optionalg
diff --git a/‎codext/binary/excess3.py‎
Lines changed: 16 additions & 4 deletions b/‎codext/binary/excess3.py‎
Lines changed: 16 additions & 4 deletions
@@ -15,6 +15,12 @@
         'This is a test!': ";t7C\x84H6T8D\x83e<\xa3eD\x944D\x84I6`",
         'This is another test ': ";t7C\x84H6T8D\x83e<\xa4CDDICt4DseD\x944D\x84I6P",
     },
+    'dec(excess-3|xs3)': {
+        '\x00':                                            None,
+        '\xff':                                            None,
+        ';t7C\x84H6T8D\x83e<\xa3eD\x944D\x84I6`':          "This is a test!",
+        ';t7C\x84H6T8D\x83e<\xa4CDDICt4DseD\x944D\x84I6P': "This is another test ",
+    },
 }
 
 
@@ -24,6 +30,10 @@
 }
 
 
+class Excess3DecodeError(ValueError):
+    pass
+
+
 def excess3_encode(text, errors="strict"):
     r, bits = "", ""
     for c in text:
@@ -40,13 +50,15 @@ def excess3_encode(text, errors="strict"):
 def excess3_decode(text, errors="strict"):
     code = {v: k for k, v in CODE.items()}
     r, d = "", ""
-    for c in text:
+    for i, c in enumerate(text):
         bin_c = bin(ord(c))[2:].zfill(8)
-        for i in range(0, 8, 4):
+        for k in range(0, 8, 4):
+            hb = bin_c[k:k+4]
             try:
-                d += code[bin_c[i:i+4]]
+                d += code[hb]
             except KeyError:  # (normal case) occurs when 0000 was used for padding
-                break
+                if i != len(text) - 1 or k != 4 or hb != "0000":
+                    d += handle_error("excess3", errors, Excess3DecodeError, decode=True)(hb, i)
             if len(d) == 3:
                 r += chr(int(d))
                 d = ""