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- #------------------------------------------------------------------------------
- # File: BZZ.pm
- #
- # Description: Utility to decode BZZ compressed data
- #
- # Revisions: 09/22/2008 - P. Harvey Created
- #
- # References: 1) http://djvu.sourceforge.net/
- # 2) http://www.djvu.org/
- #
- # Notes: This code based on ZPCodec and BSByteStream of DjVuLibre 3.5.21
- # (see NOTES documentation below for license/copyright details)
- #------------------------------------------------------------------------------
- package Image::ExifTool::BZZ;
- use strict;
- use integer; # IMPORTANT!! use integer arithmetic throughout
- require Exporter;
- use vars qw($VERSION @ISA @EXPORT_OK);
- $VERSION = '1.00';
- @ISA = qw(Exporter);
- @EXPORT_OK = qw(Decode);
- # constants
- sub FREQMAX { 4 }
- sub CTXIDS { 3 }
- sub MAXBLOCK { 4096 }
- # This table has been designed for the ZPCoder
- # by running the following command in file 'zptable.sn':
- # (fast-crude (steady-mat 0.0035 0.0002) 260)))
- my @default_ztable_p = (
- 0x8000, 0x8000, 0x8000, 0x6bbd, 0x6bbd, 0x5d45, 0x5d45, 0x51b9, 0x51b9, 0x4813,
- 0x4813, 0x3fd5, 0x3fd5, 0x38b1, 0x38b1, 0x3275, 0x3275, 0x2cfd, 0x2cfd, 0x2825,
- 0x2825, 0x23ab, 0x23ab, 0x1f87, 0x1f87, 0x1bbb, 0x1bbb, 0x1845, 0x1845, 0x1523,
- 0x1523, 0x1253, 0x1253, 0x0fcf, 0x0fcf, 0x0d95, 0x0d95, 0x0b9d, 0x0b9d, 0x09e3,
- 0x09e3, 0x0861, 0x0861, 0x0711, 0x0711, 0x05f1, 0x05f1, 0x04f9, 0x04f9, 0x0425,
- 0x0425, 0x0371, 0x0371, 0x02d9, 0x02d9, 0x0259, 0x0259, 0x01ed, 0x01ed, 0x0193,
- 0x0193, 0x0149, 0x0149, 0x010b, 0x010b, 0x00d5, 0x00d5, 0x00a5, 0x00a5, 0x007b,
- 0x007b, 0x0057, 0x0057, 0x003b, 0x003b, 0x0023, 0x0023, 0x0013, 0x0013, 0x0007,
- 0x0007, 0x0001, 0x0001, 0x5695, 0x24ee, 0x8000, 0x0d30, 0x481a, 0x0481, 0x3579,
- 0x017a, 0x24ef, 0x007b, 0x1978, 0x0028, 0x10ca, 0x000d, 0x0b5d, 0x0034, 0x078a,
- 0x00a0, 0x050f, 0x0117, 0x0358, 0x01ea, 0x0234, 0x0144, 0x0173, 0x0234, 0x00f5,
- 0x0353, 0x00a1, 0x05c5, 0x011a, 0x03cf, 0x01aa, 0x0285, 0x0286, 0x01ab, 0x03d3,
- 0x011a, 0x05c5, 0x00ba, 0x08ad, 0x007a, 0x0ccc, 0x01eb, 0x1302, 0x02e6, 0x1b81,
- 0x045e, 0x24ef, 0x0690, 0x2865, 0x09de, 0x3987, 0x0dc8, 0x2c99, 0x10ca, 0x3b5f,
- 0x0b5d, 0x5695, 0x078a, 0x8000, 0x050f, 0x24ee, 0x0358, 0x0d30, 0x0234, 0x0481,
- 0x0173, 0x017a, 0x00f5, 0x007b, 0x00a1, 0x0028, 0x011a, 0x000d, 0x01aa, 0x0034,
- 0x0286, 0x00a0, 0x03d3, 0x0117, 0x05c5, 0x01ea, 0x08ad, 0x0144, 0x0ccc, 0x0234,
- 0x1302, 0x0353, 0x1b81, 0x05c5, 0x24ef, 0x03cf, 0x2b74, 0x0285, 0x201d, 0x01ab,
- 0x1715, 0x011a, 0x0fb7, 0x00ba, 0x0a67, 0x01eb, 0x06e7, 0x02e6, 0x0496, 0x045e,
- 0x030d, 0x0690, 0x0206, 0x09de, 0x0155, 0x0dc8, 0x00e1, 0x2b74, 0x0094, 0x201d,
- 0x0188, 0x1715, 0x0252, 0x0fb7, 0x0383, 0x0a67, 0x0547, 0x06e7, 0x07e2, 0x0496,
- 0x0bc0, 0x030d, 0x1178, 0x0206, 0x19da, 0x0155, 0x24ef, 0x00e1, 0x320e, 0x0094,
- 0x432a, 0x0188, 0x447d, 0x0252, 0x5ece, 0x0383, 0x8000, 0x0547, 0x481a, 0x07e2,
- 0x3579, 0x0bc0, 0x24ef, 0x1178, 0x1978, 0x19da, 0x2865, 0x24ef, 0x3987, 0x320e,
- 0x2c99, 0x432a, 0x3b5f, 0x447d, 0x5695, 0x5ece, 0x8000, 0x8000, 0x5695, 0x481a,
