ceph/src/include/crc32c.h

   1 #ifndef CEPH_CRC32C_H
   2 #define CEPH_CRC32C_H
   3
   4 #include <stdint.h>
   5
   6 #ifdef __cplusplus
   7 extern "C" {
   8 #endif
   9
  10 typedef uint32_t (*ceph_crc32c_func_t)(uint32_t crc, unsigned char const *data, unsigned length);
  11
  12 /*
  13  * this is a static global with the chosen crc32c implementation for
  14  * the given architecture.
  15  */
  16 extern ceph_crc32c_func_t ceph_crc32c_func;
  17
  18 extern ceph_crc32c_func_t ceph_choose_crc32(void);
  19
  20 /**
  21  * calculate crc32c for data that is entirely 0 (ZERO)
  22  *
  23  * Note: works the same as ceph_crc32c_func for data == nullptr,
  24  * but faster than the optimized assembly on certain architectures.
  25  * This is faster than intel optimized assembly, but not as fast as
  26  * ppc64le optimized assembly.
  27  *
  28  * @param crc initial value
  29  * @param length length of buffer
  30  */
  31 uint32_t ceph_crc32c_zeros(uint32_t crc, unsigned length);
  32
  33 /**
  34  * calculate crc32c
  35  *
  36  * Note: if the data pointer is NULL, we calculate a crc value as if
  37  * it were zero-filled.
  38  *
  39  * @param crc initial value
  40  * @param data pointer to data buffer
  41  * @param length length of buffer
  42  */
  43 static inline uint32_t ceph_crc32c(uint32_t crc, unsigned char const *data, unsigned length)
  44 {
  45 #ifndef HAVE_POWER8
  46   if (!data && length > 16)
  47     return ceph_crc32c_zeros(crc, length);
  48 #endif /* HAVE_POWER8 */
  49
  50   return ceph_crc32c_func(crc, data, length);
  51 }
  52
  53 #ifdef __cplusplus
  54 }
  55 #endif
  56
  57 #endif