rte_cksum.h

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/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.
 * Copyright(c) 2010-2014 Intel Corporation.
 * Copyright(c) 2014 6WIND S.A.
 * All rights reserved.
 */

#ifndef _RTE_CKSUM_H_
#define _RTE_CKSUM_H_

#include <stdint.h>

#include <rte_byteorder.h>
#include <rte_common.h>
#include <rte_mbuf.h>

#ifdef __cplusplus
extern "C" {
#endif


static inline uint32_t
__rte_raw_cksum(const void *buf, size_t len, uint32_t sum)
{
    const void *end;

    for (end = RTE_PTR_ADD(buf, RTE_ALIGN_FLOOR(len, sizeof(uint16_t)));
         buf != end; buf = RTE_PTR_ADD(buf, sizeof(uint16_t))) {
        uint16_t v;

        memcpy(&v, buf, sizeof(uint16_t));
        sum += v;
    }

    /* if length is odd, keeping it byte order independent */
    if (unlikely(len % 2)) {
        uint16_t left = 0;

        memcpy(&left, end, 1);
        sum += left;
    }

    return sum;
}

static inline uint16_t
__rte_raw_cksum_reduce(uint32_t sum)
{
    sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
    sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
    return (uint16_t)sum;
}

static inline uint16_t
rte_raw_cksum(const void *buf, size_t len)
{
    uint32_t sum;

    sum = __rte_raw_cksum(buf, len, 0);
    return __rte_raw_cksum_reduce(sum);
}

static inline int
rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len,
    uint16_t *cksum)
{
    const struct rte_mbuf *seg;
    const char *buf;
    uint32_t sum, tmp;
    uint32_t seglen, done;

    /* easy case: all data in the first segment */
    if (off + len <= rte_pktmbuf_data_len(m)) {
        *cksum = rte_raw_cksum(rte_pktmbuf_mtod_offset(m,
                const char *, off), len);
        return 0;
    }

    if (unlikely(off + len > rte_pktmbuf_pkt_len(m)))
        return -1; /* invalid params, return a dummy value */

    /* else browse the segment to find offset */
    seglen = 0;
    for (seg = m; seg != NULL; seg = seg->next) {
        seglen = rte_pktmbuf_data_len(seg);
        if (off < seglen)
            break;
        off -= seglen;
    }
    RTE_ASSERT(seg != NULL);
    if (seg == NULL)
        return -1;
    seglen -= off;
    buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
    if (seglen >= len) {
        /* all in one segment */
        *cksum = rte_raw_cksum(buf, len);
        return 0;
    }

    /* hard case: process checksum of several segments */
    sum = 0;
    done = 0;
    for (;;) {
        tmp = __rte_raw_cksum(buf, seglen, 0);
        if (done & 1)
            tmp = rte_bswap16((uint16_t)tmp);
        sum += tmp;
        done += seglen;
        if (done == len)
            break;
        seg = seg->next;
        buf = rte_pktmbuf_mtod(seg, const char *);
        seglen = rte_pktmbuf_data_len(seg);
        if (seglen > len - done)
            seglen = len - done;
    }

    *cksum = __rte_raw_cksum_reduce(sum);
    return 0;
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_CKSUM_H_ */