/[Biblio-Isis]/trunk/lib/Biblio/Isis.pm
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trunk/IsisDB.pm revision 12 by dpavlin, Wed Dec 29 20:10:11 2004 UTC trunk/lib/Biblio/Isis.pm revision 39 by dpavlin, Thu Jan 27 22:01:17 2005 UTC
# Line 1  Line 1 
1  package IsisDB;  package Biblio::Isis;
2  use strict;  use strict;
3    
4  use Carp;  use Carp;
5    use File::Glob qw(:globally :nocase);
6    
7  use Data::Dumper;  use Data::Dumper;
8    
9  BEGIN {  BEGIN {
10          use Exporter ();          use Exporter ();
11          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
12          $VERSION     = 0.04;          $VERSION     = 0.12;
13          @ISA         = qw (Exporter);          @ISA         = qw (Exporter);
14          #Give a hoot don't pollute, do not export more than needed by default          #Give a hoot don't pollute, do not export more than needed by default
15          @EXPORT      = qw ();          @EXPORT      = qw ();
# Line 18  BEGIN { Line 20  BEGIN {
20    
21  =head1 NAME  =head1 NAME
22    
23  IsisDB - Read CDS/ISIS database  Biblio::Isis - Read CDS/ISIS, WinISIS and IsisMarc database
24    
25  =head1 SYNOPSIS  =head1 SYNOPSIS
26    
27    use IsisDB;    use Biblio::Isis;
28    
29    my $isis = new IsisDB(    my $isis = new Biblio::Isis(
30          isisdb => './cds/cds',          isisdb => './cds/cds',
31    );    );
32    
33    for(my $mfn = 1; $mfn <= $isis->{'maxmfn'}; $mfn++) {    for(my $mfn = 1; $mfn <= $isis->count; $mfn++) {
34          print $isis->to_ascii($mfn),"\n";          print $isis->to_ascii($mfn),"\n";
35    }    }
36    
37  =head1 DESCRIPTION  =head1 DESCRIPTION
38    
39  This module will read CDS/ISIS databases and create hash values out of it.  This module will read ISIS databases created by DOS CDS/ISIS, WinIsis or
40  It can be used as perl-only alternative to OpenIsis module.  IsisMarc. It can be used as perl-only alternative to OpenIsis module which
41    seems to depriciate it's old C<XS> bindings for perl.
42  This will module will always be slower that OpenIsis module which use C  
43  library. However, since it's written in perl, it's platform independent (so  It can create hash values from data in ISIS database (using C<to_hash>),
44  you don't need C compiler), and can be easily modified.  ASCII dump (using C<to_ascii>) or just hash with field names and packed
45    values (like C<^asomething^belse>).
46    
47  Unique feature of this module is ability to C<include_deleted> records.  Unique feature of this module is ability to C<include_deleted> records.
48  It will also skip zero sized fields (OpenIsis has a bug in XS bindings, so  It will also skip zero sized fields (OpenIsis has a bug in XS bindings, so
49  fields which are zero sized will be filled with random junk from memory).  fields which are zero sized will be filled with random junk from memory).
50    
51    It also has support for identifiers (only if ISIS database is created by
52    IsisMarc), see C<to_hash>.
53    
54    This module will always be slower than OpenIsis module which use C
55    library. However, since it's written in perl, it's platform independent (so
56    you don't need C compiler), and can be easily modified. I hope that it
57    creates data structures which are easier to use than ones created by
58    OpenIsis, so reduced time in other parts of the code should compensate for
59    slower performance of this module (speed of reading ISIS database is
60    rarely an issue).
61    
62  =head1 METHODS  =head1 METHODS
63    
64  =cut  =cut
# Line 65  fields which are zero sized will be fill Line 79  fields which are zero sized will be fill
79    
80  =head2 new  =head2 new
81    
82  Open CDS/ISIS database  Open ISIS database
83    
84   my $isis = new IsisDB(   my $isis = new Biblio::Isis(
85          isisdb => './cds/cds',          isisdb => './cds/cds',
86          read_fdt => 1,          read_fdt => 1,
87          include_deleted => 1,          include_deleted => 1,
# Line 84  Options are described below: Line 98  Options are described below:
98    
99  =item isisdb  =item isisdb
100    
101  Prefix path to CDS/ISIS. It should contain full or relative path to database  This is full or relative path to ISIS database files which include
102  and common prefix of C<.FDT>, C<.MST>, C<.CNT>, C<.XRF> and C<.MST> files.  common prefix of C<.MST>, and C<.XRF> and optionally C<.FDT> (if using
103    C<read_fdt> option) files.
104    
105    In this example it uses C<./cds/cds.MST> and related files.
106    
107  =item read_fdt  =item read_fdt
108    
# Line 106  Dump a B<lot> of debugging output. Line 123  Dump a B<lot> of debugging output.
123    
124  =back  =back
125    
 It will also set C<$isis-E<gt>{'maxmfn'}> which is maximum MFN stored in database.  
   
