path: root/ext/Encode/compile

#!../../perl -w
BEGIN {
    unshift @INC, qw(../../lib ../../../lib);
    $ENV{PATH} .= ';../..;../../..' if $^O eq 'MSWin32';
}
use strict;
use Getopt::Std;
my @orig_ARGV = @ARGV;

# These may get re-ordered.
# RAW is a do_now as inserted by &enter
# AGG is an aggreagated do_now, as built up by &process
use constant {
  RAW_NEXT => 0,
  RAW_IN_LEN => 1,
  RAW_OUT_BYTES => 2,
  RAW_FALLBACK => 3,

  AGG_MIN_IN => 0,
  AGG_MAX_IN => 1,
  AGG_OUT_BYTES => 2,
  AGG_NEXT => 3,
  AGG_IN_LEN => 4,
  AGG_OUT_LEN => 5,
  AGG_FALLBACK => 6,
};
# (See the algorithm in encengine.c - we're building structures for it)

# There are two sorts of structures.
# "do_now" (an array, two variants of what needs storing) is whatever we need
# to do now we've read an input byte.
# It's housed in a "do_next" (which is how we got to it), and in turn points
# to a "do_next" which contains all the "do_now"s for the next input byte.

# There will be a "do_next" which is the start state.
# For a single byte encoding it's the only "do_next" - each "do_now" points
# back to it, and each "do_now" will cause bytes. There is no state.

# For a multi-byte encoding where all characters in the input are the same
# length, then there will be a tree of "do_now"->"do_next"->"do_now"
# branching out from the start state, one step for each input byte.
# The leaf "do_now"s will all be at the same distance from the start state,
# only the leaf "do_now"s cause output bytes, and they in turn point back to
# the start state.

# For an encoding where there are varaible length input byte sequences, you
# will encounter a leaf "do_now" sooner for the shorter input sequences, but
# as before the leaves will point back to the start state.

# The system will cope with escape encodings (imagine them as a mostly
# self-contained tree for each escape state, and cross links between trees
# at the state-switching characters) but so far no input format defines these.

# The system will also cope with having output "leaves" in the middle of
# the bifurcating branches, not just at the extremities, but again no
# input format does this yet.

# There are two variants of the "do_now" structure. The first, smaller variant
# is generated by &enter as the input file is read. There is one structure
# for each input byte. Say we are mapping a single byte encoding to a
# single byte encoding, with  "ABCD" going "abcd". There will be
# 4 "do_now"s, {"A" => [...,"a",...], "B" => [...,"b",...], "C"=>..., "D"=>...}

# &process then walks the tree, building aggregate "do_now" structres for
# adjacent bytes where possible. The aggregate is for a contiguous range of
# bytes which each produce the same length of output, each move to the
# same next state, and each have the same fallback flag.
# So our 4 RAW "do_now"s above become replaced by a single structure
# containing:
# ["A", "D", "abcd", 1, ...]
# ie, for an input byte $_ in "A".."D", output 1 byte, found as
# substr ("abcd", (ord $_ - ord "A") * 1, 1)
# which maps very nicely into pointer arithmetic in C for encengine.c

sub encode_U
{
 # UTF-8 encode long hand - only covers part of perl's range
 ## my $uv = shift;
 # chr() works in native space so convert value from table
 # into that space before using chr().
 my $ch = chr(utf8::unicode_to_native($_[0]));
 # Now get core perl to encode that the way it likes.
 utf8::encode($ch);
 return $ch;
}

sub encode_S
{
 # encode single byte
 ## my ($ch,$page) = @_; return chr($ch);
 return chr $_[0];
}

sub encode_D
{
 # encode double byte MS byte first
 ## my ($ch,$page) = @_; return chr($page).chr($ch);
 return chr ($_[1]) . chr $_[0];
}

sub encode_M
{
 # encode Multi-byte - single for 0..255 otherwise double
 ## my ($ch,$page) = @_;
 ## return &encode_D if $page;
 ## return &encode_S;
 return chr ($_[1]) . chr $_[0] if $_[1];
 return chr $_[0];
}

my %encode_types = (U => \&encode_U,
                    S => \&encode_S,
                    D => \&encode_D,
                    M => \&encode_M,
                   );

