Re: [PATCH v4 1/5] CRC64 commands documentation

[Ulf Samuelsson <binutils@emagii.com>]

Den 2023-02-21 kl. 13:53, skrev Nick Clifton:
> Hi Ulf,
>
>> diff --git a/COPYING.CRC64 b/COPYING.CRC64
>> new file mode 100755
>> index 00000000000..618e1c63dae
>> --- /dev/null
>> +++ b/COPYING.CRC64
>> @@ -0,0 +1,42 @@
>> +The GNU linker contains CRC routines that are used to implement the
>> +CRC64 command in the output section.
>> +
>> +The CRC routines are extracted from LIBCRC available at
>> +
>> +They are used to
>> +* https://www.libcrc.org/
>> +* https://github.com/lammertb/libcrc/tree/v2.0
>
> Umm, why do you have the "They are used to" line here ?


Cut and paste, sorry about that.

>
>> +/*
>> + * Library: libcrc
>> + * File:    src/crc64.c
>> + * Author:  Lammert Bies
>> + *
>> + * This file is licensed under the MIT License as stated below
>> + *
>> + * Copyright (c) 2016 Lammert Bies
>> + *
>> + * Permission is hereby granted, free of charge, to any person 
>> obtaining a copy
>> + * of this software and associated documentation files (the 
>> "Software"), to deal
>> + * in the Software without restriction, including without limitation 
>> the rights
>> + * to use, copy, modify, merge, publish, distribute, sublicense, 
>> and/or sell
>> + * copies of the Software, and to permit persons to whom the 
>> Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be 
>> included in all
>> + * copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
>> EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
>> MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 
>> SHALL THE
>> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
>> OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
>> ARISING FROM,
>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
>> DEALINGS IN THE
>> + * SOFTWARE.
>> + *
>> + * Description
>> + * -----------
>> + * The source file src/crc64.c contains the routines which are 
>> needed to
>> + * calculate a 64 bit CRC value of a sequence of bytes.
>> + */
>
> Given that the library is not being incorporated as-is into the linker 
> sources
> you should probably indicate the relocated location of the src/crc64.c 
> code.
>
That is the LICENSE, right?.

The user needs to supply his own routines which uses the table.
They can do so by extracting the routines from the libcrc.

A cool feature would be to be able to print out the CRC routine
from the linker.

>
>> diff --git a/ld/ld.texi b/ld/ld.texi
>> index 7802f0661b0..2042fadb33e 100644
>
>> +The CRC32 <polynome> command defines some global symbols.
>> +
>> +* @code{___CRC32___}       address of the CRC32 checksum
>> +
>> +* @code{___CRC32_START___} first address in the checked area.
>> +
>> +* @code{___CRC32_END___}   first address past the checked area.
>
> I probably should have mentioned this in my comments for the [v4 0/5]
> email, but are these symbol definitions really necessary ?  Given
> that the CRC functions have to be invoked from the linker script with
> symbol names in their parameters, why define extra symbols ?

I expect that the user can provide an expression.

    CRC64 ECMA   (header + 16, header + 256 + sizeof(...))

so I do not neccessary have a label to find.

Creating my own labels seemed to simplify a lot.

I think, but am not 100% sure, that you could add "illegal" names
if we want to avoid conflict with the user defined labels.

I.E: CRC-32, CRC-32-START, CRC-32-END


>
> Cheers
>   Nick
>