126  =cut  =cut
127    
128  sub new {  sub new {
# Line 121  sub new { Line 136  sub new {
136                  $self->{$v} = {@_}->{$v};                  $self->{$v} = {@_}->{$v};
137          }          }
138    
139            my @isis_files = grep(/\.(FDT|MST|XRF|CNT)$/i,glob($self->{isisdb}."*"));
140    
141            foreach my $f (@isis_files) {
142                    my $ext = $1 if ($f =~ m/\.(\w\w\w)$/);
143                    $self->{lc($ext)."_file"} = $f;
144            }
145    
146            my @must_exist = qw(mst xrf);
147            push @must_exist, "fdt" if ($self->{read_fdt});
148    
149            foreach my $ext (@must_exist) {
150                    unless ($self->{$ext."_file"}) {
151                            carp "missing ",uc($ext)," file in ",$self->{isisdb};
152                            return;
153                    }
154            }
155    
156            print STDERR "## using files: ",join(" ",@isis_files),"\n" if ($self->{debug});
157    
158          # if you want to read .FDT file use read_fdt argument when creating class!          # if you want to read .FDT file use read_fdt argument when creating class!
159          if ({@_}->{read_fdt} && -e $self->{isisdb}.".FDT") {          if ($self->{read_fdt} && -e $self->{fdt_file}) {
160    
161                  # read the $db.FDT file for tags                  # read the $db.FDT file for tags
162                  my $fieldzone=0;                  my $fieldzone=0;
163    
164                  open(fileFDT, $self->{isisdb}.".FDT") || croak "can't read '$self->{isisdb}.FDT': $!";                  open(my $fileFDT, $self->{fdt_file}) || croak "can't read '$self->{fdt_file}': $!";
165                    binmode($fileFDT);
166    
167                  while (<fileFDT>) {                  while (<$fileFDT>) {
168                          chomp;                          chomp;
169                          if ($fieldzone) {                          if ($fieldzone) {
170                                  my $name=substr($_,0,30);                                  my $name=substr($_,0,30);
# Line 146  sub new { Line 181  sub new {
181                          }                          }
182                  }                  }
183                                    
184                  close(fileFDT);                  close($fileFDT);
185          }          }
186    
187          # Get the Maximum MFN from $db.MST          # Get the Maximum MFN from $db.MST
188    
189          open(fileMST,$self->{isisdb}.".MST") || croak "can't read '$self->{isisdb}.MST': $!";          open($self->{'fileMST'}, $self->{mst_file}) || croak "can't open '$self->{mst_file}': $!";
190            binmode($self->{'fileMST'});
191    
192          # MST format:   (* = 32 bit signed)          # MST format:   (* = 32 bit signed)
193          # CTLMFN*       always 0          # CTLMFN*       always 0
# Line 159  sub new { Line 195  sub new {
195          # NXTMFB*       last block allocated to master file          # NXTMFB*       last block allocated to master file
196          # NXTMFP        offset to next available position in last block          # NXTMFP        offset to next available position in last block
197          # MFTYPE        always 0 for user db file (1 for system)          # MFTYPE        always 0 for user db file (1 for system)
198          seek(fileMST,4,0);          seek($self->{'fileMST'},4,0) || croak "can't seek to offset 0 in MST: $!";
199    
200          my $buff;          my $buff;
201    
202          read(fileMST, $buff, 4);          read($self->{'fileMST'}, $buff, 4) || croak "can't read NXTMFN from MST: $!";
203          $self->{'NXTMFN'}=unpack("l",$buff) || carp "NXTNFN is zero";          $self->{'NXTMFN'}=unpack("V",$buff) || croak "NXTNFN is zero";
   