- 0x481a, 0, 0, 0, 0, 0
- );
- my @default_ztable_m = (
- 0x0000, 0x0000, 0x0000, 0x10a5, 0x10a5, 0x1f28, 0x1f28, 0x2bd3, 0x2bd3, 0x36e3,
- 0x36e3, 0x408c, 0x408c, 0x48fd, 0x48fd, 0x505d, 0x505d, 0x56d0, 0x56d0, 0x5c71,
- 0x5c71, 0x615b, 0x615b, 0x65a5, 0x65a5, 0x6962, 0x6962, 0x6ca2, 0x6ca2, 0x6f74,
- 0x6f74, 0x71e6, 0x71e6, 0x7404, 0x7404, 0x75d6, 0x75d6, 0x7768, 0x7768, 0x78c2,
- 0x78c2, 0x79ea, 0x79ea, 0x7ae7, 0x7ae7, 0x7bbe, 0x7bbe, 0x7c75, 0x7c75, 0x7d0f,
- 0x7d0f, 0x7d91, 0x7d91, 0x7dfe, 0x7dfe, 0x7e5a, 0x7e5a, 0x7ea6, 0x7ea6, 0x7ee6,
- 0x7ee6, 0x7f1a, 0x7f1a, 0x7f45, 0x7f45, 0x7f6b, 0x7f6b, 0x7f8d, 0x7f8d, 0x7faa,
- 0x7faa, 0x7fc3, 0x7fc3, 0x7fd7, 0x7fd7, 0x7fe7, 0x7fe7, 0x7ff2, 0x7ff2, 0x7ffa,
- 0x7ffa, 0x7fff, 0x7fff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
- );
- my @default_ztable_up = (
- 84, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
- 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
- 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
- 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
- 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81,
- 82, 81, 82, 9, 86, 5, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,
- 82, 99, 76, 101, 70, 103, 66, 105, 106, 107, 66, 109, 60, 111, 56, 69,
- 114, 65, 116, 61, 118, 57, 120, 53, 122, 49, 124, 43, 72, 39, 60, 33,
- 56, 29, 52, 23, 48, 23, 42, 137, 38, 21, 140, 15, 142, 9, 144, 141,
- 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 70, 157, 66, 81, 62, 75,
- 58, 69, 54, 65, 50, 167, 44, 65, 40, 59, 34, 55, 30, 175, 24, 177,
- 178, 179, 180, 181, 182, 183, 184, 69, 186, 59, 188, 55, 190, 51, 192, 47,
- 194, 41, 196, 37, 198, 199, 72, 201, 62, 203, 58, 205, 54, 207, 50, 209,
- 46, 211, 40, 213, 36, 215, 30, 217, 26, 219, 20, 71, 14, 61, 14, 57,
- 8, 53, 228, 49, 230, 45, 232, 39, 234, 35, 138, 29, 24, 25, 240, 19,
- 22, 13, 16, 13, 10, 7, 244, 249, 10, 89, 230, 0, 0, 0, 0, 0
- );
- my @default_ztable_dn = (
- 145, 4, 3, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
- 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
- 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
- 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
- 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77,
- 78, 79, 80, 85, 226, 6, 176, 143, 138, 141, 112, 135, 104, 133, 100, 129,
- 98, 127, 72, 125, 102, 123, 60, 121, 110, 119, 108, 117, 54, 115, 48, 113,
- 134, 59, 132, 55, 130, 51, 128, 47, 126, 41, 62, 37, 66, 31, 54, 25,
- 50, 131, 46, 17, 40, 15, 136, 7, 32, 139, 172, 9, 170, 85, 168, 248,
- 166, 247, 164, 197, 162, 95, 160, 173, 158, 165, 156, 161, 60, 159, 56, 71,
- 52, 163, 48, 59, 42, 171, 38, 169, 32, 53, 26, 47, 174, 193, 18, 191,
- 222, 189, 218, 187, 216, 185, 214, 61, 212, 53, 210, 49, 208, 45, 206, 39,
- 204, 195, 202, 31, 200, 243, 64, 239, 56, 237, 52, 235, 48, 233, 44, 231,
- 38, 229, 34, 227, 28, 225, 22, 223, 16, 221, 220, 63, 8, 55, 224, 51,
- 2, 47, 87, 43, 246, 37, 244, 33, 238, 27, 236, 21, 16, 15, 8, 241,
- 242, 7, 10, 245, 2, 1, 83, 250, 2, 143, 246, 0, 0, 0, 0, 0
- );
- #------------------------------------------------------------------------------
