checksum.c

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/* MN10300 Optimised checksumming wrappers
 *
 * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/errno.h>
#include <asm/byteorder.h>
#include <asm/uaccess.h>
#include <asm/checksum.h>
#include "internal.h"

static inline unsigned short from32to16(__wsum sum)
{
    asm("   add %1,%0       \n"
        "   addc    0xffff,%0   \n"
        : "=r" (sum)
        : "r" (sum << 16), "0" (sum & 0xffff0000)
        : "cc"
        );
    return sum >> 16;
}

__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
    return ~do_csum(iph, ihl * 4);
}
EXPORT_SYMBOL(ip_fast_csum);

__wsum csum_partial(const void *buff, int len, __wsum sum)
{
    __wsum result;

    result = do_csum(buff, len);
    result += sum;
    if (sum > result)
        result++;
    return result;
}
EXPORT_SYMBOL(csum_partial);

__sum16 ip_compute_csum(const void *buff, int len)
{
    return ~from32to16(do_csum(buff, len));
}
EXPORT_SYMBOL(ip_compute_csum);

__wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
{
    copy_from_user(dst, src, len);
    return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy);

__wsum csum_partial_copy_nocheck(const void *src, void *dst,
                 int len, __wsum sum)
{
    sum = csum_partial(src, len, sum);
    memcpy(dst, src, len);
    return sum;
}
EXPORT_SYMBOL(csum_partial_copy_nocheck);

__wsum csum_partial_copy_from_user(const void *src, void *dst,
                   int len, __wsum sum,
                   int *err_ptr)
{
    int missing;

    missing = copy_from_user(dst, src, len);
    if (missing) {
        memset(dst + len - missing, 0, missing);
        *err_ptr = -EFAULT;
    }

    return csum_partial(dst, len, sum);
}
EXPORT_SYMBOL(csum_partial_copy_from_user);

__wsum csum_and_copy_to_user(const void *src, void *dst,
                 int len, __wsum sum,
                 int *err_ptr)
{
    int missing;

    missing = copy_to_user(dst, src, len);
    if (missing) {
        memset(dst + len - missing, 0, missing);
        *err_ptr = -EFAULT;
    }

    return csum_partial(src, len, sum);
}
EXPORT_SYMBOL(csum_and_copy_to_user);