signed nibble

[H. S. Teoh]

On Mon, Jan 07, 2019 at 08:41:32PM +0000, Patrick Schluter via Digitalmars-d-learn wrote:
> On Monday, 7 January 2019 at 20:28:21 UTC, H. S. Teoh wrote:
> > On Mon, Jan 07, 2019 at 08:06:17PM +0000, Patrick Schluter via
> > Digitalmars-d-learn wrote:
[...]
> > > Up to 32 bit processors, shifting was more expensive than
> > > branching.
> > 
> > Really?  Haha, never knew that, even though I date all the way back
> > to writing assembly on 8-bit processors. :-D
> > 
> Most of my career was programming for 80186. Shifting by one was 2
> cycles in register and 15 in memory. Shifting by 4, 9 cycles for
> regs/21 for mem. And 80186 was a fast shifter compared to 8088/86 or
> 68000 (8+2n cycles).

I used to hack 6502 assembly code.  During the PC revolution I wrote an
entire application in 8088 assembly.  Used to know many of the opcodes
and cycle counts by heart like you do, but it's all but a faint memory
now.


T

-- 
Right now I'm having amnesia and deja vu at the same time. I think I've forgotten this before.