Hexdump in Ruby

example.rb

random_twitter_message = (1..140).map{ rand 0xFF }.pack("C*")
hexdump random_twitter_message

# 0000:  af 98 02 2b 25 13 01 42  b8 cd 3a a5 23 07 c2 43  |...+%..B ..:.#..C|
# 0010:  c0 af bd 65 3e a7 c0 4c  26 b9 1e 54 cc c3 5b 3f  |...e>..L &..T..[?|
# 0020:  db d6 86 76 22 d4 31 ab  32 fe b6 32 f4 d4 1c 01  |...v".1. 2..2....|
# 0030:  f6 5d 25 8c 64 9b 18 3a  9d 50 14 a2 86 79 a6 f2  |.]%.d..: .P...y..|
# 0040:  da 50 f3 70 b6 bc e4 76  15 db 2f b7 f6 9c 88 d0  |.P.p...v ../.....|
# 0050:  63 95 23 66 b3 20 f6 ab  62 a6 28 92 c7 6d a9 e0  |c.#f. .. b.(..m..|
# 0060:  1c 2d fe 12 3e fd 8b 95  47 4d b2 14 07 e8 6b 6c  |.-..>... GM....kl|
# 0070:  35 7c ef f3 4a 83 af 9a  cc 0b ce a1 41 c2 f7 b9  |5|..J... ....A...|
# 0080:  2a 6a 85 3e cc e3 a5 9a  f7 dd 2f 17              |*j.>.... ../.    |

hexdump random_twitter_message, width: 8

# 0000:  04 bf 68 fe  de b8 31 8c  |..h. ..1.|
# 0008:  09 e7 31 4e  e6 20 33 78  |..1N . 3x|
# 0010:  c2 60 2c ee  97 27 4d 15  |.`,. .'M.|
# 0018:  4d 47 d6 ae  b0 ef 73 3a  |MG.. ..s:|
# 0020:  da a5 22 0d  18 12 fb f4  |..". ....|
# 0028:  ca 64 4e 43  9c c0 6e 0f  |.dNC ..n.|
# 0030:  47 af 5d cd  fe 66 1d 76  |G.]. .f.v|
# 0038:  21 1f 69 a9  6d 56 e4 88  |!.i. mV..|
# 0040:  66 5a 94 4a  25 fc 69 84  |fZ.J %.i.|
# 0048:  77 39 d7 6a  54 42 4e 49  |w9.j TBNI|
# 0050:  77 fb e5 63  ed ef 1b bf  |w..c ....|
# 0058:  f5 ec 78 98  b8 f5 4b 32  |..x. ..K2|
# 0060:  47 63 2f f0  3e bb 54 2c  |Gc/. >.T,|
# 0068:  11 1c 5b ec  ee e7 51 83  |..[. ..Q.|
# 0070:  1a 02 13 74  44 70 68 ec  |...t Dph.|
# 0078:  58 71 e7 fb  2a ab 12 aa  |Xq.. *...|
# 0080:  df b1 93 ed  d3 fa 26 74  |.... ..&t|
# 0088:  d3 b7 2b 75               |..+u     |

hexdump.rb

def hexdump(str, width: 16)
  bytes = str.unpack("C*")

  w = width/2

  i = 0
  while bytes.size > 0
    a, b = bytes.shift(w), bytes.shift(w)

    h = [a,b].map {|col| col.map{|c| "%02x" % c }.join(" ") }
    c = [a,b].map {|col| col.map{|c| c < 0x20 || c > 0x7E ? '.' : c.chr }.join('') }

    mis = (width - a.size - b.size)
    case mis
    when 1...w
      h[1] << ("   "*mis)
      c[1] << (" "*mis)
    when w...width
      h[0] << "  " << ("   "*(mis-1))
      c[0] << (" "*mis)
    end

    puts "%04x:  %s  %s  |%s %s|" % [i, *h, *c]
    i += width
  end

  str
end