- # New - create new BZZ object
- # Inputs: 0) reference to BZZ object or BZZ class name
- # Returns: blessed BZZ object ref
- sub new
- {
- local $_;
- my $that = shift;
- my $class = ref($that) || $that || 'Image::ExifTool::BZZ';
- return bless {}, $class;
- }
- #------------------------------------------------------------------------------
- # Initialize BZZ object
- # Inputs: 0) BZZ object ref, 1) data ref, 2) true for DjVu compatibility
- sub Init($$)
- {
- my ($self, $dataPt, $djvucompat) = @_;
- # Create machine independent ffz table
- my $ffzt = $$self{ffzt} = [ ];
- my ($i, $j);
- for ($i=0; $i<256; $i++) {
- $$ffzt[$i] = 0;
- for ($j=$i; $j&0x80; $j<<=1) {
- $$ffzt[$i] += 1;
- }
- }
- # Initialize table
- $$self{p} = [ @default_ztable_p ];
- $$self{'m'} = [ @default_ztable_m ];
- $$self{up} = [ @default_ztable_up ];
- $$self{dn} = [ @default_ztable_dn ];
- # Patch table (and lose DjVu compatibility)
- unless ($djvucompat) {
- my ($p, $m, $dn) = ($$self{p}, $$self{'m'}, $$self{dn});
- for ($j=0; $j<256; $j++) {
- my $a = (0x10000 - $$p[$j]) & 0xffff;
- while ($a >= 0x8000) { $a = ($a<<1) & 0xffff }
- if ($$m[$j]>0 && $a+$$p[$j]>=0x8000 && $a>=$$m[$j]) {
- $$dn[$j] = $default_ztable_dn[$default_ztable_dn[$j]];
- }
- }
- }
- $$self{ctx} = [ (0) x 300 ];
- $$self{DataPt} = $dataPt;
- $$self{Pos} = 0;
- $$self{DataLen} = length $$dataPt;
- $$self{a} = 0;
- $$self{buffer} = 0;
- $$self{fence} = 0;
- $$self{blocksize} = 0;
- # Read first 16 bits of code
- if (length($$dataPt) >= 2) {
- $$self{code} = unpack('n', $$dataPt);
- $$self{Pos} += 2;
- } elsif (length($$dataPt) >= 1) {
- $$self{code} = (unpack('C', $$dataPt) << 8) | 0xff;
- $$self{Pos}++;
- } else {
- $$self{code} = 0xffff;
- }
- $$self{byte} = $$self{code} & 0xff;
- # Preload buffer
- $$self{delay} = 25;
- $$self{scount} = 0;
- # Compute initial fence
- $$self{fence} = $$self{code} >= 0x8000 ? 0x7fff : $$self{code};
- }
- #------------------------------------------------------------------------------
- # Decode data block
- # Inputs: 0) optional BZZ object ref, 1) optional data ref
- # Returns: decoded data or undefined on error
- # Notes: If called without a data ref, an input BZZ object ref must be given and
- # the BZZ object must have been initialized by a previous call to Init()
- sub Decode($;$)
- {
- # Decode input stream
- local $_;
- my $self;
- if (ref $_[0] and UNIVERSAL::isa($_[0],'Image::ExifTool::BZZ')) {
- $self = shift;
- } else {
- $self = new Image::ExifTool::BZZ;
- }
- my $dataPt = shift;
- if ($dataPt) {
- $self->Init($dataPt, 1);
- } else {
- $dataPt = $$self{DataPt} or return undef;
- }
- # Decode block size
- my $n = 1;
- my $m = (1 << 24);
- while ($n < $m) {
- my $b = $self->decode_sub(0x8000 + ($$self{a}>>1));
- $n = ($n<<1) | $b;
- }
- $$self{size} = $n - $m;
- return '' unless $$self{size};
- return undef if $$self{size} > MAXBLOCK()*1024;
- # Allocate
- if ($$self{blocksize} < $$self{size}) {
- $$self{blocksize} = $$self{size};
- }
- # Decode Estimation Speed
- my $fshift = 0;
- if ($self->decode_sub(0x8000 + ($$self{a}>>1))) {
- $fshift += 1;
