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hash: fallback to software CRC32 implementation

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Initially, SSE4.2 support is detected via the constructor function.

Added rte_hash_crc_set_alg() function to detect and set CRC32
implementation if necessary. SSE4.2 is allowed by default.

rte_hash_crc_*byte() functions reworked so they choose available
CRC32 implementation in the runtime.

Signed-off-by: Yerden Zhumabekov <e_zhumabekov@sts.kz>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
This commit is contained in:
Yerden Zhumabekov 2015-01-29 14:50:03 +06:00 committed by Thomas Monjalon
parent d2b989045f
commit 8bae1da2af
1 changed files with 59 additions and 2 deletions
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61
lib/librte_hash/rte_hash_crc.h
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@ -45,6 +45,8 @@ extern "C" {
#endif
#include <stdint.h>
#include <rte_cpuflags.h>
#include <rte_branch_prediction.h>
/* Lookup tables for software implementation of CRC32C */
static const uint32_t crc32c_tables[8][256] = {{
@ -396,8 +398,52 @@ crc32c_sse42_u64_mimic(uint64_t data, uint64_t init_val)
return init_val;
}
#define CRC32_SW (1U << 0)
#define CRC32_SSE42 (1U << 1)
#define CRC32_x64 (1U << 2)
#define CRC32_SSE42_x64 (CRC32_x64|CRC32_SSE42)
static uint8_t crc32_alg = CRC32_SW;
/**
* Allow or disallow use of SSE4.2 instrinsics for CRC32 hash
* calculation.
*
* @param alg
* An OR of following flags:
* - (CRC32_SW) Don't use SSE4.2 intrinsics
* - (CRC32_SSE42) Use SSE4.2 intrinsics if available
* - (CRC32_SSE42_x64) Use 64-bit SSE4.2 intrinsic if available (default)
*
*/
static inline void
rte_hash_crc_set_alg(uint8_t alg)
{
switch (alg) {
case CRC32_SSE42_x64:
if (! rte_cpu_get_flag_enabled(RTE_CPUFLAG_EM64T))
alg = CRC32_SSE42;
case CRC32_SSE42:
if (! rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_2))
alg = CRC32_SW;
case CRC32_SW:
crc32_alg = alg;
default:
break;
}
}
/* Setting the best available algorithm */
static inline void __attribute__((constructor))
rte_hash_crc_init_alg(void)
{
rte_hash_crc_set_alg(CRC32_SSE42_x64);
}
/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
* Fall back to software crc32 implementation in case SSE4.2 is
* not supported
*
* @param data
* Data to perform hash on.
@ -409,11 +455,16 @@ crc32c_sse42_u64_mimic(uint64_t data, uint64_t init_val)
static inline uint32_t
rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
{
return crc32c_sse42_u32(data, init_val);
if (likely(crc32_alg & CRC32_SSE42))
return crc32c_sse42_u32(data, init_val);
return crc32c_1word(data, init_val);
}
/**
* Use single crc32 instruction to perform a hash on a 8 byte value.
* Fall back to software crc32 implementation in case SSE4.2 is
* not supported
*
* @param data
* Data to perform hash on.
@ -425,7 +476,13 @@ rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
static inline uint32_t
rte_hash_crc_8byte(uint64_t data, uint32_t init_val)
{
return crc32c_sse42_u64(data, init_val);
if (likely(crc32_alg == CRC32_SSE42_x64))
return crc32c_sse42_u64(data, init_val);
if (likely(crc32_alg & CRC32_SSE42))
return crc32c_sse42_u64_mimic(data, init_val);
return crc32c_2words(data, init_val);
}
/**