9 Nov
2017
9 Nov
'17
1:14 p.m.
On 9 Nov 2017, at 07:37, Lars Brinkhoff
<lars(a)nocrew.org> wrote:
Bakul Shah wrote:
1 bit bytes, the smallest addressable unit on the PDP-10, sounds kinda cool actually. Now
would those be signed or unsigned?
The PowerPC was great at smashing and swizzling bit fields and emulating other CPU
instruction sets with different memory layouts, because it could rotate and mask very
quickly! You could do byte reversal in three instructions: "rotate left" 8 to
position two of the bytes, then two “rotate left word immediate then mask insert”
instructions.
https://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.alang…
<https://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.alangref/idalangref_32bit_rtate_shift.htm>
http://sametwice.com/rlwinm <http://sametwice.com/rlwinm>
https://www.google.com/patents/US20140208067
<https://www.google.com/patents/US20140208067>
PowerPC AltiVec was a really beautiful instruction set.
https://en.wikipedia.org/wiki/AltiVec <https://en.wikipedia.org/wiki/AltiVec>
-Don
I agree that `char' shouldn't do double
duty as the smallest
addressable unit and I was suggesing uint8_t does that job.
There are still machines around where 8-bit bytes isn't a natural fit.