Implement CRC functions

diff --git a/src/crc13239.c b/src/crc13239.c
new file mode 100644 (file)
index 0000000..cd65441
--- /dev/null
+++ b/src/crc13239.c
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2008, Tollef Fog Heen <tfheen@err.no>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you
+ * may not use this file except in compliance with the License.  You
+ * may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.  See the License for the specific language governing
+ * permissions and limitations under the License.
+ *
+ * ISO 13239 CRC 16 implementation
+ */
+
+#include "crc13239.h"
+
+void crc_init(unsigned short *c) {
+       *c = 0xffff;
+}
+
+void crc_update(unsigned short *c, unsigned char val) {
+       int i, j;
+       m_crc ^= val;
+       for (i = 0; i < 8; i++) {
+               j = m_crc & 1;
+               m_crc >>= 1;
+               if (j) m_crc ^= 0x8408;
+       }
+
+}
+
+unsigned short crc_get_full(unsigned char *data, size_t len, bool onecomp) {
+       unsigned short c;
+       crc_init(&c);
+       while (bcnt--)
+               crc_update(&c, *bp++);
+       return onecomp ? ~c : c;
+}
+
+bool crc_check(unsigned short *c, char *crc) {
+       return (((c & 0xff) == crc[0]) &&
+               ((c >> 8) == crc[1]));
+}

diff --git a/src/crc13239.h b/src/crc13239.h
new file mode 100644 (file)
index 0000000..266a8e0
--- /dev/null
+++ b/src/crc13239.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2008, Tollef Fog Heen <tfheen@err.no>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you
+ * may not use this file except in compliance with the License.  You
+ * may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.  See the License for the specific language governing
+ * permissions and limitations under the License.
+ *
+ */
+
+#ifndef _CRC13239_H
+#define _CRC13239_H
+#define CRC_OK_RESIDUE  0xf0b8
+
+void crc_init(unsigned short *c);
+void crc_update(unsigned short *c, unsigned char *val);
+unsigned short crc_get_full(unsigned char *data, size_t len, bool onecomp);
+bool crc_check(unsigned short *c, char *crc);
+
+#endif /* _CRC13239_H */