fish

1 files changed, 52 insertions, 0 deletions

diff --git a/dl_docrc.c b/dl_docrc.c
new file mode 100644
index 0000000..18a6cca
--- /dev/null
+++ b/dl_docrc.c
@@ -0,0 +1,52 @@
+/* 
+ * Copyright 1996-2002 - Karl R. Hakimian and David Fries
+ *
+ * This file is part of datalink.
+ *
+ * Datalink is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Datalink is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with datalink (see COPYING); if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+/* crc lookup table */
+static unsigned short int crc16_table[16] = {
+	0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
+	0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
+};
+
+unsigned short int dl_docrc(unsigned char *data)
+{
+	int i;
+	unsigned short int t;
+	unsigned short int crc = 0;
+	int l;
+
+	l = data[0] - 2;
+
+	for (i = 0; i < l; i++)
+	{
+		t = crc16_table[crc & 0xF];
+		crc = (crc >> 4) & 0x0FFF;
+		crc = crc ^ t ^ crc16_table[data[i] & 0xF];
+
+		/* upper 4 bits */
+		t = crc16_table[crc & 0xF];
+		crc = (crc >> 4) & 0x0FFF;
+		crc = crc ^ t ^ crc16_table[(data[i] >> 4) & 0xF];
+	}
+
+	data[l++] = crc >> 8;
+	data[l] = crc & 0xff;
+	return (crc);
+}