xref: /openbmc/linux/arch/m68k/fpsp040/round.S (revision e00d82d0)
1|
2|	round.sa 3.4 7/29/91
3|
4|	handle rounding and normalization tasks
5|
6|
7|
8|		Copyright (C) Motorola, Inc. 1990
9|			All Rights Reserved
10|
11|       For details on the license for this file, please see the
12|       file, README, in this same directory.
13
14|ROUND	idnt    2,1 | Motorola 040 Floating Point Software Package
15
16	|section	8
17
18#include "fpsp.h"
19
20|
21|	round --- round result according to precision/mode
22|
23|	a0 points to the input operand in the internal extended format
24|	d1(high word) contains rounding precision:
25|		ext = $0000xxxx
26|		sgl = $0001xxxx
27|		dbl = $0002xxxx
28|	d1(low word) contains rounding mode:
29|		RN  = $xxxx0000
30|		RZ  = $xxxx0001
31|		RM  = $xxxx0010
32|		RP  = $xxxx0011
33|	d0{31:29} contains the g,r,s bits (extended)
34|
35|	On return the value pointed to by a0 is correctly rounded,
36|	a0 is preserved and the g-r-s bits in d0 are cleared.
37|	The result is not typed - the tag field is invalid.  The
38|	result is still in the internal extended format.
39|
40|	The INEX bit of USER_FPSR will be set if the rounded result was
41|	inexact (i.e. if any of the g-r-s bits were set).
42|
43
44	.global	round
45round:
46| If g=r=s=0 then result is exact and round is done, else set
47| the inex flag in status reg and continue.
48|
49	bsrs	ext_grs			|this subroutine looks at the
50|					:rounding precision and sets
51|					;the appropriate g-r-s bits.
52	tstl	%d0			|if grs are zero, go force
53	bne	rnd_cont		|lower bits to zero for size
54
55	swap	%d1			|set up d1.w for round prec.
56	bra	truncate
57
58rnd_cont:
59|
60| Use rounding mode as an index into a jump table for these modes.
61|
62	orl	#inx2a_mask,USER_FPSR(%a6) |set inex2/ainex
63	lea	mode_tab,%a1
64	movel	(%a1,%d1.w*4),%a1
65	jmp	(%a1)
66|
67| Jump table indexed by rounding mode in d1.w.  All following assumes
68| grs != 0.
69|
70mode_tab:
71	.long	rnd_near
72	.long	rnd_zero
73	.long	rnd_mnus
74	.long	rnd_plus
75|
76|	ROUND PLUS INFINITY
77|
78|	If sign of fp number = 0 (positive), then add 1 to l.
79|
80rnd_plus:
81	swap	%d1			|set up d1 for round prec.
82	tstb	LOCAL_SGN(%a0)		|check for sign
83	bmi	truncate		|if positive then truncate
84	movel	#0xffffffff,%d0		|force g,r,s to be all f's
85	lea	add_to_l,%a1
86	movel	(%a1,%d1.w*4),%a1
87	jmp	(%a1)
88|
89|	ROUND MINUS INFINITY
90|
91|	If sign of fp number = 1 (negative), then add 1 to l.
92|
93rnd_mnus:
94	swap	%d1			|set up d1 for round prec.
95	tstb	LOCAL_SGN(%a0)		|check for sign
96	bpl	truncate		|if negative then truncate
97	movel	#0xffffffff,%d0		|force g,r,s to be all f's
98	lea	add_to_l,%a1
99	movel	(%a1,%d1.w*4),%a1
100	jmp	(%a1)
101|
102|	ROUND ZERO
103|
104|	Always truncate.
105rnd_zero:
106	swap	%d1			|set up d1 for round prec.
107	bra	truncate
108|
109|
110|	ROUND NEAREST
111|
112|	If (g=1), then add 1 to l and if (r=s=0), then clear l
113|	Note that this will round to even in case of a tie.
114|
115rnd_near:
116	swap	%d1			|set up d1 for round prec.