# Win32 does not expand globs on command line
eval "\@ARGV = map(glob(\$_),\@ARGV)" if ($^O eq 'MSWin32');

my %opt;
getopts('qOo:f:n:',\%opt);
my $cname = (exists $opt{'o'}) ? $opt{'o'} : shift(@ARGV);
chmod(0666,$cname) if -f $cname && !-w $cname;
open(C,">$cname") || die "Cannot open $cname:$!";


my $dname = $cname;
$dname =~ s/(\.[^\.]*)?$/_def.h/;

my ($doC,$doEnc,$doUcm,$doPet);

if ($cname =~ /\.(c|xs)$/)
 {
  $doC = 1;
  chmod(0666,$dname) if -f $cname && !-w $dname;
  open(D,">$dname") || die "Cannot open $dname:$!";
  my $hname = $cname;
  $hname =~ s/(\.[^\.]*)?$/.h/;
  chmod(0666,$hname) if -f $cname && !-w $hname;
  open(H,">$hname") || die "Cannot open $hname:$!";

  foreach my $fh (\*C,\*D,\*H)
  {
   print $fh <<"END" unless $opt{'q'};
/*
 !!!!!!!   DO NOT EDIT THIS FILE   !!!!!!!
 This file was autogenerated by:
 $^X $0 @orig_ARGV
*/
END
  }

  if ($cname =~ /(\w+)\.xs$/)
   {
    print C "#include <EXTERN.h>\n";
    print C "#include <perl.h>\n";
    print C "#include <XSUB.h>\n";
    print C "#define U8 U8\n";
   }
  print C "#include \"encode.h\"\n";

 }
elsif ($cname =~ /\.enc$/)
 {
  $doEnc = 1;
 }
elsif ($cname =~ /\.ucm$/)
 {
  $doUcm = 1;
 }
elsif ($cname =~ /\.pet$/)
 {
  $doPet = 1;
 }

my @encfiles;
if (exists $opt{'f'})
 {
  # -F is followed by name of file containing list of filenames
  my $flist = $opt{'f'};
  open(FLIST,$flist) || die "Cannot open $flist:$!";
  chomp(@encfiles = <FLIST>);
  close(FLIST);
 }
else
 {
  @encfiles = @ARGV;
 }

my %encoding;
my %strings;
my $saved = 0;
my $subsave = 0;
my $strings = 0;

sub cmp_name
{
 if ($a =~ /^.*-(\d+)/)
  {
   my $an = $1;
   if ($b =~ /^.*-(\d+)/)
    {
     my $r = $an <=> $1;
     return $r if $r;
    }
  }
 return $a cmp $b;
}


foreach my $enc (sort cmp_name @encfiles)
 {
  my ($name,$sfx) = $enc =~ /^.*?([\w-]+)\.(enc|ucm)$/;
  $name = $opt{'n'} if exists $opt{'n'};
  if (open(E,$enc))
   {
    if ($sfx eq 'enc')
     {
      compile_enc(\*E,lc($name));
     }
    else
     {
      compile_ucm(\*E,lc($name));
     }
   }
  else
   {
    warn "Cannot open $enc for $name:$!";
   }
 }

if ($doC)
 {
  print STDERR "Writing compiled form\n";
  foreach my $name (sort cmp_name keys %encoding)
   {
    my ($e2u,$u2e,$erep,$min_el,$max_el) = @{$encoding{$name}};
    output(\*C,$name.'_utf8',$e2u);
    output(\*C,'utf8_'.$name,$u2e);
    push(@{$encoding{$name}},outstring(\*C,$e2u->{Cname}.'_def',$erep));
   }
  foreach my $enc (sort cmp_name keys %encoding)
   {
    my ($e2u,$u2e,$rep,$min_el,$max_el,$rsym) = @{$encoding{$enc}};
    my @info = ($e2u->{Cname},$u2e->{Cname},$rsym,length($rep),$min_el,$max_el);
    my $sym = "${enc}_encoding";
    $sym =~ s/\W+/_/g;
    print C "encode_t $sym = \n";
    print C " {",join(',',@info,"{\"$enc\",(const char *)0}"),"};\n\n";
   }

