ref: 0d62e74e14ccf4e123d5c2d7af76cb02e695c0ee
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)); 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; } 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; } } /******************************************************************************\ * Code for debugging. \******************************************************************************/ /* Dump a MQ decoder to a stream for debugging. */ void jpc_mqdec_dump(const 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 = %" PRIdPTR ", ", mqdec->curctx - mqdec->ctxs); fprintf(out, "IND %" PRIdPTR ", MPS %d, QEVAL %"PRIxLEAST16"\n", *mqdec->curctx - jpc_mqstates, (*mqdec->curctx)->mps, (*mqdec->curctx)->qeval); }