- $fshift += 1 if $self->decode_sub(0x8000 + ($$self{a}>>1));
- }
- # Prepare Quasi MTF
- my @mtf = (0..255);
- my @freq = (0) x FREQMAX();
- my $fadd = 4;
- # Decode
- my $mtfno = 3;
- my $markerpos = -1;
- my $cx = $$self{ctx};
- my ($i, @dat);
- byte: for ($i=0; $i<$$self{size}; $i++) {
- # dummy loop avoids use of "goto" statement
- dummy: for (;;) {
- my $ctxid = CTXIDS() - 1;
- $ctxid = $mtfno if $ctxid > $mtfno;
- my $cp = 0;
- my ($imtf, $bits);
- for ($imtf=0; $imtf<2; ++$imtf) {
- if ($self->decoder($$cx[$cp+$ctxid])) {
- $mtfno = $imtf;
- $dat[$i] = $mtf[$mtfno];
- # (a "goto" here could give a segfault due to a Perl bug)
- last dummy; # do rotation
- }
- $cp += CTXIDS();
- }
- for ($bits=1; $bits<8; ++$bits, $imtf<<=1) {
- if ($self->decoder($$cx[$cp])) {
- my $n = 1;
- my $m = (1 << $bits);
- while ($n < $m) {
- my $b = $self->decoder($$cx[$cp+$n]);
- $n = ($n<<1) | $b;
- }
- $mtfno = $imtf + $n - $m;
- $dat[$i] = $mtf[$mtfno];
- last dummy; # do rotation
- }
- $cp += $imtf;
- }
- $mtfno=256;
- $dat[$i] = 0;
- $markerpos=$i;
- next byte; # no rotation necessary
- }
- # Rotate mtf according to empirical frequencies (new!)
- # Adjust frequencies for overflow
- $fadd = $fadd + ($fadd >> $fshift);
- if ($fadd > 0x10000000) {
- $fadd >>= 24;
- $_ >>= 24 foreach @freq;
- }
- # Relocate new char according to new freq
- my $fc = $fadd;
- $fc += $freq[$mtfno] if $mtfno < FREQMAX();
- my $k;
- for ($k=$mtfno; $k>=FREQMAX(); $k--) {
- $mtf[$k] = $mtf[$k-1];
- }
- for (; $k>0 && $fc>=$freq[$k-1]; $k--) {
- $mtf[$k] = $mtf[$k-1];
- $freq[$k] = $freq[$k-1];
- }
- $mtf[$k] = $dat[$i];
- $freq[$k] = $fc;
- # when "goto" was used, Perl 5.8.6 could segfault here
- # unless "next" was explicitly stated
- }
- #
- # Reconstruct the string
- #
- return undef if $markerpos<1 || $markerpos>=$$self{size};
- # Allocate pointers
- # Prepare count buffer
- my @count = (0) x 256;
- my @posn;
- # Fill count buffer
- no integer;
- for ($i=0; $i<$markerpos; $i++) {
- my $c = $dat[$i];
- $posn[$i] = ($c<<24) | ($count[$c]++ & 0xffffff);
- }
- $posn[$i++] = 0; # (initialize marker entry just to be safe)
- for ( ; $i<$$self{size}; $i++) {
- my $c = $dat[$i];
- $posn[$i] = ($c<<24) | ($count[$c]++ & 0xffffff);
- }
- use integer;
- # Compute sorted char positions
- my $last = 1;
- for ($i=0; $i<256; $i++) {
- my $tmp = $count[$i];
- $count[$i] = $last;
- $last += $tmp;
- }
- # Undo the sort transform
- $i = 0;
- $last = $$self{size}-1;
- while ($last > 0) {
- my $n = $posn[$i];
- no integer;
- my $c = $n >> 24;
- use integer;
- $dat[--$last] = $c;
- $i = $count[$c] + ($n & 0xffffff);
- }
- # Final check and return decoded data
- return undef if $i != $markerpos;
- pop @dat; # (last byte isn't real)
- return pack 'C*', @dat;
- }
- #------------------------------------------------------------------------------
- # Inputs: 0) BZZ object ref, 1) ctx
- # Returns: decoded bit
- sub decoder($$)
- {
- my ($self, $ctx) = @_;
- my $z = $$self{a} + $self->{p}[$ctx];
- if ($z <= $$self{fence}) {
- $$self{a} = $z;
- return ($ctx & 1);
- }
- # must pass $_[1] so subroutine can modify value (darned C++ pass-by-reference!)
