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42 @brief Implementation of an MQ-Coder (MQC)
44 The functions in MQC.C have for goal to realize the MQ-coder operations. The functions
45 in MQC.C are used by some function in T1.C.
48 /** @defgroup MQC MQC - Implementation of an MQ-Coder */
52 This struct defines the state of a context.
54 typedef struct opj_mqc_state {
55 /** the probability of the Least Probable Symbol (0.75->0x8000, 1.5->0xffff) */
57 /** the Most Probable Symbol (0 or 1) */
59 /** next state if the next encoded symbol is the MPS */
60 struct opj_mqc_state *nmps;
61 /** next state if the next encoded symbol is the LPS */
62 struct opj_mqc_state *nlps;
65 #define MQC_NUMCTXS 19
70 typedef struct opj_mqc {
77 opj_mqc_state_t *ctxs[MQC_NUMCTXS];
78 opj_mqc_state_t **curctx;
80 unsigned char *buffer;
84 /** @name Exported functions */
86 /* ----------------------------------------------------------------------- */
88 Create a new MQC handle
89 @return Returns a new MQC handle if successful, returns NULL otherwise
91 opj_mqc_t* mqc_create(void);
93 Destroy a previously created MQC handle
94 @param mqc MQC handle to destroy
96 void mqc_destroy(opj_mqc_t *mqc);
98 Return the number of bytes written/read since initialisation
100 @return Returns the number of bytes already encoded
102 int mqc_numbytes(opj_mqc_t *mqc);
104 Reset the states of all the context of the coder/decoder
105 (each context is set to a state where 0 and 1 are more or less equiprobable)
106 @param mqc MQC handle
108 void mqc_resetstates(opj_mqc_t *mqc);
110 Set the state of a particular context
111 @param mqc MQC handle
112 @param ctxno Number that identifies the context
113 @param msb The MSB of the new state of the context
114 @param prob Number that identifies the probability of the symbols for the new state of the context
116 void mqc_setstate(opj_mqc_t *mqc, int ctxno, int msb, int prob);
118 Initialize the encoder
119 @param mqc MQC handle
120 @param bp Pointer to the start of the buffer where the bytes will be written
122 void mqc_init_enc(opj_mqc_t *mqc, unsigned char *bp);
124 Set the current context used for coding/decoding
125 @param mqc MQC handle
126 @param ctxno Number that identifies the context
128 #define mqc_setcurctx(mqc, ctxno) (mqc)->curctx = &(mqc)->ctxs[(int)(ctxno)]
130 Encode a symbol using the MQ-coder
131 @param mqc MQC handle
132 @param d The symbol to be encoded (0 or 1)
134 void mqc_encode(opj_mqc_t *mqc, int d);
136 Flush the encoder, so that all remaining data is written
137 @param mqc MQC handle
139 void mqc_flush(opj_mqc_t *mqc);
141 BYPASS mode switch, initialization operation.
143 <h2>Not fully implemented and tested !!</h2>
144 @param mqc MQC handle
146 void mqc_bypass_init_enc(opj_mqc_t *mqc);
148 BYPASS mode switch, coding operation.
150 <h2>Not fully implemented and tested !!</h2>
151 @param mqc MQC handle
152 @param d The symbol to be encoded (0 or 1)
154 void mqc_bypass_enc(opj_mqc_t *mqc, int d);
156 BYPASS mode switch, flush operation
157 <h2>Not fully implemented and tested !!</h2>
158 @param mqc MQC handle
159 @return Returns 1 (always)
161 int mqc_bypass_flush_enc(opj_mqc_t *mqc);
164 @param mqc MQC handle
166 void mqc_reset_enc(opj_mqc_t *mqc);
168 RESTART mode switch (TERMALL)
169 @param mqc MQC handle
170 @return Returns 1 (always)
172 int mqc_restart_enc(opj_mqc_t *mqc);
174 RESTART mode switch (TERMALL) reinitialisation
175 @param mqc MQC handle
177 void mqc_restart_init_enc(opj_mqc_t *mqc);
179 ERTERM mode switch (PTERM)
180 @param mqc MQC handle
182 void mqc_erterm_enc(opj_mqc_t *mqc);
184 SEGMARK mode switch (SEGSYM)
185 @param mqc MQC handle
187 void mqc_segmark_enc(opj_mqc_t *mqc);
189 Initialize the decoder
190 @param mqc MQC handle
191 @param bp Pointer to the start of the buffer from which the bytes will be read
192 @param len Length of the input buffer
194 void mqc_init_dec(opj_mqc_t *mqc, unsigned char *bp, int len);
197 @param mqc MQC handle
198 @return Returns the decoded symbol (0 or 1)
200 int mqc_decode(opj_mqc_t *const mqc);
201 /* ----------------------------------------------------------------------- */