libftdi Archives

Subject: Re: [EEPROM branch] Dynamic string offset calculation

From: Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Fri, 24 Sep 2010 11:25:07 +0200
On Friday, 24. September 2010 10:43:36 Thomas Jarosch wrote:
> For a FT245BM type chip, the eeprom->size will be 0x80.
> This results in
> i = 0x94;
> k = 127;
> "i++ & k" will result in 0x14. The length of the manufacturer string
> is stored in 0x0f, so this is wrong for the BM type chips. Luckily
> it will be overwritten later on.
> Can you enlighten me why the offset for the "length of the manufacturer
> string descriptor" is calculated dynamically? Atleast for the FT245BM and
> the FT2232C, it's always at 0x0F. Cut'n'paste typo?

Forget about it, it's the actual string length.

I still have trouble reading the code because of the "k" bitmask wraparound 
magic. Maybe we find a better name for it, like "eeprom_size_limit"?


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