  foreach my $enc (sort cmp_name keys %encoding)
   {
    my $sym = "${enc}_encoding";
    $sym =~ s/\W+/_/g;
    print H "extern encode_t $sym;\n";
    print D " Encode_XSEncoding(aTHX_ &$sym);\n";
   }

  if ($cname =~ /(\w+)\.xs$/)
   {
    my $mod = $1;
    print C <<'END';

static void
Encode_XSEncoding(pTHX_ encode_t *enc)
{
 dSP;
 HV *stash = gv_stashpv("Encode::XS", TRUE);
 SV *sv    = sv_bless(newRV_noinc(newSViv(PTR2IV(enc))),stash);
 int i = 0;
 PUSHMARK(sp);
 XPUSHs(sv);
 while (enc->name[i])
  {
   const char *name = enc->name[i++];
   XPUSHs(sv_2mortal(newSVpvn(name,strlen(name))));
  }
 PUTBACK;
 call_pv("Encode::define_encoding",G_DISCARD);
 SvREFCNT_dec(sv);
}

END

    print C "\nMODULE = Encode::$mod\tPACKAGE = Encode::$mod\n\n";
    print C "BOOT:\n{\n";
    print C "#include \"$dname\"\n";
    print C "}\n";
   }
  close(D);
  close(H);
  printf STDERR "%d bytes in string tables\n",$strings;
  printf STDERR "%d bytes (%.3g%%) saved spotting duplicates\n",$saved,100*$saved/$strings if $saved;
  printf STDERR "%d bytes (%.3g%%) saved using substrings\n",$subsave,100*$subsave/$strings if $subsave;
 }
elsif ($doEnc)
 {
  foreach my $name (sort cmp_name keys %encoding)
   {
    my ($e2u,$u2e,$erep,$min_el,$max_el) = @{$encoding{$name}};
    output_enc(\*C,$name,$e2u);
   }
 }
elsif ($doUcm)
 {
  foreach my $name (sort cmp_name keys %encoding)
   {
    my ($e2u,$u2e,$erep,$min_el,$max_el) = @{$encoding{$name}};
    output_ucm(\*C,$name,$u2e,$erep,$min_el,$max_el);
   }
 }

close(C);



