lib: Add CRC-8 and CRC-16 checksums

These checksum will be handy for header checksums.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

3 files changed, 88 insertions, 0 deletions

diff --git a/include/ouroboros/crc16.h b/include/ouroboros/crc16.h
new file mode 100644
index 00000000..df4d4f57
--- /dev/null
+++ b/include/ouroboros/crc16.h
@@ -0,0 +1,43 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2026
+ *
+ * 16-bit Cyclic Redundancy Check (CCITT-FALSE variant)
+ *
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+/*
+ * Polynomial: ITU-T V.41 / CCITT-FALSE, CRC-16/IBM-3740.
+ *   reveng catalog: https://reveng.sourceforge.io/crc-catalogue
+ *
+ * Intended for medium-size header check sequences (typ. <= 4 KiB).
+ * Hamming distance HD=4 up to 32751 message bits.
+ */
+
+#ifndef OUROBOROS_LIB_CRC16_H
+#define OUROBOROS_LIB_CRC16_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define CRC16_HASH_LEN 2
+
+void crc16_ccitt_false(uint16_t *   crc,
+                       const void * buf,
+                       size_t       len);
+
+#endif /* OUROBOROS_LIB_CRC16_H */
diff --git a/include/ouroboros/crc8.h b/include/ouroboros/crc8.h
new file mode 100644
index 00000000..97502a25
--- /dev/null
+++ b/include/ouroboros/crc8.h
@@ -0,0 +1,43 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2026
+ *
+ * 8-bit Cyclic Redundancy Check (AUTOSAR variant)
+ *
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+/*
+ * Polynomial: AUTOSAR SWS_CRC, CRC-8/AUTOSAR.
+ *   reveng catalog: https://reveng.sourceforge.io/crc-catalogue
+ *
+ * Intended for short header check sequences (typ. <= 32 bytes).
+ * Hamming distance HD=4 up to 119 message bits, HD=3 up to 247.
+ */
+
+#ifndef OUROBOROS_LIB_CRC8_H
+#define OUROBOROS_LIB_CRC8_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define CRC8_HASH_LEN 1
+
+void crc8_autosar(uint8_t *    crc,
+                  const void * buf,
+                  size_t       len);
+
+#endif /* OUROBOROS_LIB_CRC8_H */
diff --git a/include/ouroboros/hash.h b/include/ouroboros/hash.h
index c7b3d5f6..17ab98ac 100644
--- a/include/ouroboros/hash.h
+++ b/include/ouroboros/hash.h
@@ -39,6 +39,8 @@ enum hash_algo {
         HASH_CRC32,
         HASH_MD5,
         HASH_CRC64,
+        HASH_CRC8,
+        HASH_CRC16,
 };
 
 #define HASH_FMT32 "%02x%02x%02x%02x"