--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/enc-text/gsm7.c	Sat Aug 05 02:07:22 2023 +0000
@@ -0,0 +1,78 @@
+/*
+ * In this module we implement SMS encoding in GSM7.
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+#include "defs.h"
+
+extern int utf8_input;
+extern int concat_enable, concat_refno_set;
+extern char msgtext[MAX_MSG_CHARS*2+2];
+extern u_char concat_refno;
+
+gsm7_mode_main()
+{
+	u_char msgtext_gsm7[MAX_MSG_CHARS];
+	unsigned msgtext_gsmlen;
+	int rc;
+	unsigned nparts, n;
+	u_char udh[6];
+	unsigned pos, remain, chunk;
+
+	if (utf8_input && utf8_to_latin1(msgtext) < 0) {
+		fprintf(stderr, "error: invalid UTF-8 message\n");
+		exit(1);
+	}
+	rc = latin1_to_gsm7(msgtext, msgtext_gsm7, MAX_MSG_CHARS,
+				&msgtext_gsmlen);
+	if (rc == -1) {
+		fprintf(stderr, "error: message not valid for GSM7 charset\n");
+		exit(1);
+	}
+	if (rc == -2) {
+		fprintf(stderr, "error: message too long for max concat SMS\n");
+		exit(1);
+	}
+	if (msgtext_gsmlen <= 160) {
+		fputs("dcs 0 septet\nmsg ", stdout);
+		if (msgtext_gsmlen)
+			emit_hex_out(msgtext_gsm7, msgtext_gsmlen, stdout);
+		else
+			fputs("empty", stdout);
+		putchar('\n');
+		exit(0);
+	}
+	if (!concat_enable) {
+		fprintf(stderr, "error: message exceeds 160 chars\n");
+		exit(1);
+	}
+	if (!concat_refno_set)
+		concat_refno = get_concsms_refno_from_host_fs();
+	puts("dcs 0 septet");
+	nparts = (msgtext_gsmlen + 152) / 153;
+	udh[0] = 5;
+	udh[1] = 0x00;
+	udh[2] = 0x03;
+	udh[3] = concat_refno;
+	udh[4] = nparts;
+	pos = 0;
+	remain = msgtext_gsmlen;
+	for (n = 1; n <= nparts; n++) {
+		udh[5] = n;
+		chunk = 153;
+		if (chunk > remain)
+			chunk = remain;
+		fputs("msg-udh ", stdout);
+		emit_hex_out(udh, 6, stdout);
+		emit_hex_out(msgtext_gsm7 + pos, chunk, stdout);
+		putchar('\n');
+		pos += chunk;
+		remain -= chunk;
+	}
+	exit(0);
+}