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The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:15:19
Marcus Watts (mdw@umich.edu)
Mon, 05 Oct 98 18:54:53 -0400
Dan McDonald <danmcd@Eng.Sun.COM> writes:
> SPARC has no rotate instruction, and neither does MIPS or PowerPC. Instead,
Um, actually, not quite. PowerPC has rotate instructions. Other machines
that have rotates appear to include the h8-300 (whatever that is), i960,
m88k, and pyramid. To be fair, it does seem to be a popular fad to
leave out rotates (and indeed neither sparc nor mips have them.)
Some compilers actually know how to generate rotate instructions.
Gnu cc 2.6.2 for i386 will produce a rotate instruction for this
code:
subr(j)
unsigned long j;
{
return (j<<5 | (j >> (32-5)));
}
(It's not very smart about this. Changing | to + breaks this.
Also, it doesn't know how to generate a rotate by a variable
amount, which is a shame because this really helps rc6.)
Using inline asm code to produce a rotate may actually be a bad
thing on these machines.
-Marcus Watts
UM ITD PD&D Umich Systems Group
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:15:19