m68k/fpsp040/round.S

24 |	d1(high word) contains rounding precision:
28 |	d1(low word) contains rounding mode:
55 	swap	%d1			|set up d1.w for round prec.
64 	movel	(%a1,%d1.w*4),%a1
67 | Jump table indexed by rounding mode in d1.w.  All following assumes
81 	swap	%d1			|set up d1 for round prec.
99 	movel	(%a1,%d1.w*4),%a1
106 	swap	%d1			|set up d1 for round prec.
116 	swap	%d1			|set up d1 for round prec.
120 	movel	(%a1,%d1.w*4),%a1
126 | Input:	d1 =		PREC:ROUND
134 | Notes: the ext_grs uses the round PREC, and therefore has to swap d1
135 |	 prior to usage, and needs to restore d1 to original.
138 	swap	%d1			|have d1.w point to round precision
139 	cmpiw	#0,%d1
145 	cmpiw	#1,%d1
175 	swap	%d1			|restore d1 to original
262 	movel	(%a1,%d1.w*4),%a1
276 | bit of the mantissa (msb in d1).
279 | bit of the mantissa (msb in d1) unless this would mean the exponent
281 | exponent (d0) is set to 0 and the mantissa (d1 & d2) is not
327 	lsll	%d0,%d1		|shift ms mant by count
332 	orl	%d6,%d1		|shift the ls mant bits into the ms mant
336 	movel	%d1,LOCAL_HI(%a0)
366 	movel	LOCAL_LO(%a0),%d1 |d1 has ls mant
369 	movel	%d1,%d6		|copy ls mant into d6
374 	lsrl	%d6,%d1		|shift off all bits but those that will
376 	orl	%d1,%d0		|shift the ls mant bits into the ms mant
387 	movel	LOCAL_LO(%a0),%d1	|d1 has ls mant
389 	bfffo	%d1{#0:#32},%d7	|find first 1 in ls mant to d7)
391 	lsll	%d7,%d1		|shift first 1 to integer bit in ms mant
393 	movel	%d1,LOCAL_HI(%a0)	|store exp
428 	clrl	%d1		|load d1 with ext threshold
431 	tstb	%d1		|check for inex
440 	movew	#dbl_thresh,%d1	|put copy of threshold in d1
441 	movel	%d1,%d0		|copy d1 into d0
448 	tstb	%d1		|check flag
453 	movew	#sgl_thresh,%d1	|put copy of threshold in d1
454 	movel	%d1,%d0		|copy d1 into d0
461 	tstb	%d1		|check flag
475 	movew	%d1,LOCAL_EX(%a0)		|load exp with threshold
476 	movel	#0,LOCAL_HI(%a0)	|set d1 = 0 (ms mantissa)
490 |	d1{15:0}	denormalization threshold
494 |	d1.b		inexact flag:  all ones means inexact result
514 	movel	%d1,%d0			|copy the denorm threshold
515 	subw	LOCAL_EX(%a0),%d1		|d1 = threshold - uns exponent
516 	bles	no_lp			|d1 <= 0
517 	cmpw	#32,%d1
518 	blts	case_1			|0 = d1 < 32
519 	cmpw	#64,%d1
520 	blts	case_2			|32 <= d1 < 64
521 	bra	case_3			|d1 >= 64
526 	clrb	%d1			|set no inex2 reported
530 | case (0<d1<32)
536 	subw	%d1,%d0			|d0 = 32 - d1
538 	bfextu	%d2{%d1:%d0},%d2		|d2 = new LOCAL_HI
539 	bfextu	LOCAL_HI(%a0){%d0:#32},%d1	|d1 = new LOCAL_LO
542 	movel	%d1,LOCAL_LO(%a0)		|store new LOCAL_LO
543 	clrb	%d1
547 	st	%d1
559 | case (32<=d1<64)
564 	subw	#32,%d1			|d1 now between 0 and 32
566 	subw	%d1,%d0			|d0 = 32 - d1
568 	bfextu	%d2{%d1:%d0},%d2		|d2 = new LOCAL_LO
569 	bfextu	LOCAL_HI(%a0){%d0:#32},%d1	|d1 = new G,R,S
570 	bftst	%d1{#2:#30}
574 	movel	%d1,%d0
575 	clrb	%d1
578 	movel	%d1,%d0
580 	st	%d1
594 | d1 >= 64 Force the exponent to be the denorm threshold with the
604 	cmpw	#64,%d1
606 	cmpw	#65,%d1
609 | Shift value is out of range.  Set d1 for inex2 flag and
615 	st	%d1
620 	bfextu	%d0{#2:#30},%d1
626 	bfextu	%d0{#1:#31},%d1
631 	tstl	%d1
637 	clrb	%d1
642 	st	%d1