117	asll	#1,%d0			|shift g-bit to c-bit
118	bcc	truncate		|if (g=1) then
119	lea	add_to_l,%a1
120	movel	(%a1,%d1.w*4),%a1
121	jmp	(%a1)
122
123|
124|	ext_grs --- extract guard, round and sticky bits
125|
126| Input:	d1 =		PREC:ROUND
127| Output:	d0{31:29}=	guard, round, sticky
128|
129| The ext_grs extract the guard/round/sticky bits according to the
130| selected rounding precision. It is called by the round subroutine
131| only.  All registers except d0 are kept intact. d0 becomes an
132| updated guard,round,sticky in d0{31:29}
133|
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.
136|
137ext_grs:
138	swap	%d1			|have d1.w point to round precision
139	cmpiw	#0,%d1
140	bnes	sgl_or_dbl
141	bras	end_ext_grs
142
143sgl_or_dbl:
144	moveml	%d2/%d3,-(%a7)		|make some temp registers
145	cmpiw	#1,%d1
146	bnes	grs_dbl
147grs_sgl:
148	bfextu	LOCAL_HI(%a0){#24:#2},%d3	|sgl prec. g-r are 2 bits right
149	movel	#30,%d2			|of the sgl prec. limits
150	lsll	%d2,%d3			|shift g-r bits to MSB of d3
151	movel	LOCAL_HI(%a0),%d2		|get word 2 for s-bit test
152	andil	#0x0000003f,%d2		|s bit is the or of all other
153	bnes	st_stky			|bits to the right of g-r
154	tstl	LOCAL_LO(%a0)		|test lower mantissa
155	bnes	st_stky			|if any are set, set sticky
156	tstl	%d0			|test original g,r,s
157	bnes	st_stky			|if any are set, set sticky
158	bras	end_sd			|if words 3 and 4 are clr, exit
159grs_dbl:
160	bfextu	LOCAL_LO(%a0){#21:#2},%d3	|dbl-prec. g-r are 2 bits right
161	movel	#30,%d2			|of the dbl prec. limits
162	lsll	%d2,%d3			|shift g-r bits to the MSB of d3
163	movel	LOCAL_LO(%a0),%d2		|get lower mantissa  for s-bit test
164	andil	#0x000001ff,%d2		|s bit is the or-ing of all
165	bnes	st_stky			|other bits to the right of g-r
166	tstl	%d0			|test word original g,r,s
167	bnes	st_stky			|if any are set, set sticky
168	bras	end_sd			|if clear, exit
169st_stky:
170	bset	#rnd_stky_bit,%d3
171end_sd:
172	movel	%d3,%d0			|return grs to d0
173	moveml	(%a7)+,%d2/%d3		|restore scratch registers
174end_ext_grs:
175	swap	%d1			|restore d1 to original
176	rts
177
178|*******************  Local Equates
179	.set	ad_1_sgl,0x00000100	|  constant to add 1 to l-bit in sgl prec
180	.set	ad_1_dbl,0x00000800	|  constant to add 1 to l-bit in dbl prec
181
182
183|Jump table for adding 1 to the l-bit indexed by rnd prec
184
185add_to_l:
186	.long	add_ext
187	.long	add_sgl
188	.long	add_dbl
189	.long	add_dbl
190|
191|	ADD SINGLE
192|
193add_sgl:
194	addl	#ad_1_sgl,LOCAL_HI(%a0)
195	bccs	scc_clr			|no mantissa overflow
196	roxrw  LOCAL_HI(%a0)		|shift v-bit back in
197	roxrw  LOCAL_HI+2(%a0)		|shift v-bit back in
198	addw	#0x1,LOCAL_EX(%a0)	|and incr exponent
199scc_clr:
200	tstl	%d0			|test for rs = 0
201	bnes	sgl_done
202	andiw  #0xfe00,LOCAL_HI+2(%a0)	|clear the l-bit
203sgl_done:
204	andil	#0xffffff00,LOCAL_HI(%a0) |truncate bits beyond sgl limit
205	clrl	LOCAL_LO(%a0)		|clear d2
206	rts
207
208|
209|	ADD EXTENDED
210|
211add_ext:
212	addql  #1,LOCAL_LO(%a0)		|add 1 to l-bit
213	bccs	xcc_clr			|test for carry out
214	addql  #1,LOCAL_HI(%a0)		|propagate carry
215	bccs	xcc_clr