sub compile_ucm
{
 my ($fh,$name) = @_;
 my $e2u = {};
 my $u2e = {};
 my $cs;
 my %attr;
 while (<$fh>)
  {
   s/#.*$//;
   last if /^\s*CHARMAP\s*$/i;
   if (/^\s*<(\w+)>\s+"?([^"]*)"?\s*$/i) # " # Grrr
    {
     $attr{$1} = $2;
    }
  }
 if (!defined($cs =  $attr{'code_set_name'}))
  {
   warn "No <code_set_name> in $name\n";
  }
 else
  {
   $name = $cs unless exists $opt{'n'};
  }
 my $erep;
 my $urep;
 my $max_el;
 my $min_el;
 if (exists $attr{'subchar'})
  {
   my @byte;
   $attr{'subchar'} =~ /^\s*/cg;
   push(@byte,$1) while $attr{'subchar'} =~ /\G\\x([0-9a-f]+)/icg;
   $erep = join('',map(chr(hex($_)),@byte));
  }
 print "Reading $name ($cs)\n";
 my $nfb = 0;
 my $hfb = 0;
 while (<$fh>)
  {
   s/#.*$//;
   last if /^\s*END\s+CHARMAP\s*$/i;
   next if /^\s*$/;
   my ($u,@byte);
   my $fb = '';
   $u = $1 if (/^<U([0-9a-f]+)>\s+/igc);
   push(@byte,$1) while /\G\\x([0-9a-f]+)/igc;
   $fb = $1 if /\G\s*(\|[0-3])/gc;
   # warn "$_: $u @byte | $fb\n";
   die "Bad line:$_" unless /\G\s*(#.*)?$/gc;
   if (defined($u))
    {
     my $uch = encode_U(hex($u));
     my $ech = join('',map(chr(hex($_)),@byte));
     my $el  = length($ech);
     $max_el = $el if (!defined($max_el) || $el > $max_el);
     $min_el = $el if (!defined($min_el) || $el < $min_el);
     if (length($fb))
      {
       $fb = substr($fb,1);
       $hfb++;
      }
     else
      {
       $nfb++;
       $fb = '0';
      }
     # $fb is fallback flag
     # 0 - round trip safe
     # 1 - fallback for unicode -> enc
     # 2 - skip sub-char mapping
     # 3 - fallback enc -> unicode
     enter($u2e,$uch,$ech,$u2e,$fb+0) if ($fb =~ /[01]/);
     enter($e2u,$ech,$uch,$e2u,$fb+0) if ($fb =~ /[03]/);
    }
   else
    {
     warn $_;
    }
  }
 if ($nfb && $hfb)
  {
   die "$nfb entries without fallback, $hfb entries with\n";
  }
 $encoding{$name} = [$e2u,$u2e,$erep,$min_el,$max_el];
}

sub compile_enc
{
 my ($fh,$name) = @_;
 my $e2u = {};
 my $u2e = {};

 my $type;
 while ($type = <$fh>)
  {
   last if $type !~ /^\s*#/;
  }
 chomp($type);
 return if $type eq 'E';
 # Do the hash lookup once, rather than once per function call. 4% speedup.
 my $type_func = $encode_types{$type};
 my ($def,$sym,$pages) = split(/\s+/,scalar(<$fh>));
 warn "$type encoded $name\n";
 my $rep = '';
 # Save a defined test by setting these to defined values.
 my $min_el = ~0; # A very big integer
 my $max_el = 0;  # Anything must be longer than 0
 {
  my $v = hex($def);
  $rep = &$type_func($v & 0xFF, ($v >> 8) & 0xffe);
 }
 my %seen;
 do
  {
   my $line = <$fh>;
   chomp($line);
   my $page = hex($line);
   my $ch = 0;
   my $i = 16;
   do
    {
     # So why is it 1% faster to leave the my here?
     my $line = <$fh>;
     die "Line should be exactly 65 characters long including newline"
       unless length ($line) == 65;
     # Split line into groups of 4 hex digits, convert groups to ints
     # This takes 65.35		
     # map {hex $_} $line =~ /(....)/g
     # This takes 63.75 (2.5% less time)
     # unpack "n*", pack "H*", $line
     # There's an implicit loop in map. Loops are bad, m'kay. Ops are bad, m'kay
     # Doing it as while ($line =~ /(....)/g) took 74.63
     foreach my $val (unpack "n*", pack "H*", $line)
      {
       next if $val == 0xFFFD;
       my $ech = &$type_func($ch,$page);
       if ($val || (!$ch && !$page))
        {
         my $el  = length($ech);
         $max_el = $el if $el > $max_el;
         $min_el = $el if $el < $min_el;
         my $uch = encode_U($val);
         # We don't need to read this quickly, so storing it as a scalar,
         # rather than 3 (anon array, plus the 2 scalars it holds) saves
         # RAM and may make us faster on low RAM systems. [see __END__]
         if (exists $seen{$uch})
          {
           warn sprintf("U%04X is %02X%02X and %04X\n",
                        $val,$page,$ch,$seen{$uch});
          }
         else
          {
           $seen{$uch} = $page << 16 | $ch;
          }
         # Passing 2 extra args each time is 3.6% slower!
         # Even with having to add $fallback ||= 0 later
         enter_fb0($e2u,$ech,$uch);
         enter_fb0($u2e,$uch,$ech);
        }
       else
        {
         # No character at this position
         # enter($e2u,$ech,undef,$e2u);
        }
       $ch++;
      }
    } while --$i;
  } while --$pages;
 die "\$min_el=$min_el, \$max_el=$max_el - seems we read no lines"
   if $min_el > $max_el;
 $encoding{$name} = [$e2u,$u2e,$rep,$min_el,$max_el];
}

