3 ms·
What puzzled me here was that it took so many years for someone to optimize this. I looked at the code and dug around for 'barrel shifters'. Funnily enough, th
by ableal 17y ago
What puzzled me here was that it took so many years for someone to optimize this. I looked at the code and dug around for 'barrel shifters'.
Funnily enough, this page http://answers.google.com/answers/threadview?id=388350 http://answers.google.com/answers/threadview?id=388350 says that in 1986 both the i386 and 68030 came with one, but it was missing from the Pentium 4.
- DarkShikari 17y agoI doubt the Pentium 4 had no barrel shifter, as its shift instructions have single-cycle latency. It does seem, however, that the Prescott can do rotate instructions in one cycle while the Northwood took 4 (thanks, Mubench!).