--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcoding/gsmtime_dec.c	Thu Jun 13 02:32:11 2024 +0000
@@ -0,0 +1,27 @@
+/*
+ * This library module implements decoding of GSM timestamps.
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+
+gsm_timestamp_decode(inbuf, outbuf)
+	u_char *inbuf;
+	char *outbuf;
+{
+	u_char rev[7];
+	int i, d1, d2, tzsign;
+
+	for (i = 0; i < 7; i++) {
+		d1 = inbuf[i] & 0xF;
+		d2 = inbuf[i] >> 4;
+		rev[i] = (d1 << 4) | d2;
+	}
+	if (rev[6] & 0x80) {
+		rev[6] &= 0x7F;
+		tzsign = '-';
+	} else
+		tzsign = '+';
+	sprintf(outbuf, "%02X/%02X/%02X,%02X:%02X:%02X%c%02X", rev[0], rev[1],
+		rev[2], rev[3], rev[4], rev[5], tzsign, rev[6]);
+}