216	roxrw  LOCAL_HI(%a0)		|mant is 0 so restore v-bit
217	roxrw  LOCAL_HI+2(%a0)		|mant is 0 so restore v-bit
218	roxrw	LOCAL_LO(%a0)
219	roxrw	LOCAL_LO+2(%a0)
220	addw	#0x1,LOCAL_EX(%a0)	|and inc exp
221xcc_clr:
222	tstl	%d0			|test rs = 0
223	bnes	add_ext_done
224	andib	#0xfe,LOCAL_LO+3(%a0)	|clear the l bit
225add_ext_done:
226	rts
227|
228|	ADD DOUBLE
229|
230add_dbl:
231	addl	#ad_1_dbl,LOCAL_LO(%a0)
232	bccs	dcc_clr
233	addql	#1,LOCAL_HI(%a0)		|propagate carry
234	bccs	dcc_clr
235	roxrw	LOCAL_HI(%a0)		|mant is 0 so restore v-bit
236	roxrw	LOCAL_HI+2(%a0)		|mant is 0 so restore v-bit
237	roxrw	LOCAL_LO(%a0)
238	roxrw	LOCAL_LO+2(%a0)
239	addw	#0x1,LOCAL_EX(%a0)	|incr exponent
240dcc_clr:
241	tstl	%d0			|test for rs = 0
242	bnes	dbl_done
243	andiw	#0xf000,LOCAL_LO+2(%a0)	|clear the l-bit
244
245dbl_done:
246	andil	#0xfffff800,LOCAL_LO(%a0) |truncate bits beyond dbl limit
247	rts
248
249error:
250	rts
251|
252| Truncate all other bits
253|
254trunct:
255	.long	end_rnd
256	.long	sgl_done
257	.long	dbl_done
258	.long	dbl_done
259
260truncate:
261	lea	trunct,%a1
262	movel	(%a1,%d1.w*4),%a1
263	jmp	(%a1)
264
265end_rnd:
266	rts
267
268|
269|	NORMALIZE
270|
271| These routines (nrm_zero & nrm_set) normalize the unnorm.  This
272| is done by shifting the mantissa left while decrementing the
273| exponent.
274|
275| NRM_SET shifts and decrements until there is a 1 set in the integer
276| bit of the mantissa (msb in d1).
277|
278| NRM_ZERO shifts and decrements until there is a 1 set in the integer
279| bit of the mantissa (msb in d1) unless this would mean the exponent
280| would go less than 0.  In that case the number becomes a denorm - the
281| exponent (d0) is set to 0 and the mantissa (d1 & d2) is not
282| normalized.
283|
284| Note that both routines have been optimized (for the worst case) and
285| therefore do not have the easy to follow decrement/shift loop.
286|
287|	NRM_ZERO
288|
289|	Distance to first 1 bit in mantissa = X
290|	Distance to 0 from exponent = Y
291|	If X < Y
292|	Then
293|	  nrm_set
294|	Else
295|	  shift mantissa by Y
296|	  set exponent = 0
297|
298|input:
299|	FP_SCR1 = exponent, ms mantissa part, ls mantissa part
300|output:
301|	L_SCR1{4} = fpte15 or ete15 bit
302|
303	.global	nrm_zero
304nrm_zero:
305	movew	LOCAL_EX(%a0),%d0
306	cmpw   #64,%d0          |see if exp > 64
307	bmis	d0_less
308	bsr	nrm_set		|exp > 64 so exp won't exceed 0
309	rts
310d0_less:
311	moveml	%d2/%d3/%d5/%d6,-(%a7)
312	movel	LOCAL_HI(%a0),%d1
313	movel	LOCAL_LO(%a0),%d2
314
315	bfffo	%d1{#0:#32},%d3	|get the distance to the first 1
316|				;in ms mant
317	beqs	ms_clr		|branch if no bits were set
318	cmpw	%d3,%d0		|of X>Y
319	bmis	greater		|then exp will go past 0 (neg) if
320|				;it is just shifted
321	bsr	nrm_set		|else exp won't go past 0
322	moveml	(%a7)+,%d2/%d3/%d5/%d6
323	rts
324greater:
325	movel	%d2,%d6		|save ls mant in d6
326	lsll	%d0,%d2		|shift ls mant by count
327	lsll	%d0,%d1		|shift ms mant by count
328	movel	#32,%d5
329	subl	%d0,%d5		|make op a denorm by shifting bits
330	lsrl	%d5,%d6		|by the number in the exp, then
331|				;set exp = 0.