# my ($a,$s,$d,$t,$fb) = @_;
sub enter {
  my ($current,$inbytes,$outbytes,$next,$fallback) = @_;
  # state we shift to after this (multibyte) input character defaults to same
  # as current state.
  $next ||= $current;
  # Making sure it is defined seems to be faster than {no warnings;} in
  # &process, or passing it in as 0 explicity.
  # XXX $fallback ||= 0;

  # Start at the beginning and work forwards through the string to zero.
  # effectively we are removing 1 character from the front each time
  # but we don't actually edit the string. [this alone seems to be 14% speedup]
  # Hence -$pos is the length of the remaining string.
  my $pos = -length $inbytes;
  while (1) {
    my $byte = substr $inbytes, $pos, 1;
    #  RAW_NEXT => 0,
    #  RAW_IN_LEN => 1,
    #  RAW_OUT_BYTES => 2,
    #  RAW_FALLBACK => 3,
    # to unicode an array would seem to be better, because the pages are dense.
    # from unicode can be very sparse, favouring a hash.
    # hash using the bytes (all length 1) as keys rather than ord value,
    # as it's easier to sort these in &process.

    # It's faster to always add $fallback even if it's undef, rather than
    # choosing between 3 and 4 element array. (hence why we set it defined
    # above)
    my $do_now = $current->{Raw}{$byte} ||= [{},-$pos,'',$fallback];
    # When $pos was -1 we were at the last input character.
    unless (++$pos) {
      $do_now->[RAW_OUT_BYTES] = $outbytes;
      $do_now->[RAW_NEXT] = $next;
      return;
    }
    # Tail recursion. The intermdiate state may not have a name yet.
    $current = $do_now->[RAW_NEXT];
  }
}

# This is purely for optimistation. It's just &enter hard coded for $fallback
# of 0, using only a 3 entry array ref to save memory for every entry.
sub enter_fb0 {
  my ($current,$inbytes,$outbytes,$next) = @_;
  $next ||= $current;

  my $pos = -length $inbytes;
  while (1) {
    my $byte = substr $inbytes, $pos, 1;
    my $do_now = $current->{Raw}{$byte} ||= [{},-$pos,''];
    unless (++$pos) {
      $do_now->[RAW_OUT_BYTES] = $outbytes;
      $do_now->[RAW_NEXT] = $next;
      return;
    }
    $current = $do_now->[RAW_NEXT];
  }
}


sub outstring
{
 my ($fh,$name,$s) = @_;
 my $sym = $strings{$s};
 if ($sym)
  {
   $saved += length($s);
  }
 else
  {
   if ($opt{'O'}) {
       foreach my $o (keys %strings)
        {
         next unless (my $i = index($o,$s)) >= 0;
         $sym = $strings{$o};
         $sym .= sprintf("+0x%02x",$i) if ($i);
         $subsave += length($s);
         return $strings{$s} = $sym;
       }
   }
   $strings{$s} = $sym = $name;
   $strings += length($s);
   my $definition = sprintf "static const U8 %s[%d] = { ",$name,length($s);
   # Maybe we should assert that these are all <256.
   $definition .= join(',',unpack "C*",$s);
   # We have a single long line. Split it at convenient commas.
   $definition =~ s/(.{74,77},)/$1\n/g;
   print $fh "$definition };\n\n";
  }
 return $sym;
}

