[PATCH v2 09/10] net: lib: add ether_addr_inc() helper

[Sascha Hauer]

On Mon, Oct 02, 2023 at 12:16:53PM +0200, Oleksij Rempel wrote:
> Add helper function to calculate Ethernet address by incriminating it.
> This helper can be used for multiport devices like switches to generate
> address for each port based on one stored address.
> 
> Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
> ---
>  include/net.h |  1 +
>  net/lib.c     | 25 +++++++++++++++++++++++++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/include/net.h b/include/net.h
> index a0ef8bee04..fe82451cc9 100644
> --- a/include/net.h
> +++ b/include/net.h
> @@ -360,6 +360,7 @@ int setenv_ip(const char *name, IPaddr_t ip);
>  
>  int string_to_ethaddr(const char *str, u8 enetaddr[6]);
>  void ethaddr_to_string(const u8 enetaddr[6], char *str);
> +void ether_addr_inc(u8 *dst_addr, const u8 *src_addr, u32 increment);
>  
>  #ifdef CONFIG_NET_RESOLV
>  int resolv(const char *host, IPaddr_t *ip);
> diff --git a/net/lib.c b/net/lib.c
> index d4536441bd..dc7d83bc6d 100644
> --- a/net/lib.c
> +++ b/net/lib.c
> @@ -44,6 +44,31 @@ void ethaddr_to_string(const u8 enetaddr[ETH_ALEN], char *str)
>  		 enetaddr[4], enetaddr[5]);
>  }
>  
> +/**
> + * ether_addr_inc - Increment an Ethernet address.
> + * @dst_addr: Destination address to store the incremented address.
> + * @src_addr: Source address to be incremented.
> + * @increment: Value by which to increment the source address.
> + *
> + * This function increments the given source Ethernet address by
> + * the specified increment value, storing the result in the
> + * destination address.
> + */
> +void ether_addr_inc(u8 *dst_addr, const u8 *src_addr, u32 increment)
> +{
> +	u32 value;
> +	int i;
> +
> +	for(i = 0; i < 6; ++i)
> +		dst_addr[i] = src_addr[i];
> +
> +	for(i = 5; i >= 0 && increment; --i) {
> +		value = dst_addr[i] + increment;
> +		dst_addr[i] = value & 0xFF;
> +		increment = value >> 8;
> +	}
> +}

The Kernel already has eth_addr_add() and more helpers. How about
adopting these instead?

Sascha

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