Update README.md

Author: kmayerpatel

README.md

@@ -1,2 +1,17 @@
 # COMP590Spring2019-ArithmeticCoder
+
 Arithmetic coder example from class
+
+The text file encoder produces a file with the following format:
+
+* The first 256 * 32 bits are the frequency counts associated with the integer symbol values 0 to 255. 
+  * Each count is a 32 bit value.
+* The next 32 bits are the number of symbols that were encoded
+* The next 8 bits is the value of range_bit_width (i.e., the size of the range registers used by the encoder)
+* Following this are the encoded symbols.
+
+One thing to note that was just touched on at the very end of class is that when the encoding app gets to the end (i.e.,
+it's encoded the last symbol), it needs to have the encoder emit a bit pattern that is known to be between high and low
+so that the decoder doesn't run out of bits as it fills its input buffer when it gets to the end. The method emitMiddle() in
+the encoder does this by writing out a 1 followed by range_bit_width-1 0's since that represents the middle of value of the whole range which is guaranteed to be between high and low.
+