         # save maximum MFN  
         $self->{'maxmfn'} = $self->{'NXTMFN'} - 1;  
   
         close(fileMST);  
   
         # Get the index information from $db.CNT  
     
         open(fileCNT, $self->{isisdb}.".CNT") || croak "can't read '$self->{isisdb}.CNT': $!";  
   
         # There is two 26 Bytes fixed lenght records  
204    
205          #  0: IDTYPE    BTree type                              16          print STDERR Dumper($self),"\n" if ($self->{debug});
         #  2: ORDN      Nodes Order                             16  
         #  4: ORDF      Leafs Order                             16  
         #  6: N         Number of Memory buffers for nodes      16  
         #  8: K         Number of buffers for first level index 16  
         # 10: LIV       Current number of Index Levels          16  
         # 12: POSRX*    Pointer to Root Record in N0x           32  
         # 16: NMAXPOS*  Next Available position in N0x          32  
         # 20: FMAXPOS*  Next available position in L0x          32  
         # 24: ABNORMAL  Formal BTree normality indicator        16  
         # length: 26 bytes  
   
         sub unpack_cnt {  
                 my $self = shift;  
   
                 my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);  
   
                 my $buff = shift || return;  
                 my @arr = unpack("ssssssllls", $buff);  
   
                 print "unpack_cnt: ",join(" ",@arr),"\n" if ($self->{'debug'});  
   
