lkoop@pnet01.cts.com (Lamonte Koop) (12/17/90)
Does anyone have some good examples of DIRECTLY accessing the 68881 or 68882
math coprocessors from within a program? (without going through the math
libraries). Specifically, I'm looking for assembly source examples if
possible. I have a partially working code model, but would be interested to
see other examples or hear other ideas about the subject as I have hit a few
'interesting' effects.
LaMonte Koop
Internet: lkoop@pnet01.cts.com ARPA: crash!pnet01!lkoop@nosc.mil
UUCP: {hplabs!hp-sdd ucsd nosc}!crash!pnet01!lkoop
A scientist is one who finds interest in the kinetic energy of Jell-O
moving at ridiculous velocities...an engineer is one who can find a
real-life application for such silliness.jcs@crash.cts.com (John Schultz) (12/18/90)
In <6361@crash.cts.com> lkoop@pnet01.cts.com (Lamonte Koop) writes: >Does anyone have some good examples of DIRECTLY accessing the 68881 or 68882 >math coprocessors from within a program? (without going through the math >libraries). Specifically, I'm looking for assembly source examples if >possible. I have a partially working code model, but would be interested to >see other examples or hear other ideas about the subject as I have hit a few >'interesting' effects. > Using the 881/882 is just as easy as the 030. Here's a simple example that computes distance. Pick up "68030 Assembly Language Reference", by Steve Williams [Addision Wesley]. It's got C and equivalent 882 asm examples (in addition to 030 examples). ; This function works on long integers. It converts the longs to ; reals with the fmove.l instruction, sums the squares, then takes the ; sqrt, then fmove.l converts back to long. fmul could also be used ; but fsglmul is faster. section distance,code OPT p=68020/68881 ; Necessary for Adapt to use ; 020/030/881/882 xdef _distance ; extern long __asm distance64(register __d0 long x, ; register __d1 long y, ; register __d2 long z); _distance: fmove.l d0,fp0 fsglmul fp0,fp0 fmove.l d1,fp1 fsglmul fp1,fp1 fadd fp0,fp1 fmove.l d2,fp0 fsglmul fp0,fp0 fadd fp1,fp0 fsqrt fp0 fmove.l fp0,d0 rts END -------------------------------------------------------------- Here's the code and cycles: PMA 68030+ Program Module Analyzer V17 ADAPT Release 1.00 Copyright ) 1990, HoweSoft, Inc. All Rights Reserved. * Program_unit #0 name "<UNNAMED>". * Hunk_Name #0 name "distance". * Code_Hunk [PUBLIC] #0 Length = 44 bytes [11 longwords] fmove.l D0,FP0 ; 60 CYCLES fsglmul.x FP0,FP0 ; 59 CYCLES fmove.l D1,FP1 ; 60 CYCLES fsglmul.x FP1,FP1 ; 59 CYCLES fadd.x FP0,FP1 ; 51 CYCLES fmove.l D2,FP0 ; 60 CYCLES fsglmul.x FP0,FP0 ; 59 CYCLES fadd.x FP1,FP0 ; 51 CYCLES fsqrt.x FP0 ; 107 CYCLES fmove.l FP0,D0 ; 100 CYCLES rts ; 16 CYCLES DC.W 0 * 682 Total Cycles * Hunk_Ext: * Type = ext_def, Name = "_distance" * Hunk_End. Pretty fast, eh? Have fun, John