[U-Boot] [PATCH v2 5/5] tools: Add tool to add crc8 to a mac address

[Joe Hershberger]

On Mon, Dec 14, 2015 at 6:41 AM, Olliver Schinagl
<o.schinagl at ultimaker.com> wrote:
> This patch adds a little tool that takes a generic MAC address and
> generates a CRC byte for it. The output is the full MAC address without
> any separators, ready written into an EEPROM.
>
> Signed-off-by: Olliver Schinagl <o.schinagl at ultimaker.com>
> ---
>  tools/Makefile       |  4 ++++
>  tools/gen_mac_addr.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 55 insertions(+)
>  create mode 100644 tools/gen_mac_addr.c
>
> diff --git a/tools/Makefile b/tools/Makefile
> index 4a50744..6191c26 100644
> --- a/tools/Makefile
> +++ b/tools/Makefile
> @@ -43,6 +43,10 @@ envcrc-objs := envcrc.o lib/crc32.o common/env_embedded.o lib/sha1.o
>  hostprogs-$(CONFIG_CMD_NET) += gen_eth_addr
>  HOSTCFLAGS_gen_eth_addr.o := -pedantic
>
> +hostprogs-$(CONFIG_CMD_NET) += gen_mac_addr
> +gen_mac_addr-objs := gen_mac_addr.o lib/crc8.o
> +HOSTCFLAGS_gen_mac_addr.o := -pedantic
> +
>  hostprogs-$(CONFIG_CMD_LOADS) += img2srec
>  HOSTCFLAGS_img2srec.o := -pedantic
>
> diff --git a/tools/gen_mac_addr.c b/tools/gen_mac_addr.c
> new file mode 100644
> index 0000000..bd8688f
> --- /dev/null
> +++ b/tools/gen_mac_addr.c

This is not "generating a mac address", right? Its point is to create
a CRC for the user-supplied MAC address.

Perhaps a better name would be "gen_ethaddr_rom_crc".

> @@ -0,0 +1,51 @@
> +/*
> + * (C) Copyright 2016
> + * Olliver Schinagl <o.schinagl at ultimaker.com>
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <ctype.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <u-boot/crc.h>
> +
> +
> +int main(int argc, char *argv[])
> +{
> +       uint_fast8_t i;
> +       uint8_t mac_addr[7] = { 0x00 };
> +
> +       if (argc < 2) {
> +               puts("Please supply a MAC address.");
> +               return -1;
> +       }
> +
> +       if (!((strlen(argv[1]) == 12) || (strlen(argv[1]) == 17))) {
> +               puts("Please supply a valid MAC address with optionaly\n"
> +                    "dashes (-) or colons (:) as seperators.");
> +               return -1;
> +       }

You could use the eth_validate_ethaddr_str() function here instead of this code.

> +
> +       i = 0;
> +       while (*argv[1] != '\0') {
> +               char nibble[2] = { 0x00, '\n' }; /* for strtol */
> +
> +               nibble[0] = *argv[1]++;
> +               if (isxdigit(nibble[0])) {
> +                       if (isupper(nibble[0]))
> +                               nibble[0] = tolower(nibble[0]);
> +                       mac_addr[i >> 1] |= strtol(nibble, NULL, 16) << ((i % 2) ? 0 : 4) & ((i % 2) ? 0x0f : 0xf0);
> +                       i++;
> +               }
> +       }

Instead of all this you could just compile in (maybe it already is?)
the eth_parse_enetaddr() function that U-Boot uses for this very
purpose.

> +       mac_addr[6] = crc8(mac_addr, 6);
> +
> +       for (i = 0; i < 7; i++)
> +               printf("%.2x", mac_addr[i]);
> +       putchar('\n');
> +
> +       return 0;
> +}
> --
> 2.6.2
>
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