                 my $IDTYPE = shift @arr;  
                 foreach (@flds) {  
                         $self->{$IDTYPE}->{$_} = abs(shift @arr);  
                 }  
         }  
206    
207          read(fileCNT, $buff, 26);          # open files for later
208          $self->unpack_cnt($buff);          open($self->{'fileXRF'}, $self->{xrf_file}) || croak "can't open '$self->{xrf_file}': $!";
209            binmode($self->{'fileXRF'});
         read(fileCNT, $buff, 26);  
         $self->unpack_cnt($buff);  
210    
211            $self ? return $self : return undef;
212    }
213    
214          close(fileCNT);  =head2 count
215    
216          print Dumper($self) if ($self->{debug});  Return number of records in database
217    
218          # open files for later    print $isis->count;
         open($self->{'fileXRF'}, $self->{isisdb}.".XRF") || croak "can't open '$self->{isisdb}.XRF': $!";  
219    
220          open($self->{'fileMST'}, $self->{isisdb}.".MST") || croak "can't open '$self->{isisdb}.MST': $!";  =cut
221    
222          $self ? return $self : return undef;  sub count {
223            my $self = shift;
224            return $self->{'NXTMFN'} - 1;
225  }  }
226    
227  =head2 fetch  =head2 fetch
# Line 231  Read record with selected MFN Line 231  Read record with selected MFN
231    my $rec = $isis->fetch(55);    my $rec = $isis->fetch(55);
232    
233  Returns hash with keys which are field names and values are unpacked values  Returns hash with keys which are field names and values are unpacked values
234  for that field (like C<^asometing^bsomething else>)  for that field like this:
235    
236      $rec = {
237        '210' => [ '^aNew York^cNew York University press^dcop. 1988' ],
238        '990' => [ '2140', '88', 'HAY' ],
239      };
240    
241  =cut  =cut
242    
# Line 240  sub fetch { Line 245  sub fetch {
245    
246          my $mfn = shift || croak "fetch needs MFN as argument!";          my $mfn = shift || croak "fetch needs MFN as argument!";
247    
248          print "fetch: $mfn\n" if ($self->{debug});          # is mfn allready in memory?
249            my $old_mfn = $self->{'current_mfn'} || -1;
250            return $self->{record} if ($mfn == $old_mfn);
251    
252            print STDERR "## fetch: $mfn\n" if ($self->{debug});
253    
254          # XXX check this?          # XXX check this?
255          my $mfnpos=($mfn+int(($mfn-1)/127))*4;          my $mfnpos=($mfn+int(($mfn-1)/127))*4;
256    
257          print "seeking to $mfnpos in file '$self->{isisdb}.XRF'\n" if ($self->{debug});          print STDERR "## seeking to $mfnpos in file '$self->{xrf_file}'\n" if ($self->{debug});
258          seek($self->{'fileXRF'},$mfnpos,0);          seek($self->{'fileXRF'},$mfnpos,0);
259    
260          my $buff;          my $buff;
261    
262            # delete old record
263            delete $self->{record};
264    
265          # read XRFMFB abd XRFMFP          # read XRFMFB abd XRFMFP
266          read($self->{'fileXRF'}, $buff, 4);          read($self->{'fileXRF'}, $buff, 4);
267          my $pointer=unpack("l",$buff) || carp "pointer is null";          my $pointer=unpack("V",$buff) || croak "pointer is null";
268    
269            # check for logically deleted record
270            if ($pointer & 0x80000000) {
271                    print STDERR "## record $mfn is logically deleted\n" if ($self->{debug});
272                    $self->{deleted} = $mfn;
273    
274                    return unless $self->{include_deleted};
275    
276                    # abs
277                    $pointer = ($pointer ^ 0xffffffff) + 1;
278            }
279    
280          my $XRFMFB = int($pointer/2048);          my $XRFMFB = int($pointer/2048);
281          my $XRFMFP = $pointer - ($XRFMFB*2048);          my $XRFMFP = $pointer - ($XRFMFB*2048);
282    
