Subject: Re: Floating point .....
To: Neil A. Carson <neil@causality.com>
From: Richard Earnshaw <rearnsha@arm.com>
List: port-arm32
Date: 10/28/1998 09:00:11
> Yeah,
>
> I don't think IEEE dictates the order. ARM ended up with little endian
> byte order and big endian double word order (relative to others). I
> don't know what the history behind this is.
>
It's best to consider it as the bit order of two words, the bit-order
within the words is the same as Intel, but the word order is the same as
Motorola. If you run an ARM in big-endian mode, then the word order stays
the same, but the bit order is effectively reversed (ie, it becomes
identical to the Motorala format).
As for the reasons, when I asked one of the designers, I was told the
implementation was more efficient when you needed to write an emulator.
You can get full details in the fpa-11 data sheet (available from our web
page).
Richard.