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Content-class: urn:content-classes:message
Subject: RE: [PATCH 5/6] net: add smaller IPv4 cksum function for simple cases
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Date: Thu, 17 Oct 2024 19:15:10 +0200
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Thread-Topic: [PATCH 5/6] net: add smaller IPv4 cksum function for simple cases
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References: <20241017142214.1669370-1-bruce.richardson@intel.com>
 <20241017142214.1669370-6-bruce.richardson@intel.com>
From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
	<dev@dpdk.org>
Cc: "Jerin Jacob" <jerinj@marvell.com>,
 "Aman Singh" <aman.deep.singh@intel.com>,
 "Konstantin Ananyev" <konstantin.v.ananyev@yandex.ru>
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> +/**
> + * Process the IPv4 checksum of an IPv4 header without any =
extensions.
> + *
> + * The checksum field does NOT have to be set by the caller, the =
field
> + * is skipped by the calculation.
> + *
> + * @param ipv4_hdr
> + *   The pointer to the contiguous IPv4 header.
> + * @return
> + *   The complemented checksum to set in the IP packet.
> + */
> +__rte_experimental
> +static inline uint16_t
> +rte_ipv4_cksum_simple(const struct rte_ipv4_hdr *ipv4_hdr)
> +{
> +	const uint16_t *v16_h;
> +	uint32_t ip_cksum;
> +
> +	/*
> +	 * Compute the sum of successive 16-bit words of the IPv4 header,
> +	 * skipping the checksum field of the header.
> +	 */
> +	v16_h =3D (const unaligned_uint16_t *)&ipv4_hdr->version_ihl;
> +	ip_cksum =3D v16_h[0] + v16_h[1] + v16_h[2] + v16_h[3] +
> +		v16_h[4] + v16_h[6] + v16_h[7] + v16_h[8] + v16_h[9];
> +
> +	/* reduce 32 bit checksum to 16 bits and complement it */
> +	ip_cksum =3D (ip_cksum & 0xffff) + (ip_cksum >> 16);
> +	ip_cksum =3D (ip_cksum & 0xffff) + (ip_cksum >> 16);
> +	ip_cksum =3D (~ip_cksum) & 0x0000FFFF;
> +	return (ip_cksum =3D=3D 0) ? 0xFFFF : (uint16_t) ip_cksum;

The zero exception does not apply to the checksum stored in the IP =
header, only to the checksum in the UDP header.

> +}

Besides that, for the series,
Acked-by: Morten Br=F8rup <mb@smartsharesystems.com>