--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcoding/number_decode.c	Thu Jun 13 02:29:29 2024 +0000
@@ -0,0 +1,29 @@
+/*
+ * This library module implements the decoding of number (address) digits.
+ */
+
+#include <sys/types.h>
+
+char gsm_address_digits[16] =
+	{'0','1','2','3','4','5','6','7','8','9','*','#','a','b','c','?'};
+
+decode_address_digits(inbuf, outbuf, ndigits)
+	u_char *inbuf;
+	char *outbuf;
+	unsigned ndigits;
+{
+	u_char *inp = inbuf;
+	char *outp = outbuf;
+	unsigned n = 0, b;
+
+	while (n < ndigits) {
+		b = *inp++;
+		*outp++ = gsm_address_digits[b & 0xF];
+		n++;
+		if (n >= ndigits)
+			break;
+		*outp++ = gsm_address_digits[b >> 4];
+		n++;
+	}
+	*outp = '\0';
+}