add numerical recipes library

lib/nr/cpp/recipes/hufdec.cpp

@@ -0,0 +1,25 @@
+#include <string>
+#include "nr.h"
+using namespace std;
+
+void NR::hufdec(unsigned long &ich, string &code, const unsigned long lcode,
+	unsigned long &nb, huffcode &hcode)
+{
+	unsigned long nc;
+	static unsigned char setbit[8]={0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80};
+
+	int node=hcode.nodemax-1;
+	for (;;) {
+		nc=nb >> 3;
+		if (nc >= lcode) {
+			ich=hcode.nch;
+			return;
+		}
+		node=((code[nc] & setbit[7 & nb++]) != 0 ?
+			hcode.right[node] : hcode.left[node]);
+		if (node < hcode.nch) {
+			ich=node;
+			return;
+		}
+	}
+}