[libre-riscv-dev] [Bug 267] The efficiency of adder/subtractor

[whygee at f-cpu.org]

Have a look :
http://www.ecs.umass.edu/ece/koren/arith/simulator/Add/lookahead/

On 2020-04-07 16:44, bugzilla-daemon at libre-riscv.org wrote:
> http://bugs.libre-riscv.org/show_bug.cgi?id=267
> 
> --- Comment #9 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
> (In reply to Jock Tanner from comment #6)
>> The idea is so simple yet so out-of-the-box! I feel like I'm in a 
>> Western
>> movie, while my partner is devising a get-rich-fast scheme:
>> 
>> − And where's the catch?
>> − There is no catch.
> 
> a lot of what we're doing is like that.  the 6600 scoreboards are 
> *very*
> badly misunderstood and drastically underestimated right across the
> entire industry (thanks largely to Patterson's book on RISC 
> architectures).
> 
> consequently what's in Thornton's book "Design of a Computer" (google 
> it)
> has had to be "reinvented" and often comes attached with unnecessary 
> baggage
> such as "register renamers".
> 
> then again there are areas where we are "functional" but need serious
> improvement.  we need a Dadda multiplier algorithm for example, because
> we currently have a Wallace Tree one.
> https://bugs.libre-soc.org/show_bug.cgi?id=136