Update decoder state machine diagram to reflect MSB/LSB split

dec_sm.dot

@@ -4,8 +4,10 @@ digraph {
         empty
         input_available
         yield_literal
-        backref_index
-        backref_count
+        backref_index_msb
+        backref_index_lsb
+        backref_count_msb
+        backref_count_lsb
         yield_backref
         check_for_more_input
         done [peripheries=2]
@@ -14,18 +16,29 @@ digraph {
         Start->empty
 
         input_available->yield_literal [label="pop 1-bit"]
-        input_available->backref_index [label="pop 0-bit", weight=10]
+        input_available->backref_index_msb [label="pop 0-bit", weight=10]
+        input_available->backref_index_lsb [label="pop 0-bit, index <8 bits", weight=10]
 
         yield_literal->yield_literal [label="sink()", color="blue"]
         yield_literal->yield_literal [label="poll()", color="red"]
         yield_literal->check_for_more_input [label="poll(), done", color="red"]
         
-        backref_index->backref_count [label="pop M-bit index", weight=10]
-        backref_index->done [label="finish()", color="blue"]
+        backref_index_msb->backref_index_msb [label="sink()", color="blue"]
+        backref_index_msb->backref_index_lsb [label="pop index, upper bits", weight=10]
+        backref_index_msb->done [label="finish()", color="blue"]
 
-        backref_count->backref_count [label="sink()", color="blue"]
-        backref_count->yield_backref [label="pop N-bit count", weight=10]
-        backref_count->done [label="finish()", color="blue"]
+        backref_index_lsb->backref_index_lsb [label="sink()", color="blue"]
+        backref_index_lsb->backref_count_msb [label="pop index, lower bits", weight=10]
+        backref_index_lsb->backref_count_lsb [label="pop index, count <=8 bits", weight=10]
+        backref_index_lsb->done [label="finish()", color="blue"]
+
+        backref_count_msb->backref_count_msb [label="sink()", color="blue"]
+        backref_count_msb->backref_count_lsb [label="pop count, upper bits", weight=10]
+        backref_count_msb->done [label="finish()", color="blue"]
+
+        backref_count_lsb->backref_count_lsb [label="sink()", color="blue"]
+        backref_count_lsb->yield_backref [label="pop count, lower bits", weight=10]
+        backref_count_lsb->done [label="finish()", color="blue"]
 
         yield_backref->yield_backref [label="sink()", color="blue"]
         yield_backref->yield_backref [label="poll()", color="red"]