[U-Boot] [PATCH 3/3] dfu: Introduction of the "dfu_checksum_method" env variable for checksum method setting

[Lukasz Majewski]

Hi Marek,

> On Monday, March 31, 2014 at 10:48:49 AM, Lukasz Majewski wrote:
> > Up till now the CRC32 of received data was calculated
> > unconditionally. The standard crc32 implementation causes long
> > delays when large images were uploaded.
> 
> You might want to check common/cmd_hash.c and include/hash.h for the 
> hash_command() call. It does the resolution of the hash algorithm
> from it's name and you can operate also SHA1 and SHA256 with it. It
> would be nice if you could just extend it a bit and use that instead
> of adding another ad-hoc mechanism.
> 
> Do you think it'd be possible to reuse it please ?

I think, that crc32 shall be calculated when needed. That is why I've
added a dfu_ckecksum_method variable. 

With its help it is now possible to use different algorithms for
checking - not only crc32 (which in u-boot is the default and painfully
slow implementation).

In the future the code:
if (dfu_checksum_method == DFU_CRC32)
	crc32 calculation;

will be changed to:

switch (dfu_checksum_method) {
	case CRC32:
		crc32 calculation;
		break;
	case SHA1:
		sha1 calculation;
		break;
	case MD5:
		md5 calculation;
		break;
}

Moreover it is possible to dynamically change the checksum method
(between invoking dfu command) via adjusting "dfu_checksum_method"
variable.

The default approach is to not calculate anything.

> 
> Best regards,
> Marek Vasut


-- 
Best regards,

Lukasz Majewski

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