Module: Gruesome::Z::ZSCII

Defined in:
lib/gruesome/z/zscii.rb

Overview

This translates between the special ZSCII character encoding to ASCII / UNICODE

Constant Summary collapse

ALPHABET_TABLES = 
[
  "abcdefghijklmnopqrstuvwxyz", 
  "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 
  " \n0123456789.,!?_#'\"/\\-:()"
]
V1_A2 = 
" 0123456789.,!?_#'\"/\\<-:()"
UNICODE_TRANSLATION_TABLE = 
{
  155 => "\u00e4", 156 => "\u00f6", 157 => "\u00fc", 158 => "\u00c4", 159 => "\u00d6", 
  160 => "\u00dc", 161 => "\u00df", 162 => "\u00bb", 163 => "\u00ab", 164 => "\u00eb", 
  165 => "\u00ef", 166 => "\u00ff", 167 => "\u00cb", 168 => "\u00cf", 169 => "\u00e1",
  170 => "\u00e9", 171 => "\u00ed", 172 => "\u00f3", 173 => "\u00fa", 174 => "\u00fd",
  175 => "\u00c1", 176 => "\u00c9", 177 => "\u00cd", 178 => "\u00d3", 179 => "\u00da",
  180 => "\u00dd", 181 => "\u00e0", 182 => "\u00e8", 183 => "\u00ec", 184 => "\u00f2",
  185 => "\u00f9", 186 => "\u00c0", 187 => "\u00c8", 188 => "\u00cc", 189 => "\u00d2",
  190 => "\u00d9", 191 => "\u00e2", 192 => "\u00ea", 193 => "\u00ee", 194 => "\u00f4",
  195 => "\u00fb", 196 => "\u00c2", 197 => "\u00ca", 198 => "\u00ce", 199 => "\u00d4",
  200 => "\u00db", 201 => "\u00e5", 202 => "\u00c5", 203 => "\u00f8", 204 => "\u00d8",
  205 => "\u00e3", 206 => "\u00f1", 207 => "\u00f5", 208 => "\u00c3", 209 => "\u00d1",
  210 => "\u00d5", 211 => "\u00e6", 212 => "\u00c6", 213 => "\u00e7", 214 => "\u00c7",
  215 => "\u00fe", 216 => "\u00f0", 217 => "\u00de", 218 => "\u00d0", 219 => "\u00a3",
  220 => "\u0153", 221 => "\u0152", 222 => "\u00a1", 223 => "\u00bf" 
}

Class Method Summary collapse

Class Method Details

.encode(string, version) ⇒ Object 



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# File 'lib/gruesome/z/zscii.rb', line 215

def ZSCII.encode(string, version)
  codes = []
  string.each_char do |chr|
    subcodes = ZSCII.translate_char(chr, version)
    subcodes.each do |code|
      codes << code
    end
  end

  # pad codes to be divisible by three
  # and pad with '5' shift code
  (codes.length % 3).times do 
    codes << 5
  end
  
  # encode the z-codes
  words = []

  word = 0
  codes.each_with_index do |code, i|
    if (i % 3) == 0
      word = (code & 0b11111) << 10
    elsif (i % 3) == 1
      word |= (code & 0b11111) << 5
    else
      word |= code & 0b11111
      words << word
    end
  end

  # Give single that it is the last word
  words[-1] |= 0b10000000_00000000

  words
end

.encode_to_zchars(string, version) ⇒ Object 



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# File 'lib/gruesome/z/zscii.rb', line 206

def ZSCII.encode_to_zchars(string, version)
  codes = []
  string.each_char do |chr|
    codes << ZSCII.translate_char_to_zchar(chr, version)
  end

  codes
end

.eval_alphabet(initial_alphabet, version, codes) ⇒ Object

figure out if a shift lock is pressed and return it



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# File 'lib/gruesome/z/zscii.rb', line 34

def ZSCII.eval_alphabet(initial_alphabet, version, codes)
  if version < 3
  else
    initial_alphabet
  end
end

.translate(initial_alphabet, version, zscii_str, abbreviation_table = nil, table = nil) ⇒ Object

return the utf8 string for the given ZSCII code



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# File 'lib/gruesome/z/zscii.rb', line 252

def ZSCII.translate(initial_alphabet, version, zscii_str, abbreviation_table = nil, table = nil)
  str = ""

  alphabet = initial_alphabet

  # for abbreviations
  next_is_abbrev = false
  abbrev_alphabet = 0

  # for 10-bit characters
  next_is_big_char_top = false
  next_is_big_char_bottom = false
  big_char = 0

  zscii_str.each do |c|
    if next_is_big_char_top
      next_is_big_char_top = false
      next_is_big_char_bottom = true

      big_char = c
    elsif next_is_big_char_bottom
      next_is_big_char_bottom = false

      big_char = big_char << 5
      big_char |= c

      str += translate_Zchar(big_char)
    elsif next_is_abbrev
      next_is_abbrev = false

