programatically fork Tamzen font from Tamsyn 1.8

LICENSE

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+Tamsyn font is free.  You are hereby granted permission to use, copy, modify,
+and distribute it as you see fit.
+
+Tamsyn font is provided "as is" without any express or implied warranty.
+
+The author makes no representations about the suitability of this font for
+a particular purpose.
+
+In no event will the author be held liable for damages arising from the use
+of this font.

README.markdown

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+Tamzen font
+===========
+
+This is [my personal fork][1] of the wonderful [Tamsyn font][2] by Scott Fial.
+It is programatically forked from Tamsyn version 1.8 by the `Tamzen.rb` script
+(needs `gem install grit` library) and diverges from it in the following ways:
+
+* Medium "g" is backported from Tamsyn 1.6.
+* Medium "h" is backported from Tamsyn 1.6.
+* Medium "m" is backported from Tamsyn 1.6.
+* Bold and medium "l" are backported from Tamsyn 1.6.
+* Bold and medium "w" are backported from Tamsyn 1.6.
+* Bold and medium "y" are backported from Tamsyn 1.6.
+* Deliberately empty glyphs are deleted (marked as unimplemented) so that they
+  do not block secondary fonts from supplying real glyphs at those codepoints.
+
+Installation
+------------
+
+Copy the `Tamzen*.bdf` files into your `~/.fonts` directory and run:
+
+    mkfontdir ~/.fonts
+    xset +fp ~/.fonts
+    xset fp rehash
+
+Now you should be able to access the "Tamzen" font family in xfontsel.
+
+License
+-------
+
+Distributed under the same terms as Tamsyn itself.  See `LICENSE` file.
+
+[1]: http://snk.tuxfamily.org/log/tamsyn-1.7b-review.html
+[2]: http://www.fial.com/~scott/tamsyn-font/

Tamzen.rb

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+class Font < Struct.new(:file, :props, :chars)
+  def initialize blob
+    head, *body, @tail = blob.data.split(/(?=\nSTARTCHAR|\nENDFONT)/)
+    props = Hash[head.lines.map {|s| s.chomp.split(' ', 2) }]
+    chars = Hash[body.map {|s| [Integer(s[/ENCODING (\d+)/, 1]), s] }]
+    super blob.name, props, chars
+  end
+
+  def to_s
+    props['CHARS'] = chars.length
+    [
+      props.map {|*a| a.join(' ') }.join("\n"), "\n",
+      chars.values,
+      @tail
+    ].join
+  end
+end
+
+require 'grit'
+GIT = Grit::Repo.new('.')
+GIT.tree('v1.8').blobs.each do |blob|
+  if blob.name =~ /\.bdf$/
+    font = Font.new(blob)
+
+    # delete empty glyphs except space and non-breaking space
+    font.chars.each do |code, char|
+      if code != 32 && code != 160 && char =~ /BITMAP\n(?:00\n)+ENDCHAR/
+        font.chars.delete code
+      end
+    end
+
+    # backport characters from older versions of the font
+    [
+      ['g'.ord, /Medium/, 'v1.6'],
+      ['h'.ord, /Medium/, 'v1.6'],
+      ['m'.ord, /Medium/, 'v1.6'],
+      ['l'.ord, //,       'v1.6'],
+      ['w'.ord, //,       'v1.6'],
+      ['y'.ord, //,       'v1.6'],
+    ].
+    each do |code, weight, version|
+      if font.props['WEIGHT_NAME'] =~ weight
+        old = Font.new(GIT.tree(version)/font.file)
+        font.chars[code] = old.chars[code]
+      end
+    end
+
+    # output the modified font under a different name
+    rename = ['Tamsyn', 'Tamzen']
+    File.write font.file.sub(*rename), font.to_s.gsub(*rename)
+  end
+end