Re: [PATCH v6 2/7] hash: add assembly implementation of CRC32 intrinsics

["Liang, Cunming" <cunming.liang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On 1/29/2015 4:48 PM, Yerden Zhumabekov wrote:
> Added:
> - crc32c_sse42_u32() emits 'crc32l' asm instruction;
> - crc32c_sse42_u64() emits 'crc32q' asm instruction;
> - crc32c_sse42_u64_mimic(), wrapper in case of run on 32-bit platform.
>
> Signed-off-by: Yerden Zhumabekov <e_zhumabekov-8EHiFRVJVgQ@public.gmane.org>
> ---
>   lib/librte_hash/rte_hash_crc.h |   34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
>
> diff --git a/lib/librte_hash/rte_hash_crc.h b/lib/librte_hash/rte_hash_crc.h
> index 4da7ca4..fe35996 100644
> --- a/lib/librte_hash/rte_hash_crc.h
> +++ b/lib/librte_hash/rte_hash_crc.h
> @@ -363,6 +363,40 @@ crc32c_2words(uint64_t data, uint32_t init_val)
>   	return crc;
>   }
>   
> +static inline uint32_t
> +crc32c_sse42_u32(uint32_t data, uint32_t init_val)
> +{
> +	__asm__ volatile(
> +			"crc32l %[data], %[init_val];"
> +			: [init_val] "+r" (init_val)
> +			: [data] "rm" (data));
> +	return init_val;
> +}
> +
> +static inline uint32_t
> +crc32c_sse42_u64(uint64_t data, uint64_t init_val)
> +{
> +	__asm__ volatile(
> +			"crc32q %[data], %[init_val];"
> +			: [init_val] "+r" (init_val)
> +			: [data] "rm" (data));
> +	return init_val;
> +}
[LCM] I'm curious about the benefit of replacing CRC32 intrinsic 
"_mm_crc32_u32/64".
> +
> +static inline uint32_t
> +crc32c_sse42_u64_mimic(uint64_t data, uint64_t init_val)
> +{
> +	union {
> +		uint32_t u32[2];
> +		uint64_t u64;
> +	} d;
> +
> +	d.u64 = data;
> +	init_val = crc32c_sse42_u32(d.u32[0], init_val);
> +	init_val = crc32c_sse42_u32(d.u32[1], init_val);
> +	return init_val;
> +}
> +
>   /**
>    * Use single crc32 instruction to perform a hash on a 4 byte value.
>    *