text: /*
   * 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 <assert.h>
  #include <stdlib.h>
  #include <stdarg.h>
  
  #include "jasper/jas_types.h"
  #include "jasper/jas_malloc.h"
  #include "jasper/jas_math.h"
  #include "jasper/jas_debug.h"
  
  #include "jpc_mqdec.h"
  
  /******************************************************************************\
  * Local macros.
  \******************************************************************************/
  
  #if defined(DEBUG)
  #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(int 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)
  {
  	if (mqdec->ctxs) {
  		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 = 0;
  	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 = 1;
  	}
  	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(jpc_mqdec_t *mqdec, int numctxs, jpc_mqctx_t *ctxs)
  {
  	jpc_mqstate_t **ctx;
  	int n;
  
  	ctx = mqdec->ctxs;
  	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;
  	}
  }
  
  /* Initialize a context. */
  
  void jpc_mqdec_setctx(jpc_mqdec_t *mqdec, int ctxno, jpc_mqctx_t *ctx)
  {
  	jpc_mqstate_t **ctxi;
  	ctxi = &mqdec->ctxs[ctxno];
  	*ctxi = &jpc_mqstates[2 * ctx->ind + ctx->mps];
  }
  
  /******************************************************************************\
  * Code for decoding a bit.
  \******************************************************************************/
  
  /* Decode a bit. */
  
  int jpc_mqdec_getbit_func(register jpc_mqdec_t *mqdec)
  {
  	int bit;
  	JAS_DBGLOG(100, ("jpc_mqdec_getbit_func(%p)\n", mqdec));
  	MQDEC_CALL(100, jpc_mqdec_dump(mqdec, stderr));
  	bit = jpc_mqdec_getbit_macro(mqdec);
  	MQDEC_CALL(100, jpc_mqdec_dump(mqdec, stderr));
  	JAS_DBGLOG(100, ("ctx = %d, decoded %d\n", mqdec->curctx -
  	  mqdec->ctxs, bit));
  	return bit;
  }
  
  /* Apply MPS_EXCHANGE algorithm (with RENORMD). */
  int jpc_mqdec_mpsexchrenormd(register jpc_mqdec_t *mqdec)
  {
  	int ret;
  	register jpc_mqstate_t *state = *mqdec->curctx;
  	jpc_mqdec_mpsexchange(mqdec->areg, state->qeval, mqdec->curctx, ret);
  	jpc_mqdec_renormd(mqdec->areg, mqdec->creg, mqdec->ctreg, mqdec->in,
  	  mqdec->eof, mqdec->inbuffer);
  	return ret;
  }
  
  /* Apply LPS_EXCHANGE algorithm (with RENORMD). */
  int jpc_mqdec_lpsexchrenormd(register jpc_mqdec_t *mqdec)
  {
  	int ret;
  	register jpc_mqstate_t *state = *mqdec->curctx;
  	jpc_mqdec_lpsexchange(mqdec->areg, state->qeval, mqdec->curctx, ret);
  	jpc_mqdec_renormd(mqdec->areg, mqdec->creg, mqdec->ctreg, mqdec->in,
  	  mqdec->eof, mqdec->inbuffer);
  	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 = 1;
  			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;
  	}
  }
  
  /******************************************************************************\
  * Code for debugging.
  \******************************************************************************/
  
  /* Dump a MQ decoder to a stream for debugging. */
  
  void jpc_mqdec_dump(jpc_mqdec_t *mqdec, FILE *out)
  {
  	fprintf(out, "MQDEC A = %08lx, C = %08lx, CT=%08lx, ",
  	  (unsigned long) mqdec->areg, (unsigned long) mqdec->creg,
  	  (unsigned long) mqdec->ctreg);
  	fprintf(out, "CTX = %d, ", mqdec->curctx - mqdec->ctxs);
  	fprintf(out, "IND %d, MPS %d, QEVAL %x\n", *mqdec->curctx -
  	  jpc_mqstates, (*mqdec->curctx)->mps, (*mqdec->curctx)->qeval);
  }
  