      str += abbreviation_table.lookup(abbrev_alphabet, c, 0)
    elsif (version < 3 and c == 2) or c == 4
      # handle shift characters
      alphabet = (alphabet + 1) % 3
      if version < 3 and c == 2
        initial_alphabet = alphabet
      end
    elsif (version < 3 and c == 3) or c == 5
      # handle shift characters
      alphabet = (alphabet - 1) % 3
      if version < 3 and c == 3
        initial_alphabet = alphabet
      end
    elsif (version >= 2 and c == 1) or (version >= 3 and (c == 2 or c == 3))
      # the next code will decide the character to pull from the table
      if abbreviation_table != nil
        next_is_abbrev = true
        abbrev_alphabet = c - 1
      end
    else
      # translate character
      if alphabet == 2 and c == 6
        # 10 bit ZSCII code follows
        # next c gives top 5 bits
        # c after that gives bottom 5 bits
        next_is_big_char_top = true
      elsif c == 0 
        # space
        str += " "
      elsif version == 1 and c == 1
        # newline
        str += "\n"
      elsif version == 1 and alphabet == 2
        alphabet_char_idx = c - 6
        str += V1_A2[alphabet_char_idx]
      elsif version <= 4 or table == nil
        # normal translation
        # c will always be > 5 here
        alphabet_char_idx = c - 6
        str += ALPHABET_TABLES[alphabet][alphabet_char_idx]
      elsif version >= 5
        # table is not nil, use it to determine the letter
        # XXX: Use included table (array of three strings)
      end
    end

    if c < 2 or c > 5
      alphabet = initial_alphabet
    end
  end

  return str
end

.translate_char(chr, version) ⇒ Object

Give array of Z-codes



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# File 'lib/gruesome/z/zscii.rb', line 71

def ZSCII.translate_char(chr, version)
  ret = []
  if chr >= 'a'[0] and chr <= 'z'[0]
    # A0
    chr = chr.getbyte(0) - 'a'.getbyte(0)
    chr += 6
    ret << chr
  elsif chr >= 'A'[0] and chr <= 'Z'[0]
    # A1
    chr = chr.getbyte(0) - 'A'.getbyte(0)
    chr += 6

    ret << 4
    ret << chr
  elsif chr == " "
    ret << 0
  elsif chr == "\n"
    if version == 1
      # use 10-bit code since newline is not in the alphabet 2
      ret << 5
      ret << 6
      ret << 0
      ret << 13
    else
      ret << 5
      ret << 7
    end
  elsif chr >= '0'[0] and chr <= '9'[0]
    chr = chr[0] - '0'[0]
    if version == 1
      chr += 7
    else
      chr += 8
    end
    ret << 5
    ret << chr
  elsif chr == "."
    ret << 5
    if version == 1
      ret << 17
    else
      ret << 18
    end
  elsif chr == ","
    ret << 5
    if version == 1
      ret << 18
    else  
      ret << 19
    end
  elsif chr == "!"
    ret << 5
    if version == 1
      ret << 19
    else
      ret << 20
    end
  elsif chr == "?"
    ret << 5
    if version == 1
      ret << 20
    else
      ret << 21
    end
  elsif chr == "_"
    ret << 5
    if version == 1
      ret << 21
    else
      ret << 22
    end
  elsif chr == "#"
    ret << 5
    if version == 1
      ret << 22
    else
      ret << 23
    end
  elsif chr == "'"
    ret << 5
    if version == 1
      ret << 23
    else
      ret << 24
    end
  elsif chr == "\""
    ret << 5
    if version == 1
      ret << 24
    else
      ret << 25
    end
  elsif chr == "/"
    ret << 5
    if version == 1
      ret << 25
    else
      ret << 26
    end
  elsif chr == "\\"
    ret << 5
    if version == 1
      ret << 26
    else
      ret << 27
    end
  elsif chr == "<"
    if version == 1
      ret << 5
      ret << 27
    else
      # use 10-bit
      ret << 5
      ret << 6
      ret << 0
      ret << '<'[0]
    end
  elsif chr == "-"
    ret << 5
    ret << 28
  elsif chr == ":"
    ret << 5
    ret << 29
  elsif chr == "("
    ret << 5
    ret << 30
  elsif chr == ")"
    ret << 5
    ret << 30
  end
  # TODO: Unicode

  ret
end

.translate_char_to_zchar(chr, version) ⇒ Object 



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# File 'lib/gruesome/z/zscii.rb', line 55

def ZSCII.translate_char_to_zchar(chr, version)
  if chr == "\t"
    9
  elsif chr == " "
    11
  elsif chr == "\n"
    13
  elsif chr.getbyte(0) >= 32 and chr.getbyte(0) <= 126
    chr.getbyte(0)
  else
    # XXX: Unicode Translation Table reversed
    "?".getbyte(0)
  end 
end

.translate_Zchar(zchar) ⇒ Object 



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# File 'lib/gruesome/z/zscii.rb', line 41

def ZSCII.translate_Zchar(zchar)
  if zchar == 9
    "\t"
  elsif zchar == 11 
    " "
  elsif zchar == 13
    "\n"
  elsif zchar >= 32 and zchar <= 126
    zchar.chr
  elsif zchar >= 155 and zchar <= 223
    UNICODE_TRANSLATION_TABLE[zchar]
  end
end