332	orl	%d6,%d1		|shift the ls mant bits into the ms mant
333	movel	#0,%d0		|same as if decremented exp to 0
334|				;while shifting
335	movew	%d0,LOCAL_EX(%a0)
336	movel	%d1,LOCAL_HI(%a0)
337	movel	%d2,LOCAL_LO(%a0)
338	moveml	(%a7)+,%d2/%d3/%d5/%d6
339	rts
340ms_clr:
341	bfffo	%d2{#0:#32},%d3	|check if any bits set in ls mant
342	beqs	all_clr		|branch if none set
343	addw	#32,%d3
344	cmpw	%d3,%d0		|if X>Y
345	bmis	greater		|then branch
346	bsr	nrm_set		|else exp won't go past 0
347	moveml	(%a7)+,%d2/%d3/%d5/%d6
348	rts
349all_clr:
350	movew	#0,LOCAL_EX(%a0)	|no mantissa bits set. Set exp = 0.
351	moveml	(%a7)+,%d2/%d3/%d5/%d6
352	rts
353|
354|	NRM_SET
355|
356	.global	nrm_set
357nrm_set:
358	movel	%d7,-(%a7)
359	bfffo	LOCAL_HI(%a0){#0:#32},%d7 |find first 1 in ms mant to d7)
360	beqs	lower		|branch if ms mant is all 0's
361
362	movel	%d6,-(%a7)
363
364	subw	%d7,LOCAL_EX(%a0)	|sub exponent by count
365	movel	LOCAL_HI(%a0),%d0	|d0 has ms mant
366	movel	LOCAL_LO(%a0),%d1 |d1 has ls mant
367
368	lsll	%d7,%d0		|shift first 1 to j bit position
369	movel	%d1,%d6		|copy ls mant into d6
370	lsll	%d7,%d6		|shift ls mant by count
371	movel	%d6,LOCAL_LO(%a0)	|store ls mant into memory
372	moveql	#32,%d6
373	subl	%d7,%d6		|continue shift
374	lsrl	%d6,%d1		|shift off all bits but those that will
375|				;be shifted into ms mant
376	orl	%d1,%d0		|shift the ls mant bits into the ms mant
377	movel	%d0,LOCAL_HI(%a0)	|store ms mant into memory
378	moveml	(%a7)+,%d7/%d6	|restore registers
379	rts
380
381|
382| We get here if ms mant was = 0, and we assume ls mant has bits
383| set (otherwise this would have been tagged a zero not a denorm).
384|
385lower:
386	movew	LOCAL_EX(%a0),%d0	|d0 has exponent
387	movel	LOCAL_LO(%a0),%d1	|d1 has ls mant
388	subw	#32,%d0		|account for ms mant being all zeros
389	bfffo	%d1{#0:#32},%d7	|find first 1 in ls mant to d7)
390	subw	%d7,%d0		|subtract shift count from exp
391	lsll	%d7,%d1		|shift first 1 to integer bit in ms mant
392	movew	%d0,LOCAL_EX(%a0)	|store ms mant
393	movel	%d1,LOCAL_HI(%a0)	|store exp
394	clrl	LOCAL_LO(%a0)	|clear ls mant
395	movel	(%a7)+,%d7
396	rts
397|
398|	denorm --- denormalize an intermediate result
399|
400|	Used by underflow.
