Floating Point-The Results Are In!
Ed G.
edgee at cyberpass.net
Tue May 12 12:21:12 AEST 1998
> I don't know what the code above is intended to do, but it's not
> floating point. At the very best, it would indicate the use of the
> floating point registers for straightforward data moves. I stand by
> my assertion that tar doesn't use floating point, neither in the
> Seventh Edition nor elsewhere.
I agree: tar doesn't *use* floating point.
However, from what I can determine the floating point ops in tar are
not some weird way of moving data around, nor is floating point
being used to do long arithmetic as some have suggested.
Compare the first few tar floating point ops with a dummy program
consisting of a single call to scanf:
tar, 106 floating point ops:
0: SETD ;170011
20532: STCFD F0,(R1) ;176011
20562: STF F0,(R1) ;174011
22406: LDF F0,(R4)+ ;172424
22410: STF F0,-(SP) ;174046
22460: LDF F0,(R4)+ ;172424
22462: STF F0,-(SP) ;174046
22620: LDF F0,(R4)+ ;172424
22622: STF F0,-(SP) ;174046
24124: LDF F0,4(R5) ;172465 000004
24130: STF F0,-(SP) ;174046
26616: LDF F0,#56200 ;172427 056200
26622: STF F0,177732(R5) ;174065 177732
etc.
scanf, 106 floating point ops:
000000: SETD ;170011
002764: STCFD F0,(R1) ;176011
003014: STF F0,(R1) ;174011
004346: LDF F0,(R4)+ ;172424
004350: STF F0,-(SP) ;174046
004420: LDF F0,(R4)+ ;172424
004422: STF F0,-(SP) ;174046
004560: LDF F0,(R4)+ ;172424
004562: STF F0,-(SP) ;174046
004750: LDF F0,4(R5) ;172465 000004
004754: STF F0,-(SP) ;174046
006410: LDF F0,#56200 ;172427 056200
006414: STF F0,177732(R5) ;174065 177732
So it would appear that whatever floating point there is in tar comes
from library routines which have been linked in, but which tar does
not use.
"When you hear hoofbeats, think horses, not zebras."
Ed
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