sub process
{
  my ($name,$a) = @_;
  $name =~ s/\W+/_/g;
  $a->{Cname} = $name;
  my $raw = $a->{Raw};
  my ($l, $agg_max_in, $agg_next, $agg_in_len, $agg_out_len, $agg_fallback);
  my @ent;
  $agg_max_in = 0;
  foreach my $key (sort keys %$raw) {
    #  RAW_NEXT => 0,
    #  RAW_IN_LEN => 1,
    #  RAW_OUT_BYTES => 2,
    #  RAW_FALLBACK => 3,
    my ($next, $in_len, $out_bytes, $fallback) = @{$raw->{$key}};
    # Now we are converting from raw to aggregate, switch from 1 byte strings
    # to numbers
    my $b = ord $key;
    $fallback ||= 0;
    if ($l &&
        # If this == fails, we're going to reset $agg_max_in below anyway.
        $b == ++$agg_max_in &&
        # References in numeric context give the pointer as an int.
        $agg_next == $next &&
        $agg_in_len == $in_len &&
        $agg_out_len == length $out_bytes &&
        $agg_fallback == $fallback
        # && length($l->[AGG_OUT_BYTES]) < 16
       ) {
      #     my $i = ord($b)-ord($l->[AGG_MIN_IN]);
      # we can aggregate this byte onto the end.
      $l->[AGG_MAX_IN] = $b;
      $l->[AGG_OUT_BYTES] .= $out_bytes;
    } else {
      # AGG_MIN_IN => 0,
      # AGG_MAX_IN => 1,
      # AGG_OUT_BYTES => 2,
      # AGG_NEXT => 3,
      # AGG_IN_LEN => 4,
      # AGG_OUT_LEN => 5,
      # AGG_FALLBACK => 6,
      # Reset the last thing we saw, plus set 5 lexicals to save some derefs.
      # (only gains .6% on euc-jp  -- is it worth it?)
      push @ent, $l = [$b, $agg_max_in = $b, $out_bytes, $agg_next = $next,
                       $agg_in_len = $in_len, $agg_out_len = length $out_bytes,
                       $agg_fallback = $fallback];
    }
    if (exists $next->{Cname}) {
      $next->{'Forward'} = 1 if $next != $a;
    } else {
      process(sprintf("%s_%02x",$name,$b),$next);
    }
  }
  # encengine.c rules say that last entry must be for 255
  if ($agg_max_in < 255) {
    push @ent, [1+$agg_max_in, 255,undef,$a,0,0];
  }
  $a->{'Entries'} = \@ent;
}

sub outtable
{
 my ($fh,$a) = @_;
 my $name = $a->{'Cname'};
 # String tables
 foreach my $b (@{$a->{'Entries'}})
  {
   next unless $b->[AGG_OUT_LEN];
   my $s = $b->[AGG_MIN_IN];
   my $e = $b->[AGG_MAX_IN];
   outstring($fh,sprintf("%s__%02x_%02x",$name,$s,$e),$b->[AGG_OUT_BYTES]);
  }
 if ($a->{'Forward'})
  {
   print $fh "\nstatic encpage_t $name\[",scalar(@{$a->{'Entries'}}),"];\n";
  }
 $a->{'Done'} = 1;
 foreach my $b (@{$a->{'Entries'}})
  {
   my ($s,$e,$out,$t,$end,$l) = @$b;
   outtable($fh,$t) unless $t->{'Done'};
  }
 print $fh "\nstatic encpage_t $name\[",scalar(@{$a->{'Entries'}}),"] = {\n";
 foreach my $b (@{$a->{'Entries'}})
  {
   my ($sc,$ec,$out,$t,$end,$l,$fb) = @$b;
   $end |= 0x80 if $fb;
   print  $fh "{";
   if ($l)
    {
     printf $fh outstring($fh,'',$out);
    }
   else
    {
     print  $fh "0";
    }
   print  $fh ",",$t->{Cname};
   printf $fh ",0x%02x,0x%02x,$l,$end},\n",$sc,$ec;
  }
 print $fh "};\n";
}

