jpc_mqdec.h

/*
 * Copyright (c) 1999-2000 Image Power, Inc. and the University of
 *   British Columbia.
 * Copyright (c) 2001-2003 Michael David Adams.
 * All rights reserved.
 */
 
/* __START_OF_JASPER_LICENSE__
 * 
 * JasPer License Version 2.0
 * 
 * Copyright (c) 2001-2006 Michael David Adams
 * Copyright (c) 1999-2000 Image Power, Inc.
 * Copyright (c) 1999-2000 The University of British Columbia
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 */
 
/*
 * MQ Arithmetic Decoder
 *
 * $Id$
 */
 
#ifndef JPC_MQDEC_H
#define JPC_MQDEC_H
 
/******************************************************************************\
* Includes.
\******************************************************************************/
 
#include "jasper/jas_types.h"
#include "jasper/jas_stream.h"
 
#include "jpc_mqcod.h"
 
#include <stdio.h>
 
/******************************************************************************\
* Types.
\******************************************************************************/
 
/* MQ arithmetic decoder. */
 
typedef struct {
 
        /* The C register. */
        uint_least32_t creg;
 
        /* The A register. */
        uint_least32_t areg;
 
        /* The CT register. */
        uint_least32_t ctreg;
 
        /* The current context. */
        const jpc_mqstate_t **curctx;
 
        /* The per-context information. */
        const jpc_mqstate_t **ctxs;
 
        /* The maximum number of contexts. */
        unsigned maxctxs;
 
        /* The stream from which to read data. */
        jas_stream_t *in;
 
        /* The last character read. */
        jas_uchar inbuffer;
 
        /* The EOF indicator. */
        bool eof;
 
} jpc_mqdec_t;
 
/******************************************************************************\
* Functions/macros for construction and destruction.
\******************************************************************************/
 
/* Create a MQ decoder. */
jpc_mqdec_t *jpc_mqdec_create(unsigned maxctxs, jas_stream_t *in);
 
/* Destroy a MQ decoder. */
void jpc_mqdec_destroy(jpc_mqdec_t *dec);
 
/******************************************************************************\
* Functions/macros for initialization.
\******************************************************************************/
 
/* Set the input stream associated with a MQ decoder. */
void jpc_mqdec_setinput(jpc_mqdec_t *dec, jas_stream_t *in);
 
/* Initialize a MQ decoder. */
void jpc_mqdec_init(jpc_mqdec_t *dec);
 
/******************************************************************************\
* Functions/macros for manipulating contexts.
\******************************************************************************/
 
/* Set the current context for a MQ decoder. */
static inline void jpc_mqdec_setcurctx(jpc_mqdec_t *dec, unsigned ctxno)
{
        dec->curctx = &dec->ctxs[ctxno];
}
 
/* Set the state information for all contexts of a MQ decoder. */
void jpc_mqdec_setctxs(const jpc_mqdec_t *dec, unsigned numctxs, const jpc_mqctx_t *ctxs);
 
/******************************************************************************\
* Functions/macros for decoding bits.
\******************************************************************************/
 
/* Decode a symbol. */
#ifdef NDEBUG
#define jpc_mqdec_getbit(dec) \
        jpc_mqdec_getbit_macro(dec)
#else
#define jpc_mqdec_getbit(dec) \
        jpc_mqdec_getbit_func(dec)
#endif
 
/* Decode a symbol (assuming an unskewed probability distribution). */
#ifdef NDEBUG
#define jpc_mqdec_getbitnoskew(dec) \
        jpc_mqdec_getbit_macro(dec)
#else
#define jpc_mqdec_getbitnoskew(dec) \
        jpc_mqdec_getbit_func(dec)
#endif
 
/******************************************************************************\
* Functions/macros for debugging.
\******************************************************************************/
 
/* Dump the MQ decoder state for debugging. */
void jpc_mqdec_dump(const jpc_mqdec_t *dec);
 
/******************************************************************************\
* EVERYTHING BELOW THIS POINT IS IMPLEMENTATION SPECIFIC AND NOT PART OF THE
* APPLICATION INTERFACE.  DO NOT RELY ON ANY OF THE INTERNAL FUNCTIONS/MACROS
* GIVEN BELOW.
\******************************************************************************/
 
bool jpc_mqdec_mpsexchrenormd(jpc_mqdec_t *dec);
bool jpc_mqdec_lpsexchrenormd(jpc_mqdec_t *dec);
 
JAS_FORCE_INLINE
static bool jpc_mqdec_getbit_macro(jpc_mqdec_t *dec)
{
        const jpc_mqstate_t *const state = *dec->curctx;
 
        dec->areg -= state->qeval;
 
        if (dec->creg >= (uint_least32_t)state->qeval << 16) {
                dec->creg -= (uint_least32_t)state->qeval << 16;
                return dec->areg & 0x8000
                        ? state->mps
                        : jpc_mqdec_mpsexchrenormd(dec);
        } else {
                return jpc_mqdec_lpsexchrenormd(dec);
        }
}
 
JAS_FORCE_INLINE
static bool jpc_mqdec_mpsexchange(uint_least32_t areg, uint_least32_t delta, const jpc_mqstate_t **curctx)
{
        if (areg < delta) {
                const jpc_mqstate_t *state = *curctx;
                /* LPS decoded. */
                *curctx = state->nlps;
                return !state->mps;
        } else {
                const jpc_mqstate_t *state = *curctx;
                /* MPS decoded. */
                *curctx = state->nmps;
                return state->mps;
        }
}
 
JAS_FORCE_INLINE
static bool jpc_mqdec_lpsexchange(uint_least32_t *areg_p, uint_least32_t delta, const jpc_mqstate_t **curctx)
{
        if (*areg_p >= delta) {
                const jpc_mqstate_t *state = *curctx;
                *areg_p = delta;
                *curctx = state->nlps;
                return !state->mps;
        } else {
                const jpc_mqstate_t *state = *curctx;
                *areg_p = delta;
                *curctx = state->nmps;
                return state->mps;
        }
}
 
bool jpc_mqdec_getbit_func(jpc_mqdec_t *dec);
 
#endif