util: Add CRC16 (CCITT) calculation routines

Import CRC16 calculation routines from Linux kernel v5.10:

  include/linux/crc-ccitt.h
  lib/crc-ccitt.c

to QEMU:

  include/qemu/crc-ccitt.h
  util/crc-ccitt.c

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20210123104016.17485-7-bmeng.cn@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
[PMD: Restrict compilation to system emulation]
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/include/qemu/crc-ccitt.h b/include/qemu/crc-ccitt.h
new file mode 100644
index 0000000000..06ee55b159
--- /dev/null
+++ b/include/qemu/crc-ccitt.h
@@ -0,0 +1,33 @@
+/*
+ * CRC16 (CCITT) Checksum Algorithm
+ *
+ * Copyright (c) 2021 Wind River Systems, Inc.
+ *
+ * Author:
+ *   Bin Meng <bin.meng@windriver.com>
+ *
+ * From Linux kernel v5.10 include/linux/crc-ccitt.h
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#ifndef _CRC_CCITT_H
+#define _CRC_CCITT_H
+
+extern uint16_t const crc_ccitt_table[256];
+extern uint16_t const crc_ccitt_false_table[256];
+
+extern uint16_t crc_ccitt(uint16_t crc, const uint8_t *buffer, size_t len);
+extern uint16_t crc_ccitt_false(uint16_t crc, const uint8_t *buffer, size_t len);
+
+static inline uint16_t crc_ccitt_byte(uint16_t crc, const uint8_t c)
+{
+    return (crc >> 8) ^ crc_ccitt_table[(crc ^ c) & 0xff];
+}
+
+static inline uint16_t crc_ccitt_false_byte(uint16_t crc, const uint8_t c)
+{
+    return (crc << 8) ^ crc_ccitt_false_table[(crc >> 8) ^ c];
+}
+
+#endif /* _CRC_CCITT_H */