From: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Sent: 19 September 2023 16:15 > > On Tue, Sep 19, 2023 at 02:35:25PM +0000, David Laight wrote: > > From: Matthew Wilcox <willy@xxxxxxxxxxxxx> > > > Sent: 19 September 2023 15:26 > > > > > > On Tue, Sep 19, 2023 at 01:23:08PM +0000, David Laight wrote: > > > > > Well, that sucks. What do you suggest for Coldfire? > > > > > > > > Can you just do a 32bit xor ? > > > > Unless you've got smp m68k I'd presume it is ok? > > > > (And assuming you aren't falling off a page.) > > > > > > Patch welcome. ... > I have a 68020 book; what I don't have is a Coldfire manual. > > Anyway, that's not the brief. We're looking to (eg) clear bit 0 > and test whether bit 7 was set. So it's the sign bit of the byte, > not the sign bit of the int. Use the address of the byte as an int and xor with 1u<<24. The xor will do a rmw on the three bytes following, but I doubt that matters. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
