Re: Help decoding a vax instruction

[coypu%sdf.org@localhost]

On Wed, Aug 21, 2019 at 03:59:16PM +0000, coypu%sdf.org@localhost wrote:
> On Wed, Aug 21, 2019 at 01:21:17PM +0200, Anders Magnusson wrote:
> > Den 2019-08-21 kl. 12:11, skrev coypu%sdf.org@localhost:
> > > hi folks,
> > > 
> > > I'm a vax newbie. What does this one do?
> > > 
> > >     c:	98 40 a0 02 	cvtbl 0x2(r0)[r0],15 <e+0x15>
> > > 
> > Heh!
> > 
> > cvtbl = sign-extend byte into long
> > 
> > 2(r0)[r0] = 2+r0+sizeof(byte)*r0.  Indexing, similar exists on x86. Uses
> > source size (b) for indexing size.
> > 
> > 15 = address 15 in memory.
> > 
> > -- R
> 
> Seems to be an addressing mode that GCC/vax struggles with. Using the
> following code (-O2 -c)

Urrrggh, "if built on debian 9.9" (but not netbsd)
I'm going to go look at other issues now...