- return $self->decode_sub($z, $_[1]);
- }
- #------------------------------------------------------------------------------
- # Inputs: 0) BZZ object ref, 1) z, 2) ctx (or undef)
- # Returns: decoded bit
- sub decode_sub($$;$)
- {
- my ($self, $z, $ctx) = @_;
- # ensure that we have at least 16 bits of encoded data available
- if ($$self{scount} < 16) {
- # preload byte by byte until we have at least 24 bits
- while ($$self{scount} <= 24) {
- if ($$self{Pos} < $$self{DataLen}) {
- $$self{byte} = ord(substr(${$$self{DataPt}}, $$self{Pos}, 1));
- ++$$self{Pos};
- } else {
- $$self{byte} = 0xff;
- if (--$$self{delay} < 1) {
- # setting size to zero forces error return from Decode()
- $$self{size} = 0;
- return 0;
- }
- }
- $$self{buffer} = ($$self{buffer}<<8) | $$self{byte};
- $$self{scount} += 8;
- }
- }
- # Save bit
- my $a = $$self{a};
- my ($bit, $code);
- if (defined $ctx) {
- $bit = ($ctx & 1);
- # Avoid interval reversion
- my $d = 0x6000 + (($z+$a)>>2);
- $z = $d if $z > $d;
- } else {
- $bit = 0;
- }
- # Test MPS/LPS
- if ($z > ($code = $$self{code})) {
- $bit ^= 1;
- # LPS branch
- $z = 0x10000 - $z;
- $a += $z;
- $code += $z;
- # LPS adaptation
- $_[2] = $self->{dn}[$ctx] if defined $ctx;
- # LPS renormalization
- my $sft = $a>=0xff00 ? $self->{ffzt}[$a&0xff] + 8 : $self->{ffzt}[($a>>8)&0xff];
- $$self{scount} -= $sft;
- $$self{a} = ($a<<$sft) & 0xffff;
- $code = (($code<<$sft) & 0xffff) | (($$self{buffer}>>$$self{scount}) & ((1<<$sft)-1));
- } else {
- # MPS adaptation
- $_[2] = $self->{up}[$ctx] if defined $ctx and $a >= $self->{'m'}[$ctx];
- # MPS renormalization
- $$self{scount} -= 1;
- $$self{a} = ($z<<1) & 0xffff;
- $code = (($code<<1) & 0xffff) | (($$self{buffer}>>$$self{scount}) & 1);
- }
- # Adjust fence and save new code
- $$self{fence} = $code >= 0x8000 ? 0x7fff : $code;
- $$self{code} = $code;
- return $bit;
- }
- 1; # end
- __END__
- =head1 NAME
- Image::ExifTool::BZZ - Utility to decode BZZ compressed data
- =head1 SYNOPSIS
- This module is used by Image::ExifTool
- =head1 DESCRIPTION
- This module contains definitions required by Image::ExifTool to decode BZZ
- compressed data in DjVu images.
- =head1 NOTES
- This code is based on ZPCodec and BSByteStream of DjVuLibre 3.5.21 (see
- additional copyrights and the first reference below), which are covered
- under the GNU GPL license.
- This is implemented as Image::ExifTool::BZZ instead of Compress::BZZ because
- I am hoping that someone else will write a proper Compress::BZZ module (with
- compression ability).
- =head1 AUTHOR
- Copyright 2003-2016, Phil Harvey (phil at owl.phy.queensu.ca)
- Copyright 2002, Leon Bottou and Yann Le Cun
- Copyright 2001, AT&T
- Copyright 1999-2001, LizardTech Inc.
- This library is free software; you can redistribute it and/or modify it
- under the same terms as Perl itself.
- =head1 REFERENCES
- =over 4
- =item L<http://djvu.sourceforge.net/>
- =item L<http://www.djvu.org/>
- =back
- =head1 SEE ALSO
- L<Image::ExifTool::DjVu(3pm)|Image::ExifTool::DjVu>,
- L<Image::ExifTool(3pm)|Image::ExifTool>
- =cut
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