2 * Copyright (c) 2002-2007, Communications and Remote Sensing Laboratory, Universite catholique de Louvain (UCL), Belgium
3 * Copyright (c) 2002-2007, Professor Benoit Macq
4 * Copyright (c) 2001-2003, David Janssens
5 * Copyright (c) 2002-2003, Yannick Verschueren
6 * Copyright (c) 2003-2007, Francois-Olivier Devaux and Antonin Descampe
7 * Copyright (c) 2005, Herve Drolon, FreeImage Team
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36 @brief Implementation of an MQ-Coder (MQC)
38 The functions in MQC.C have for goal to realize the MQ-coder operations. The functions
39 in MQC.C are used by some function in T1.C.
42 /** @defgroup MQC MQC - Implementation of an MQ-Coder */
46 This struct defines the state of a context.
48 typedef struct opj_mqc_state {
49 /** the probability of the Least Probable Symbol (0.75->0x8000, 1.5->0xffff) */
51 /** the Most Probable Symbol (0 or 1) */
53 /** next state if the next encoded symbol is the MPS */
54 struct opj_mqc_state *nmps;
55 /** next state if the next encoded symbol is the LPS */
56 struct opj_mqc_state *nlps;
59 #define MQC_NUMCTXS 19
64 typedef struct opj_mqc {
71 opj_mqc_state_t *ctxs[MQC_NUMCTXS];
72 opj_mqc_state_t **curctx;
74 unsigned char *buffer;
78 /** @name Exported functions */
80 /* ----------------------------------------------------------------------- */
82 Create a new MQC handle
83 @return Returns a new MQC handle if successful, returns NULL otherwise
85 opj_mqc_t* mqc_create(void);
87 Destroy a previously created MQC handle
88 @param mqc MQC handle to destroy
90 void mqc_destroy(opj_mqc_t *mqc);
92 Return the number of bytes written/read since initialisation
94 @return Returns the number of bytes already encoded
96 int mqc_numbytes(opj_mqc_t *mqc);
98 Reset the states of all the context of the coder/decoder
99 (each context is set to a state where 0 and 1 are more or less equiprobable)
100 @param mqc MQC handle
102 void mqc_resetstates(opj_mqc_t *mqc);
104 Set the state of a particular context
105 @param mqc MQC handle
106 @param ctxno Number that identifies the context
107 @param msb The MSB of the new state of the context
108 @param prob Number that identifies the probability of the symbols for the new state of the context
110 void mqc_setstate(opj_mqc_t *mqc, int ctxno, int msb, int prob);
112 Initialize the encoder
113 @param mqc MQC handle
114 @param bp Pointer to the start of the buffer where the bytes will be written
116 void mqc_init_enc(opj_mqc_t *mqc, unsigned char *bp);
118 Set the current context used for coding/decoding
119 @param mqc MQC handle
120 @param ctxno Number that identifies the context
122 #define mqc_setcurctx(mqc, ctxno) (mqc)->curctx = &(mqc)->ctxs[(int)(ctxno)]
124 Encode a symbol using the MQ-coder
125 @param mqc MQC handle
126 @param d The symbol to be encoded (0 or 1)
128 void mqc_encode(opj_mqc_t *mqc, int d);
130 Flush the encoder, so that all remaining data is written
131 @param mqc MQC handle
133 void mqc_flush(opj_mqc_t *mqc);
135 BYPASS mode switch, initialization operation.
137 <h2>Not fully implemented and tested !!</h2>
138 @param mqc MQC handle
140 void mqc_bypass_init_enc(opj_mqc_t *mqc);
142 BYPASS mode switch, coding operation.
144 <h2>Not fully implemented and tested !!</h2>
145 @param mqc MQC handle
146 @param d The symbol to be encoded (0 or 1)
148 void mqc_bypass_enc(opj_mqc_t *mqc, int d);
150 BYPASS mode switch, flush operation
151 <h2>Not fully implemented and tested !!</h2>
152 @param mqc MQC handle
153 @return Returns 1 (always)
155 int mqc_bypass_flush_enc(opj_mqc_t *mqc);
158 @param mqc MQC handle
160 void mqc_reset_enc(opj_mqc_t *mqc);
162 RESTART mode switch (TERMALL)
163 @param mqc MQC handle
164 @return Returns 1 (always)
166 int mqc_restart_enc(opj_mqc_t *mqc);
168 RESTART mode switch (TERMALL) reinitialisation
169 @param mqc MQC handle
171 void mqc_restart_init_enc(opj_mqc_t *mqc);
173 ERTERM mode switch (PTERM)
174 @param mqc MQC handle
176 void mqc_erterm_enc(opj_mqc_t *mqc);
178 SEGMARK mode switch (SEGSYM)
179 @param mqc MQC handle
181 void mqc_segmark_enc(opj_mqc_t *mqc);
183 Initialize the decoder
184 @param mqc MQC handle
185 @param bp Pointer to the start of the buffer from which the bytes will be read
186 @param len Length of the input buffer
188 void mqc_init_dec(opj_mqc_t *mqc, unsigned char *bp, int len);
191 @param mqc MQC handle
192 @return Returns the decoded symbol (0 or 1)
194 int mqc_decode(opj_mqc_t *const mqc);
195 /* ----------------------------------------------------------------------- */