_t **curctx)
227 {
228  if (*areg_p >= delta) {
229  const jpc_mqstate_t *state = *curctx;
230  *areg_p = delta;
231  *curctx = state->nlps;
232  return !state->mps;
233  } else {
234  const jpc_mqstate_t *state = *curctx;
235  *areg_p = delta;
236  *curctx = state->nmps;
237  return state->mps;
238  }
239 }
240 
241 bool jpc_mqdec_getbit_func(jpc_mqdec_t *dec);
242 
243 #endif
I/O stream object.
Definition: jas_stream.h:206
Primitive Types.
I/O Stream Class.