Re: ANN: SwiftX for ARM and i386

On Wed, 19 Nov 2003 21:21:39 -0000, Jeff Massung
<[EMAIL PROTECTED]> wrote:

>The GameBoy Advance (using ARM7TDMI) has a ROM that is only 16-bits 
>wide. Writing in THUMB assembly produces code that is roughly the same 
>size (perhaps a little smaller for some routines or larger for others), 
>but runs about 160% faster than the equivelant ARM code.

The Thumb instruction set really only pays off under the following
circumstances
1) The data bus is 8 or 16 bits wide
2) There is no instruction cache
3) Instruction memory space is limited.
These are in turn impacted by a requirement for absolute
minimum hardware cost. Our investigations suggest that
Thumb is most widely used in consumer products (consoles,
mobile phones etc). These are high volume products with
a low number of developer seats. In order to provide full
system services on an ARM you must support the ARM instruction
set first. Note also that the Thumb instruction set is
also focused on frame stack languages and restricts access
to the upper eight registers.

MPE has been shipping VFX Forth ARM cross compilers for
about four years now including TCP/IP stacks and our
upcoming CANopen system. In our main market, deep
embedded industrial applications, Thumb is not an
important issue.

Please note that I am not arguing against Thumb, only that
in our application domains it is less important.

Stephen
--
Stephen Pelc, [EMAIL PROTECTED]
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeltd.demon.co.uk - free VFX Forth downloads