Re: [Minios-devel] [PATCH v3 20/43] mini-os: implement the memmove/memchr

[Julien Grall <julien.grall@xxxxxxx>]

On 04/16/2018 07:32 AM, Huang Shijie wrote:
> This patch is split from the Chen Baozi's old patch:
>
> "This activates the ARM code added in the previous patches. On
>   ARM, Mini-OS will boot and display some output on the console. Tested with:"
>
> Note: The code is copied from FreeBSD code:
>        freebsd/contrib/ldns/compat/memmove.c
That's only for memmove. How about memchr?

Also, can you explain in the commit message why you need them?

Cheers,

> Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
> ---
>   Makefile      |  1 +
>   lib/memmove.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   lib/string.c  | 12 ++++++++++
>   3 files changed, 87 insertions(+)
>   create mode 100644 lib/memmove.c
>
> diff --git a/Makefile b/Makefile
> index 6a05de6..3ad2522 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -62,6 +62,7 @@ src-y += lib/math.c
>   src-y += lib/printf.c
>   src-y += lib/stack_chk_fail.c
>   src-y += lib/string.c
> +src-y += lib/memmove.c
>   src-y += lib/sys.c
>   src-y += lib/xmalloc.c
>   src-$(CONFIG_XENBUS) += lib/xs.c
> diff --git a/lib/memmove.c b/lib/memmove.c
> new file mode 100644
> index 0000000..d5ac036
> --- /dev/null
> +++ b/lib/memmove.c
> @@ -0,0 +1,74 @@
> +/*
> + *     memmove.c: memmove compat implementation.
> + *
> + *     Copyright (c) 2001-2008, NLnet Labs. All rights reserved.
> + *
> + * See COPYING for the license.
> +*/
> +
> +/*
> +Copyright (c) 2005,2006, NLnetLabs
> +All rights reserved.
> +
> +Redistribution and use in source and binary forms, with or without
> +modification, are permitted provided that the following conditions are met:
> +
> +    * Redistributions of source code must retain the above copyright notice,
> +      this list of conditions and the following disclaimer.
> +    * Redistributions in binary form must reproduce the above copyright
> +      notice, this list of conditions and the following disclaimer in the
> +      documentation and/or other materials provided with the distribution.
> +    * Neither the name of NLnetLabs nor the names of its
> +      contributors may be used to endorse or promote products derived from this
> +      software without specific prior written permission.
> +
> +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
> +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
> +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> +POSSIBILITY OF SUCH DAMAGE.
> +*/
> +
> +#include <os.h>
> +#include <mini-os/lib.h>
> +
> +#ifndef HAVE_LIBC
> +
> +void *memmove(void *dest, const void *src, size_t n)
> +{
> +       uint8_t* from = (uint8_t*) src;
> +       uint8_t* to = (uint8_t*) dest;
> +
> +       if (from == to || n == 0)
> +               return dest;
> +       if (to > from && to-from < (int)n) {
> +               /* to overlaps with from */
> +               /*  <from......>         */
> +               /*         <to........>  */
> +               /* copy in reverse, to avoid overwriting from */
> +               int i;
> +               for(i=n-1; i>=0; i--)
> +                       to[i] = from[i];
> +               return dest;
> +       }
> +       if (from > to  && from-to < (int)n) {
> +               /* to overlaps with from */
> +               /*        <from......>   */
> +               /*  <to........>         */
> +               /* copy forwards, to avoid overwriting from */
> +               size_t i;
> +               for(i=0; i<n; i++)
> +                       to[i] = from[i];
> +               return dest;
> +       }
> +       memcpy(dest, src, n);
> +       return dest;
> +}
> +
> +#endif
> diff --git a/lib/string.c b/lib/string.c
> index 8b24146..c96ca41 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -225,4 +225,16 @@ int ffs(int i)
>      return 0;
>   }
>   
> +void *memchr(const void *s, int c, size_t n)
> +{
> +    if (n != 0) {
> +        const unsigned char *p = s;
> +
> +        do {
> +            if (*p++ == (unsigned char)c)
> +                return ((void *)(uintptr_t)(p - 1));
> +        } while (--n != 0);
> +    }
> +    return (NULL);
> +}
>   #endif
--
Julien Grall

_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/minios-devel