283          print "XRFMFB: $XRFMFB XRFMFP: $XRFMFP\n" if ($self->{debug});          # (XRFMFB - 1) * 512 + XRFMFP
284            # why do i have to do XRFMFP % 1024 ?
285    
286          # XXX fix this to be more readable!!          my $blk_off = (($XRFMFB - 1) * 512) + ($XRFMFP % 512);
         # e.g. (XRFMFB - 1) * 512 + XRFMFP  
   
         my $offset = $pointer;  
         my $offset2=int($offset/2048)-1;  
         my $offset22=int($offset/4096);  
         my $offset3=$offset-($offset22*4096);  
         if ($offset3>512) {  
                 $offset3=$offset3-2048;  
         }  
         my $offset4=($offset2*512)+$offset3;  
287    
288          print "$offset - $offset2 - $offset3 - $offset4\n" if ($self->{debug});          print STDERR "## pointer: $pointer XRFMFB: $XRFMFB XRFMFP: $XRFMFP offset: $blk_off\n" if ($self->{'debug'});
289    
290          # Get Record Information          # Get Record Information
291    
292          seek($self->{'fileMST'},$offset4,0);          seek($self->{'fileMST'},$blk_off,0) || croak "can't seek to $blk_off: $!";
293    
294          read($self->{'fileMST'}, $buff, 4);          read($self->{'fileMST'}, $buff, 4) || croak "can't read 4 bytes at offset $blk_off from MST file: $!";
295          my $value=unpack("l",$buff);          my $value=unpack("V",$buff);
296    
297            print STDERR "## offset for rowid $value is $blk_off (blk $XRFMFB off $XRFMFP)\n" if ($self->{debug});
298    
299          if ($value!=$mfn) {          if ($value!=$mfn) {
300  print ("Error: The MFN:".$mfn." is not found in MST(".$value.")");                      if ($value == 0) {
301                  return -1;      # XXX deleted record?                          print STDERR "## record $mfn is physically deleted\n" if ($self->{debug});
302          }                          $self->{deleted} = $mfn;
303                            return;
304                    }
305    
306  #       $MFRL=$self->Read16($fileMST);                  carp "Error: MFN ".$mfn." not found in MST file, found $value";    
307  #       $MFBWB=$self->Read32($fileMST);                  return;
308  #       $MFBWP=$self->Read16($fileMST);          }
 #       $BASE=$self->Read16($fileMST);  
 #       $NVF=$self->Read16($fileMST);  
 #       $STATUS=$self->Read16($fileMST);  
309    
310          read($self->{'fileMST'}, $buff, 14);          read($self->{'fileMST'}, $buff, 14);
311    
312          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("slssss", $buff);          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("vVvvvv", $buff);
313    
314          print "MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});          print STDERR "## MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});
315    
316          # delete old record          warn "MFRL $MFRL is not even number" unless ($MFRL % 2 == 0);
         delete $self->{record};  
317    
318          if (! $self->{'include_deleted'} && $MFRL < 0) {          warn "BASE is not 18+6*NVF" unless ($BASE == 18 + 6 * $NVF);
                 print "## logically deleted record $mfn, skipping...\n" if ($self->{debug});  
                 return;  
         }  
319    
320          # Get Directory Format          # Get Directory Format
321    
# Line 314  print ("Error: The MFN:".$mfn." is not f Line 325  print ("Error: The MFN:".$mfn." is not f
325    
326          read($self->{'fileMST'}, $buff, 6 * $NVF);          read($self->{'fileMST'}, $buff, 6 * $NVF);
327    
328          my $fld_len = 0;          my $rec_len = 0;
329    
330          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
331    
332  #               $TAG=$self->Read16($fileMST);                  my ($TAG,$POS,$LEN) = unpack("vvv", substr($buff,$i * 6, 6));
 #               $POS=$self->Read16($fileMST);  
 #               $LEN=$self->Read16($fileMST);  
   
