added soft Chase decoding for short BCH codes

gives about 1.5dB gain while only half the speed of hard decision.

short_bch_code_encoder.hh

@@ -34,6 +34,12 @@ public:
 	{
 		return (msg << P) | par[msg];
 	}
+	void operator()(int8_t *code, int msg)
+	{
+		int cw = (*this)(msg);
+		for (int i = 0; i < N; ++i)
+			code[i] = 1 - 2 * ((cw >> i) & 1);
+	}
 };
 
 }