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FileReaderDCC.cc

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#include "FileReaderDCC.h"
#include <iostream>    // cerr
#include <errno.h>     // errno
#include <string.h>    // bzero, memcpy
#include <stdlib.h>    // exit
#include <sys/types.h> // open
#include <sys/stat.h>  // open
#include <fcntl.h>     // open
#include <unistd.h>    // read, close

FileReaderDCC::FileReaderDCC(void){
        if( sizeof(unsigned long long)!=8 || sizeof(unsigned short)!=2 )
                throw std::runtime_error(std::string("Wrong platform: sizeof(unsigned long long)!=8 || sizeof(unsigned short)!=2"));
        raw_event = new unsigned short [200000*40];
        end = (file_buffer_end = file_buffer + sizeof(file_buffer)/sizeof(unsigned long long));
        bzero(raw_event,  sizeof(raw_event)  );
        bzero(file_buffer,sizeof(file_buffer));
        word_0=0; word_1=0; word_2=0;
        eventStatus = 0;
        selectCriteria = Header|Trailer;
        rejectCriteria = DCCoversize|FFFF|Unknown;
        acceptCriteria = 0x3F; // Everything
        fd = 0;
}

FileReaderDCC::~FileReaderDCC(void){ if( fd ) close(fd); }

int FileReaderDCC::open(const char *filename) throw (std::runtime_error) {
        if( fd ) close(fd);
        fd = ::open(filename,O_RDONLY|O_LARGEFILE);
        if( fd == -1 ) throw ( std::runtime_error(std::string("Error opening ").append(filename).append(" data file.")) );
        return fd;
}

size_t FileReaderDCC::read(const unsigned short* &buf) throw (std::runtime_error) {
        // Check for ubnormal situation
        if( end>file_buffer_end || end<file_buffer ) throw ( std::runtime_error("Error of reading") );
        if( !fd ) throw ( std::runtime_error("Open some file first") );

        unsigned long long *start = end;
        unsigned short     *event = raw_event;

        eventStatus = 0;
        size_t dccWordCount = 0;
        end = 0;

        while( !end && dccWordCount<50000*40 ){
                unsigned long long *dccWord = start;
                unsigned long long preHeader = 0;

                // Did we reach end of current buffer and want to read next block?
                // If it was first time and we don't have file buffer then we won't get inside
                while( dccWord<file_buffer_end && dccWordCount<50000 ){
                        word_0 =  word_1; // delay by 2 DCC words
                        word_1 =  word_2; // delay by 1 DCC word
                        word_2 = *dccWord;// current DCC word
                        if( (word_1&0xF0000000000000FFLL)==0x500000000000005FLL && // let's call this a preHeader
                                (word_2&0xFF000000000000FFLL)==0xD900000000000017LL ){ // and this is a header
                                if( eventStatus&Header ){ // Second header
                                        word_2 = word_1; // Fall back to get rigth preHeader next time
                                        end = dccWord;   // Even if we end with preHeader of next evet put it to the end of this event too
                                        break;
                                }
                                if( dccWordCount>1 ){ // Extra words between trailer and header
                                        if( (word_0&0xFFFFFFFFFFFF0000LL)==0xFFFFFFFFFFFF0000LL ) eventStatus |= FFFF;
                                        word_2 = word_1; // Fall back to get rigth preHeader next time
                                        end = dccWord;
                                        break;
                                }
                                eventStatus |= Header;
                                if( event==raw_event ) preHeader = word_1; // If preHeader not yet in event then put it there
                                start = dccWord;
                        }
                        if( (word_1&0xFF00000000000000LL)==0xEF00000000000000LL &&
                                (word_2&0xFF0000000000000FLL)==0xAF00000000000007LL ){
                                eventStatus |= Trailer;
                                end = ++dccWord;
                                break;
                        }
                        // Increase counters by one DCC word
                        dccWord++;
                        dccWordCount++;
                }

                // If have DCC Header
                if( preHeader ){
                        // Need to account first word of DCC Header
                        memcpy(event,&preHeader,sizeof(preHeader));
                        event += sizeof(preHeader)/sizeof(unsigned short);
                }

                // Take care of the rest
                memcpy(event,start,(dccWord-start)*sizeof(unsigned long long));
                event += (dccWord-start)*sizeof(unsigned long long)/sizeof(unsigned short);

                // If reach max length
                if( dccWordCount==50000*40 ){ end = dccWord; break; }

                if( !end ){
                        // Need to read next block for the rest of this event
                        ssize_t length = ::read(fd,file_buffer,sizeof(file_buffer));
                        if( length==-1 ) throw ( std::runtime_error("Error of reading") );
                        if( length== 0 ){
                                eventStatus |= EndOfStream;
                                end = (file_buffer_end = file_buffer + sizeof(file_buffer)/sizeof(unsigned long long));
                                break;
                        }
                        file_buffer_end = file_buffer + length/sizeof(unsigned long long);

                        // Will start from the beginning of new buffer next time we read it
                        start = file_buffer;
                }
        }

        if( !end ) eventStatus |= DCCoversize;
        if( !(eventStatus&Header) && !(eventStatus&Trailer) && !(eventStatus&FFFF) ) eventStatus |= Unknown;

        buf = (const unsigned short*)raw_event;
        return (eventStatus&FFFF?event-raw_event-4:event-raw_event);
}

size_t FileReaderDCC::next(const unsigned short* &buf) throw(std::runtime_error) {
        size_t size=0;
        do {
                if( (size = read(buf)) == 0 ) break;
        } while( rejectCriteria&eventStatus || !(acceptCriteria&eventStatus) || (selectCriteria?selectCriteria!=eventStatus:0) );
        return size;
}

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