implement byte access for some word

wouldn’t have been possible without the ruby version

lib/parfait/word.rb

@@ -94,7 +94,9 @@ module Parfait
       shifted =  char << (rest * 8)
       was = get_internal( word_index )
       was = 0 unless was.is_a?(Numeric)
-      masked = was & [ 0xFFFFFF00 , 0xFFFF00FF , 0xFF00FFFF , 0x00FFFFFF  ][rest]
+      mask = 0xFF << (rest * 8)
+      mask = 0xFFFFFFFF - mask
+      masked = was & mask
       put = masked + shifted
       set_internal( word_index , put )
       msg = "set index=#{index} word_index=#{word_index} rest=#{rest}= "

lib/soml/parfait/word.soml

@@ -1,8 +1,16 @@
 class Word < Object
 
   int char_at(int index)
-    index = index + 2
-    return get_internal(index)
+    int word_index = index - 1
+    word_index = word_index / 4
+    word_index = word_index + 3
+    int rest = index - 1
+    rest = rest.mod(4)
+    int char = get_internal(word_index)
+    int shifted = 8 * rest
+    shifted = char >> shifted
+    int ret = shifted & 255
+    return ret
   end
 
   int set_length(int i)
@@ -10,11 +18,30 @@ class Word < Object
     return i
   end
 
-  Word push_char(int i)
-    int l = self.char_length + 1
-    self.set_length(l)
-    l = l + 2
-    set_internal( l , i)
+  Word push_char(int char)
+    int index = self.char_length + 1
+    self.set_length(index)
+
+    int word_index = index - 1
+    word_index = word_index / 4
+    word_index = word_index + 3
+
+    int rest = index - 1
+    rest = rest.mod(4)
+
+    int shifted =  rest * 8
+    shifted =  char << shifted
+
+    int was = get_internal( word_index )
+    int mask = rest * 8
+    mask = 255 << mask
+    mask = 4294967295 - mask
+
+    int masked = was & mask
+    int put = masked + shifted
+
+    set_internal( word_index , put )
+
     return self
   end
 end

test/parfait/test_word.rb

@@ -23,7 +23,7 @@ HERE
   def test_add_doesnt_change1
     @string_input = <<HERE
 Word w = " "
-w.push_char(32)
+w.push_char(48)
 return w.char_at(1)
 HERE
       check_return 32
@@ -31,11 +31,12 @@ HERE
   def test_after_add_get_works
     @string_input = <<HERE
 Word w = " "
-w.push_char(32)
+w.push_char(48)
 return w.char_at(2)
 HERE
-    check_return 32
+    check_return 48
   end
+
   def test_after_add_length_works
     @string_input = <<HERE
 Word w = " "
@@ -44,4 +45,20 @@ return w.char_length
 HERE
     check_return 2
   end
+
+  def test_get1
+    @string_input = <<HERE
+Word w = "12345"
+return w.char_at(1)
+HERE
+    check_return 49
+  end
+
+  def test_get2
+    @string_input = <<HERE
+Word w = "12345"
+return w.char_at(2)
+HERE
+    check_return 50
+  end
 end