ref: 5323bf5d517d433e45291c1e78292e9cf3e1ac10
dir: /jpc_mqdec.c/
/*
* 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
*
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person (the
* "User") obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, and/or sell copies of the Software, and to permit
* persons to whom the Software is furnished to do so, subject to the
* following conditions:
*
* 1. The above copyright notices and this permission notice (which
* includes the disclaimer below) shall be included in all copies or
* substantial portions of the Software.
*
* 2. The name of a copyright holder shall not be used to endorse or
* promote products derived from the Software without specific prior
* written permission.
*
* THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS
* LICENSE. NO USE OF THE SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER
* THIS DISCLAIMER. THE SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
* "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
* INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. NO ASSURANCES ARE
* PROVIDED BY THE COPYRIGHT HOLDERS THAT THE SOFTWARE DOES NOT INFRINGE
* THE PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OF ANY OTHER ENTITY.
* EACH COPYRIGHT HOLDER DISCLAIMS ANY LIABILITY TO THE USER FOR CLAIMS
* BROUGHT BY ANY OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL
* PROPERTY RIGHTS OR OTHERWISE. AS A CONDITION TO EXERCISING THE RIGHTS
* GRANTED HEREUNDER, EACH USER HEREBY ASSUMES SOLE RESPONSIBILITY TO SECURE
* ANY OTHER INTELLECTUAL PROPERTY RIGHTS NEEDED, IF ANY. THE SOFTWARE
* IS NOT FAULT-TOLERANT AND IS NOT INTENDED FOR USE IN MISSION-CRITICAL
* SYSTEMS, SUCH AS THOSE USED IN THE OPERATION OF NUCLEAR FACILITIES,
* AIRCRAFT NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL
* SYSTEMS, DIRECT LIFE SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH
* THE FAILURE OF THE SOFTWARE OR SYSTEM COULD LEAD DIRECTLY TO DEATH,
* PERSONAL INJURY, OR SEVERE PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH
* RISK ACTIVITIES"). THE COPYRIGHT HOLDERS SPECIFICALLY DISCLAIM ANY
* EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR HIGH RISK ACTIVITIES.
*
* __END_OF_JASPER_LICENSE__
*/
/*
* MQ Arithmetic Decoder
*
* $Id$
*/
/******************************************************************************\
* Includes.
\******************************************************************************/
#include "jpc_mqdec.h"
#include "jasper/jas_types.h"
#include "jasper/jas_malloc.h"
#include "jasper/jas_math.h"
#include "jasper/jas_debug.h"
/******************************************************************************\
* Local macros.
\******************************************************************************/
#ifndef NDEBUG
#define MQDEC_CALL(n, x) \
((jas_getdbglevel() >= (n)) ? ((void)(x)) : ((void)0))
#else
#define MQDEC_CALL(n, x)
#endif
/******************************************************************************\
* Local function prototypes.
\******************************************************************************/
static void jpc_mqdec_bytein(jpc_mqdec_t *mqdec);
/******************************************************************************\
* Code for creation and destruction of a MQ decoder.
\******************************************************************************/
/* Create a MQ decoder. */
jpc_mqdec_t *jpc_mqdec_create(unsigned maxctxs, jas_stream_t *in)
{
jpc_mqdec_t *mqdec;
/* There must be at least one context. */
assert(maxctxs > 0);
/* Allocate memory for the MQ decoder. */
if (!(mqdec = jas_malloc(sizeof(jpc_mqdec_t)))) {
goto error;
}
mqdec->in = in;
mqdec->maxctxs = maxctxs;
/* Allocate memory for the per-context state information. */
if (!(mqdec->ctxs = jas_alloc2(mqdec->maxctxs, sizeof(jpc_mqstate_t *)))) {
goto error;
}
/* Set the current context to the first context. */
mqdec->curctx = mqdec->ctxs;
/* If an input stream has been associated with the MQ decoder,
initialize the decoder state from the stream. */
if (mqdec->in) {
jpc_mqdec_init(mqdec);
}
/* Initialize the per-context state information. */
jpc_mqdec_setctxs(mqdec, 0, 0);
return mqdec;
error:
/* Oops... Something has gone wrong. */
if (mqdec) {
jpc_mqdec_destroy(mqdec);
}
return 0;
}
/* Destroy a MQ decoder. */
void jpc_mqdec_destroy(jpc_mqdec_t *mqdec)
{
jas_free(mqdec->ctxs);
jas_free(mqdec);
}
/******************************************************************************\
* Code for initialization of a MQ decoder.