                 my ($TAG,$POS,$LEN) = unpack("sss", substr($buff,$i * 6, 6));  
333    
334                  print "TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});                  print STDERR "## TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});
335    
336                  # The TAG does not exists in .FDT so we set it to 0.                  # The TAG does not exists in .FDT so we set it to 0.
337                  #                  #
# Line 340  print ("Error: The MFN:".$mfn." is not f Line 347  print ("Error: The MFN:".$mfn." is not f
347                  push @FieldPOS,$POS;                  push @FieldPOS,$POS;
348                  push @FieldLEN,$LEN;                  push @FieldLEN,$LEN;
349    
350                  $fld_len += $LEN;                  $rec_len += $LEN;
351          }          }
352    
353          # Get Variable Fields          # Get Variable Fields
354    
355          read($self->{'fileMST'},$buff,$fld_len);          read($self->{'fileMST'},$buff,$rec_len);
356    
357            print STDERR "## rec_len: $rec_len poc: ",tell($self->{'fileMST'})."\n" if ($self->{debug});
358    
359          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
360                  # skip zero-sized fields                  # skip zero-sized fields
# Line 353  print ("Error: The MFN:".$mfn." is not f Line 362  print ("Error: The MFN:".$mfn." is not f
362    
363                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);
364          }          }
         close(fileMST);  
365    
366          print Dumper($self) if ($self->{debug});          $self->{'current_mfn'} = $mfn;
367    
368            print STDERR Dumper($self),"\n" if ($self->{debug});
369    
370          return $self->{'record'};          return $self->{'record'};
371  }  }
372    
373  =head2 to_ascii  =head2 to_ascii
374    
375  Dump ascii output of selected MFN  Returns ASCII output of record with specified MFN
376    
377      print $isis->to_ascii(42);
378    
379    This outputs something like this:
380    
381    print $isis->to_ascii(55);    210   ^aNew York^cNew York University press^dcop. 1988
382      990   2140
383      990   88
384      990   HAY
385    
386    If C<read_fdt> is specified when calling C<new> it will display field names
387    from C<.FDT> file instead of numeric tags.
388    
389  =cut  =cut
390    
# Line 378  sub to_ascii { Line 398  sub to_ascii {
398          my $out = "0\t$mfn";          my $out = "0\t$mfn";
399    
400          foreach my $f (sort keys %{$rec}) {          foreach my $f (sort keys %{$rec}) {
401                  $out .= "\n$f\t".join("\n$f\t",@{$self->{record}->{$f}});                  my $fn = $self->tag_name($f);
402                    $out .= "\n$fn\t".join("\n$fn\t",@{$self->{record}->{$f}});
403          }          }
404    
405          $out .= "\n";          $out .= "\n";
# Line 388  sub to_ascii { Line 409  sub to_ascii {
409    
410  =head2 to_hash  =head2 to_hash
411    
412  Read mfn and convert it to hash  Read record with specified MFN and convert it to hash
413    
414    my $hash = $isis->to_hash($mfn);    my $hash = $isis->to_hash($mfn);
415    
416  It has ability to convert characters (using C<hash_filter> from ISIS  It has ability to convert characters (using C<hash_filter>) from ISIS
417  database before creating structures enabling character remapping or quick  database before creating structures enabling character re-mapping or quick
418  fixup of data.  fix-up of data.
419    
420  This function returns hash which is like this:  This function returns hash which is like this:
421    
# Line 413  This function returns hash which is like Line 434  This function returns hash which is like
434               ],               ],
435    };    };
436    
437  You can later use that has to produce any output from ISIS data.  You can later use that hash to produce any output from ISIS data.
438    
439    If database is created using IsisMarc, it will also have to special fields
440    which will be used for identifiers, C<i1> and C<i2> like this:
441    
442      '200' => [
443                 {
444                   'i1' => '1',
445                   'i2' => ' '
446                   'a' => 'Goa',
447                   'f' => 'Valdo D\'Arienzo',
448                   'e' => 'tipografie e tipografi nel XVI secolo',
449                 }
450               ],
451    
452    This method will also create additional field C<000> with MFN.
453    
454  =cut  =cut
455    
# Line 422  sub to_hash { Line 458  sub to_hash {
458    
459          my $mfn = shift || confess "need mfn!";          my $mfn = shift || confess "need mfn!";
460    
461          my $rec;          # init record to include MFN as field 000
462            my $rec = { '000' => [ $mfn ] };
463    
464          my $row = $self->fetch($mfn);          my $row = $self->fetch($mfn);
465    
466          foreach my $k (keys %{$row}) {          foreach my $k (keys %{$row}) {
# Line 431  sub to_hash { Line 469  sub to_hash {
469                          # filter output                          # filter output
470                          $l = $self->{'hash_filter'}->($l) if ($self->{'hash_filter'});                          $l = $self->{'hash_filter'}->($l) if ($self->{'hash_filter'});
471    
                         # has subfields?  
472                          my $val;                          my $val;
473    
474                            # has identifiers?
475                            ($val->{'i1'},$val->{'i2'}) = ($1,$2) if ($l =~ s/^([01 #])([01 #])\^/\^/);
476    
477                            # has subfields?