401|
402| Input:
403|	a0	 points to the operand to be denormalized
404|		 (in the internal extended format)
405|
406|	d0:	 rounding precision
407| Output:
408|	a0	 points to the denormalized result
409|		 (in the internal extended format)
410|
411|	d0	is guard,round,sticky
412|
413| d0 comes into this routine with the rounding precision. It
414| is then loaded with the denormalized exponent threshold for the
415| rounding precision.
416|
417
418	.global	denorm
419denorm:
420	btstb	#6,LOCAL_EX(%a0)	|check for exponents between $7fff-$4000
421	beqs	no_sgn_ext
422	bsetb	#7,LOCAL_EX(%a0)	|sign extend if it is so
423no_sgn_ext:
424
425	cmpib	#0,%d0		|if 0 then extended precision
426	bnes	not_ext		|else branch
427
428	clrl	%d1		|load d1 with ext threshold
429	clrl	%d0		|clear the sticky flag
430	bsr	dnrm_lp		|denormalize the number
431	tstb	%d1		|check for inex
432	beq	no_inex		|if clr, no inex
433	bras	dnrm_inex	|if set, set inex
434
435not_ext:
436	cmpil	#1,%d0		|if 1 then single precision
437	beqs	load_sgl	|else must be 2, double prec
438
439load_dbl:
440	movew	#dbl_thresh,%d1	|put copy of threshold in d1
441	movel	%d1,%d0		|copy d1 into d0
442	subw	LOCAL_EX(%a0),%d0	|diff = threshold - exp
443	cmpw	#67,%d0		|if diff > 67 (mant + grs bits)
444	bpls	chk_stky	|then branch (all bits would be
445|				; shifted off in denorm routine)
446	clrl	%d0		|else clear the sticky flag
447	bsr	dnrm_lp		|denormalize the number
448	tstb	%d1		|check flag
449	beqs	no_inex		|if clr, no inex
450	bras	dnrm_inex	|if set, set inex
451
452load_sgl:
453	movew	#sgl_thresh,%d1	|put copy of threshold in d1
454	movel	%d1,%d0		|copy d1 into d0
455	subw	LOCAL_EX(%a0),%d0	|diff = threshold - exp
456	cmpw	#67,%d0		|if diff > 67 (mant + grs bits)
457	bpls	chk_stky	|then branch (all bits would be
458|				; shifted off in denorm routine)
459	clrl	%d0		|else clear the sticky flag
460	bsr	dnrm_lp		|denormalize the number
461	tstb	%d1		|check flag
462	beqs	no_inex		|if clr, no inex
463	bras	dnrm_inex	|if set, set inex
464
465chk_stky:
466	tstl	LOCAL_HI(%a0)	|check for any bits set
467	bnes	set_stky
468	tstl	LOCAL_LO(%a0)	|check for any bits set
469	bnes	set_stky
470	bras	clr_mant
471set_stky:
472	orl	#inx2a_mask,USER_FPSR(%a6) |set inex2/ainex
473	movel	#0x20000000,%d0	|set sticky bit in return value
474clr_mant:
475	movew	%d1,LOCAL_EX(%a0)		|load exp with threshold
476	movel	#0,LOCAL_HI(%a0)	|set d1 = 0 (ms mantissa)
477	movel	#0,LOCAL_LO(%a0)		|set d2 = 0 (ms mantissa)
478	rts
479dnrm_inex:
480	orl	#inx2a_mask,USER_FPSR(%a6) |set inex2/ainex
481no_inex:
482	rts
483
484|
485|	dnrm_lp --- normalize exponent/mantissa to specified threshold
486|
487| Input:
488|	a0		points to the operand to be denormalized
489|	d0{31:29}	initial guard,round,sticky
490|	d1{15:0}	denormalization threshold
491| Output:
492|	a0		points to the denormalized operand
493|	d0{31:29}	final guard,round,sticky
494|	d1.b		inexact flag:  all ones means inexact result
495|
496| The LOCAL_LO and LOCAL_GRS parts of the value are copied to FP_SCR2
497| so that bfext can be used to extract the new low part of the mantissa.
498| Dnrm_lp can be called with a0 pointing to ETEMP or WBTEMP and there
499| is no LOCAL_GRS scratch word following it on the fsave frame.