sub output
{
 my ($fh,$name,$a) = @_;
 process($name,$a);
 # Sub-tables
 outtable($fh,$a);
}

sub output_enc
{
 my ($fh,$name,$a) = @_;
 die "Changed - fix me for new structure";
 foreach my $b (sort keys %$a)
  {
   my ($s,$e,$out,$t,$end,$l,$fb) = @{$a->{$b}};
  }
}

sub decode_U
{
 my $s = shift;
}

my @uname;
sub char_names
{
 my $s = do "unicore/Name.pl";
 die "char_names: unicore/Name.pl: $!\n" unless defined $s;
 pos($s) = 0;
 while ($s =~ /\G([0-9a-f]+)\t([0-9a-f]*)\t(.*?)\s*\n/igc)
  {
   my $name = $3;
   my $s = hex($1);
   last if $s >= 0x10000;
   my $e = length($2) ? hex($2) : $s;
   for (my $i = $s; $i <= $e; $i++)
    {
     $uname[$i] = $name;
#    print sprintf("U%04X $name\n",$i);
    }
  }
}

sub output_ucm_page
{
 my ($cmap,$a,$t,$pre) = @_;
 # warn sprintf("Page %x\n",$pre);
 foreach my $b (sort keys %$t)
  {
    die "Changed - fix me for new structure";
   my ($s,$e,$out,$n,$end,$l,$fb) = @{$t->{$b}};
   die "oops $s $e" unless $s eq $e;
   my $u = ord($s);
   if ($n != $a && $n != $t)
    {
     output_ucm_page($cmap,$a,$n,(($pre|($u &0x3F)) << 6)&0xFFFF);
    }
   elsif (length($out))
    {
     if ($pre)
      {
       $u = $pre|($u &0x3f);
      }
     my $s = sprintf "<U%04X> ",$u;
     foreach my $c (split(//,$out))
      {
       $s .= sprintf "\\x%02X",ord($c);
      }
     $s .= sprintf " |%d # %s\n",($fb ? 1 : 0),$uname[$u];
     push(@$cmap,$s);
    }
   else
    {
     warn join(',',@{$t->{$b}},$a,$t);
    }
  }
}

sub output_ucm
{
 my ($fh,$name,$h,$rep,$min_el,$max_el) = @_;
 print $fh "# $0 @orig_ARGV\n" unless $opt{'q'};
 print $fh "<code_set_name> \"$name\"\n";
 char_names();
 if (defined $min_el)
  {
   print $fh "<mb_cur_min> $min_el\n";
  }
 if (defined $max_el)
  {
   print $fh "<mb_cur_max> $max_el\n";
  }
 if (defined $rep)
  {
   print $fh "<subchar> ";
   foreach my $c (split(//,$rep))
    {
     printf $fh "\\x%02X",ord($c);
    }
   print $fh "\n";
  }
 my @cmap;
 output_ucm_page(\@cmap,$h,$h,0);
 print $fh "#\nCHARMAP\n";
 foreach my $line (sort { substr($a,8) cmp substr($b,8) } @cmap)
  {
   print $fh $line;
  }
 print $fh "END CHARMAP\n";
}


__END__
With %seen holding array refs:

      865.66 real        28.80 user         8.79 sys
      7904  maximum resident set size
      1356  average shared memory size
     18566  average unshared data size
       229  average unshared stack size
     46080  page reclaims
     33373  page faults

With %seen holding simple scalars:

      342.16 real        27.11 user         3.54 sys
      8388  maximum resident set size
      1394  average shared memory size
     14969  average unshared data size
       236  average unshared stack size
     28159  page reclaims
      9839  page faults

Yes, 5 minutes is faster than 15. Above is for CP936 in CN. Only difference is
how %seen is storing things its seen. So it is pathalogically bad on a 16M
RAM machine, but it's going to help even on modern machines.
Swapping is bad, m'kay :-)