\******************************************************************************/
/* Initialize the state of a MQ decoder. */
void jpc_mqdec_init(jpc_mqdec_t *mqdec)
{
int c;
mqdec->eof = false;
mqdec->creg = 0;
/* Get the next byte from the input stream. */
if ((c = jas_stream_getc(mqdec->in)) == EOF) {
/* We have encountered an I/O error or EOF. */
c = 0xff;
mqdec->eof = true;
}
mqdec->inbuffer = c;
mqdec->creg += mqdec->inbuffer << 16;
jpc_mqdec_bytein(mqdec);
mqdec->creg <<= 7;
mqdec->ctreg -= 7;
mqdec->areg = 0x8000;
}
/* Set the input stream for a MQ decoder. */
void jpc_mqdec_setinput(jpc_mqdec_t *mqdec, jas_stream_t *in)
{
mqdec->in = in;
}
/* Initialize one or more contexts. */
void jpc_mqdec_setctxs(const jpc_mqdec_t *mqdec, unsigned numctxs, const jpc_mqctx_t *ctxs)
{
const jpc_mqstate_t **ctx;
ctx = mqdec->ctxs;
unsigned n = JAS_MIN(mqdec->maxctxs, numctxs);
while (n-- > 0) {
*ctx = &jpc_mqstates[2 * ctxs->ind + ctxs->mps];
++ctx;
++ctxs;
}
n = mqdec->maxctxs - numctxs;
while (n-- > 0) {
*ctx = &jpc_mqstates[0];
++ctx;
}
}
/******************************************************************************\
* Code for decoding a bit.
\******************************************************************************/
/* Decode a bit. */
bool jpc_mqdec_getbit_func(register jpc_mqdec_t *mqdec)
{
bool bit;
JAS_DBGLOG(100, ("jpc_mqdec_getbit_func(%p)\n", mqdec));
bit = jpc_mqdec_getbit_macro(mqdec);
JAS_DBGLOG(100, ("ctx = %d, decoded %d\n", mqdec->curctx -
mqdec->ctxs, bit));
return bit;
}
static void jpc_mqdec_renormd(jpc_mqdec_t *mqdec)
{
do {
if (!mqdec->ctreg)
jpc_mqdec_bytein(mqdec);
mqdec->areg <<= 1;
mqdec->creg <<= 1;
--mqdec->ctreg;
} while (!(mqdec->areg & 0x8000));
}
/* Apply MPS_EXCHANGE algorithm (with RENORMD). */
bool jpc_mqdec_mpsexchrenormd(register jpc_mqdec_t *mqdec)
{
register const jpc_mqstate_t *state = *mqdec->curctx;
bool ret = jpc_mqdec_mpsexchange(mqdec->areg, state->qeval, mqdec->curctx);
jpc_mqdec_renormd(mqdec);
return ret;
}
/* Apply LPS_EXCHANGE algorithm (with RENORMD). */
bool jpc_mqdec_lpsexchrenormd(register jpc_mqdec_t *mqdec)
{
register const jpc_mqstate_t *state = *mqdec->curctx;
bool ret = jpc_mqdec_lpsexchange(&mqdec->areg, state->qeval, mqdec->curctx);
jpc_mqdec_renormd(mqdec);
return ret;
}
/******************************************************************************\
* Support code.
\******************************************************************************/
/* Apply the BYTEIN algorithm. */
static void jpc_mqdec_bytein(jpc_mqdec_t *mqdec)
{
int c;
unsigned char prevbuf;
if (!mqdec->eof) {
if ((c = jas_stream_getc(mqdec->in)) == EOF) {
mqdec->eof = true;
c = 0xff;
}
prevbuf = mqdec->inbuffer;
mqdec->inbuffer = c;
if (prevbuf == 0xff) {
if (c > 0x8f) {
mqdec->creg += 0xff00;
mqdec->ctreg = 8;
} else {
mqdec->creg += c << 9;
mqdec->ctreg = 7;
}
} else {
mqdec->creg += c << 8;
mqdec->ctreg = 8;
}
} else {
mqdec->creg += 0xff00;
mqdec->ctreg = 8;
}
}