hex2vga

#!/usr/bin/env ruby
# hex2vga -- Charlotte Koch <dressupgeekout@gmail.com>
#
# This script writes a VGA/EGA ("console") font file to stdout, based on a
# "hex" file as exported by gbdfed(1). I made this because I wanted
# wscons(4) to load Leah Neukirchen's super awesome "sq" font.

begin
  infile = ARGV.shift
  raise ArgumentError if !infile

  in_height = ARGV.shift
  raise ArgumentError if !in_height
  in_height = in_height.to_i

  out_height = ARGV.shift
  raise ArgumentError if !out_height
  out_height = out_height.to_i

  raise ArugmentError if out_height < in_height
rescue
  $stderr.puts("usage: #{File.basename($0)} infile input-height output-height")
  exit 1
end

outarray = []

File.readlines(infile).each do |line|
  line.chomp!
  fields = line.split(":")
  i_16 = fields.first.sub("00", "")
  hex = fields.last

  i = [i_16].pack("H*").unpack("C*").last
  data = [hex].pack("H*")

  outarray[i] = data
end

diff = out_height - in_height

outarray.each do |e|
  if e.nil? or e.empty?
    $stdout.print("\x00" * out_height)
    next
  end

  if diff % 2 == 0
    pad_top = diff/2
    pad_bottom = diff/2
  else
    pad_top = (diff/2) + 1
    pad_bottom = diff/2
  end

  $stdout.print("\x00" * pad_top)
  $stdout.print(e)
  $stdout.print("\x00" * pad_bottom)
end