478                          if ($l =~ m/\^/) {                          if ($l =~ m/\^/) {
479                                  foreach my $t (split(/\^/,$l)) {                                  foreach my $t (split(/\^/,$l)) {
480                                          next if (! $t);                                          next if (! $t);
# Line 449  sub to_hash { Line 491  sub to_hash {
491          return $rec;          return $rec;
492  }  }
493    
494  #  =head2 tag_name
495  # XXX porting from php left-over:  
496  #  Return name of selected tag
497  # do I *REALLY* need those methods, or should I use  
498  # $self->{something} directly?   print $isis->tag_name('200');
499  #  
500  # Probably direct usage is better!  =cut
501  #  
502    sub tag_name {
503            my $self = shift;
504            my $tag = shift || return;
505            return $self->{'TagName'}->{$tag} || $tag;
506    }
507    
508    
509    =head2 read_cnt
510    
511    Read content of C<.CNT> file and return hash containing it.
512    
513      print Dumper($isis->read_cnt);
514    
515  sub TagName {  This function is not used by module (C<.CNT> files are not required for this
516    module to work), but it can be useful to examine your index (while debugging
517    for example).
518    
519    =cut
520    
521    sub read_cnt  {
522          my $self = shift;          my $self = shift;
523          return $self->{TagName};  
524            croak "missing CNT file in ",$self->{isisdb} unless ($self->{cnt_file});
525    
526            # Get the index information from $db.CNT
527      
528            open(my $fileCNT, $self->{cnt_file}) || croak "can't read '$self->{cnt_file}': $!";
529            binmode($fileCNT);
530    
531            my $buff;
532    
533            read($fileCNT, $buff, 26) || croak "can't read first table from CNT: $!";
534            $self->unpack_cnt($buff);
535    
536            read($fileCNT, $buff, 26) || croak "can't read second table from CNT: $!";
537            $self->unpack_cnt($buff);
538    
539            close($fileCNT);
540    
541            return $self->{cnt};
542  }  }
543    
544  sub NextMFN {  =head2 unpack_cnt
545    
546    Unpack one of two 26 bytes fixed length record in C<.CNT> file.
547    
548    Here is definition of record:
549    
550     off key        description                             size
551      0: IDTYPE     BTree type                              s
552      2: ORDN       Nodes Order                             s
553      4: ORDF       Leafs Order                             s
554      6: N          Number of Memory buffers for nodes      s
555      8: K          Number of buffers for first level index s
556     10: LIV        Current number of Index Levels          s
557     12: POSRX      Pointer to Root Record in N0x           l
558     16: NMAXPOS    Next Available position in N0x          l
559     20: FMAXPOS    Next available position in L0x          l
560     24: ABNORMAL   Formal BTree normality indicator        s
561     length: 26 bytes
562    
563    This will fill C<$self> object under C<cnt> with hash. It's used by C<read_cnt>.
564    
565    =cut
566    
567    sub unpack_cnt {
568          my $self = shift;          my $self = shift;
569          return $self->{NXTMFN};  
570            my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);
571    
572            my $buff = shift || return;
573            my @arr = unpack("vvvvvvVVVv", $buff);
574    
575            print STDERR "unpack_cnt: ",join(" ",@arr),"\n" if ($self->{'debug'});
576    
577            my $IDTYPE = shift @arr;
578            foreach (@flds) {
579                    $self->{cnt}->{$IDTYPE}->{$_} = abs(shift @arr);
580            }
581  }  }
582    
583  1;  1;
584    
585  =head1 BUGS  =head1 BUGS
586    
587  This module has been very lightly tested. Use with caution and report bugs.  Some parts of CDS/ISIS documentation are not detailed enough to exmplain
588    some variations in input databases which has been tested with this module.
589    When I was in doubt, I assumed that OpenIsis's implementation was right
590    (except for obvious bugs).
591    
592    However, every effort has been made to test this module with as much
593    databases (and programs that create them) as possible.
594    
595    I would be very greatful for success or failure reports about usage of this
596    module with databases from programs other than WinIsis and IsisMarc. I had
597    tested this against ouput of one C<isis.dll>-based application, but I don't
598    know any details about it's version.
599    
600  =head1 AUTHOR  =head1 AUTHOR
601    
# Line 481  This module has been very lightly tested Line 604  This module has been very lightly tested
604          dpavlin@rot13.org          dpavlin@rot13.org
605          http://www.rot13.org/~dpavlin/          http://www.rot13.org/~dpavlin/
606    
607  This module is based heavily on code from LIBISIS.PHP - Library to read ISIS files V0.1.1  This module is based heavily on code from C<LIBISIS.PHP> library to read ISIS files V0.1.1
608  written in php and (c) 2000 Franck Martin - <franck@sopac.org> released under LGPL.  written in php and (c) 2000 Franck Martin <franck@sopac.org> and released under LGPL.
609    
610  =head1 COPYRIGHT  =head1 COPYRIGHT
611    
# Line 495  LICENSE file included with this module. Line 618  LICENSE file included with this module.
618    
619  =head1 SEE ALSO  =head1 SEE ALSO
620    
621  L<http://www.openisis.org|OpenIsis>, perl(1).  OpenIsis web site L<http://www.openisis.org>
622    
623    perl4lib site L<http://perl4lib.perl.org>
624    
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