The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Monday, January 23, 2012

99 ways to program a hex, Part 15: Lua

I'm still taking a break from C, and today's version is in Lua.

#!/usr/bin/env lua
-- ***************************************************************
--
-- Copyright 2012 by Sean Conner.  All Rights Reserved.
-- 
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.
--
-- Comments, questions and criticisms can be sent to: sean@conman.org
--
-- ********************************************************************

-- Style: Lua 5.1

function do_dump(fpin,fpout)
  local offset = 0

  while true do
    local line = fpin:read(16)
    if line == nil then return end
      fpout:write(
    	string.format("%08X: ",offset),
        line:gsub(".",function(c) return string.format("%02X ",c:byte()) end),
    	string.rep(" ",3 * (16 - line:len())),
    	line:gsub("%c","."),
    	"\n"
      )
    offset = offset + 16
  end
end

-- **********************************************************************

if #arg == 0 then
  print("-----stdin-----")
  do_dump(io.stdin,io.stdout)
else
  for i = 1 , #arg do
    local f = io.open(arg[1],"r")
    io.stdout:write("-----",arg[1],"-----","\n")
    do_dump(f,io.stdout)
    f:close()
  end
end

os.exit(0)

What I'm noticing (besides my text editor's horrible attempts at syntax highlighting in this entry) is that the non-C versions are quite a bit shorter than the C versions. I'm sure part of that reason is the high level of abstraction obtained by not using C. For instance, in this version, the code to dump the data is easily half the length of the shortest C version, thanks to the clever string.gsub() routine in Lua.

Obligatory Picture

[It's the most wonderful time of the year!]

Obligatory Links

Obligatory Miscellaneous

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The dates are the permanent links to that day's entries (or entry, if there is only one entry). The titles are the permanent links to that entry only. The format for the links are simple: Start with the base link for this site: http://boston.conman.org/, then add the date you are interested in, say 2000/08/01, so that would make the final URL:

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