initial code repo

[stor4nfv.git] / src / ceph / src / include / crc32c.h

diff --git a/src/ceph/src/include/crc32c.h b/src/ceph/src/include/crc32c.h
new file mode 100644 (file)
index 0000000..dd4ede6
--- /dev/null
+++ b/src/ceph/src/include/crc32c.h
@@ -0,0 +1,57 @@
+#ifndef CEPH_CRC32C_H
+#define CEPH_CRC32C_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef uint32_t (*ceph_crc32c_func_t)(uint32_t crc, unsigned char const *data, unsigned length);
+
+/*
+ * this is a static global with the chosen crc32c implementation for
+ * the given architecture.
+ */
+extern ceph_crc32c_func_t ceph_crc32c_func;
+
+extern ceph_crc32c_func_t ceph_choose_crc32(void);
+
+/**
+ * calculate crc32c for data that is entirely 0 (ZERO)
+ *
+ * Note: works the same as ceph_crc32c_func for data == nullptr, 
+ * but faster than the optimized assembly on certain architectures.
+ * This is faster than intel optimized assembly, but not as fast as 
+ * ppc64le optimized assembly.  
+ *
+ * @param crc initial value
+ * @param length length of buffer
+ */
+uint32_t ceph_crc32c_zeros(uint32_t crc, unsigned length);
+
+/**
+ * calculate crc32c
+ *
+ * Note: if the data pointer is NULL, we calculate a crc value as if
+ * it were zero-filled.
+ *
+ * @param crc initial value
+ * @param data pointer to data buffer
+ * @param length length of buffer
+ */
+static inline uint32_t ceph_crc32c(uint32_t crc, unsigned char const *data, unsigned length)
+{
+#ifndef HAVE_POWER8
+  if (!data && length > 16)
+    return ceph_crc32c_zeros(crc, length);
+#endif /* HAVE_POWER8 */
+
+  return ceph_crc32c_func(crc, data, length);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif