141 lines
3.6 KiB
C
141 lines
3.6 KiB
C
/*
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* Copyright (c) 2004, Yannick Verschueren
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* Copyright (c) 2004, Communications and remote sensing Laboratory, Universite catholique de Louvain, Belgium
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "cio.h"
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/*
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* Read the information contains in VBAS [JPP/JPT stream message header]
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* Store information (7 bits) in value
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*
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*/
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unsigned int jpt_read_VBAS_info(unsigned int value)
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{
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char elmt;
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elmt = cio_read(1);
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while ((elmt >> 7) == 1)
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{
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value = value << 7;
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value |= (elmt & 0x7f);
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elmt = cio_read(1);
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}
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value = value << 7;
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value |= (elmt & 0x7f);
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return value;
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}
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/*
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* Read the message header for a JPP/JPT - stream
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*
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*/
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void jpt_read_Msg_Header()
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{
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char elmt, Class, CSn, last_byte, Aux;
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unsigned int ID=0, Class_ID=0, CSn_ID=0, Msg_offset=0, Msg_length=0, Layer_nb;
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/* ------------- */
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/* VBAS : Bin-ID */
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/* ------------- */
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elmt = cio_read(1);
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/* See for Class and CSn */
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switch((elmt>>5) & 0x03)
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{
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case 0:
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fprintf(stderr,"Forbidden value encounter in message header !!\n");
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break;
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case 1:
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Class = 0;
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CSn = 0;
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break;
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case 2:
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Class = 1;
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CSn = 0;
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break;
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case 3:
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Class = 1;
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CSn = 1;
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break;
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default :
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break;
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}
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/* see information on bits 'c' [p 10 : A.2.1 general, ISO/IEC FCD 15444-9] */
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if (((elmt>>3) & 0x01) == 1)
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last = 1;
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/* In-class identifier */
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ID |= (elmt & 0x0f);
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if ((elmt>>7)==1)
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ID = jpt_read_VBAS_info(ID);
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/* ------------ */
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/* VBAS : Class */
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/* ------------ */
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if (Class==1)
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{
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Class_ID = jpt_read_VBAS_info(Class_ID);
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} else
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{
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/* 0 si pas de precedent message */
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/* inchange sinon */
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}
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/* ---------- */
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/* VBAS : CSn */
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/* ---------- */
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if (CSn==1)
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{
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CSn_ID = jpt_read_VBAS_info(CSn_ID);
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} else
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{
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/* 0 si pas de precedent message */
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/* inchange sinon */
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}
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/* ----------------- */
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/* VBAS : Msg_offset */
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/* ----------------- */
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Msg_offset = jpt_read_VBAS_info(Msg_offset);
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/* ----------------- */
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/* VBAS : Msg_length */
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/* ----------------- */
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Msg_length = jpt_read_VBAS_info(Msg_length);
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/* ---------- */
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/* VBAS : Aux */
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/* ---------- */
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if (CSn_ID == 1)
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Layer_nb = jpt_read_VBAS_info(Layer_nb);
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}
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