add numerical recipes library

lib/nr/ansi/recipes/hufdec.c

@@ -0,0 +1,26 @@
+
+typedef struct {
+	unsigned long *icod,*ncod,*left,*right,nch,nodemax;
+} huffcode;
+
+void hufdec(unsigned long *ich, unsigned char *code, unsigned long lcode,
+	unsigned long *nb, huffcode *hcode)
+{
+	long nc,node;
+	static unsigned char setbit[8]={0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80};
+
+	node=hcode->nodemax;
+	for (;;) {
+		nc=(*nb >> 3);
+		if (++nc > lcode) {
+			*ich=hcode->nch;
+			return;
+		}
+		node=(code[nc] & setbit[7 & (*nb)++] ?
+			hcode->right[node] : hcode->left[node]);
+		if (node <= hcode->nch) {
+			*ich=node-1;
+			return;
+		}
+	}
+}