500|
501	.global	dnrm_lp
502dnrm_lp:
503	movel	%d2,-(%sp)		|save d2 for temp use
504	btstb	#E3,E_BYTE(%a6)		|test for type E3 exception
505	beqs	not_E3			|not type E3 exception
506	bfextu	WBTEMP_GRS(%a6){#6:#3},%d2	|extract guard,round, sticky  bit
507	movel	#29,%d0
508	lsll	%d0,%d2			|shift g,r,s to their positions
509	movel	%d2,%d0
510not_E3:
511	movel	(%sp)+,%d2		|restore d2
512	movel	LOCAL_LO(%a0),FP_SCR2+LOCAL_LO(%a6)
513	movel	%d0,FP_SCR2+LOCAL_GRS(%a6)
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
522|
523| No normalization necessary
524|
525no_lp:
526	clrb	%d1			|set no inex2 reported
527	movel	FP_SCR2+LOCAL_GRS(%a6),%d0	|restore original g,r,s
528	rts
529|
530| case (0<d1<32)
531|
532case_1:
533	movel	%d2,-(%sp)
534	movew	%d0,LOCAL_EX(%a0)		|exponent = denorm threshold
535	movel	#32,%d0
536	subw	%d1,%d0			|d0 = 32 - d1
537	bfextu	LOCAL_EX(%a0){%d0:#32},%d2
538	bfextu	%d2{%d1:%d0},%d2		|d2 = new LOCAL_HI
539	bfextu	LOCAL_HI(%a0){%d0:#32},%d1	|d1 = new LOCAL_LO
540	bfextu	FP_SCR2+LOCAL_LO(%a6){%d0:#32},%d0	|d0 = new G,R,S
541	movel	%d2,LOCAL_HI(%a0)		|store new LOCAL_HI
542	movel	%d1,LOCAL_LO(%a0)		|store new LOCAL_LO
543	clrb	%d1
544	bftst	%d0{#2:#30}
545	beqs	c1nstky
546	bsetl	#rnd_stky_bit,%d0
547	st	%d1
548c1nstky:
549	movel	FP_SCR2+LOCAL_GRS(%a6),%d2	|restore original g,r,s
550	andil	#0xe0000000,%d2		|clear all but G,R,S
551	tstl	%d2			|test if original G,R,S are clear
552	beqs	grs_clear
553	orl	#0x20000000,%d0		|set sticky bit in d0
554grs_clear:
555	andil	#0xe0000000,%d0		|clear all but G,R,S
556	movel	(%sp)+,%d2
557	rts
558|
559| case (32<=d1<64)
560|
561case_2:
562	movel	%d2,-(%sp)
563	movew	%d0,LOCAL_EX(%a0)		|unsigned exponent = threshold
564	subw	#32,%d1			|d1 now between 0 and 32
565	movel	#32,%d0
566	subw	%d1,%d0			|d0 = 32 - d1
567	bfextu	LOCAL_EX(%a0){%d0:#32},%d2
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}
571	bnes	c2_sstky		|bra if sticky bit to be set
572	bftst	FP_SCR2+LOCAL_LO(%a6){%d0:#32}
573	bnes	c2_sstky		|bra if sticky bit to be set
574	movel	%d1,%d0
575	clrb	%d1
576	bras	end_c2
577c2_sstky:
578	movel	%d1,%d0
579	bsetl	#rnd_stky_bit,%d0
580	st	%d1
581end_c2:
582	clrl	LOCAL_HI(%a0)		|store LOCAL_HI = 0
583	movel	%d2,LOCAL_LO(%a0)		|store LOCAL_LO
584	movel	FP_SCR2+LOCAL_GRS(%a6),%d2	|restore original g,r,s
585	andil	#0xe0000000,%d2		|clear all but G,R,S
586	tstl	%d2			|test if original G,R,S are clear
587	beqs	clear_grs
588	orl	#0x20000000,%d0		|set sticky bit in d0
589clear_grs:
590	andil	#0xe0000000,%d0		|get rid of all but G,R,S
591	movel	(%sp)+,%d2
592	rts
593|
594| d1 >= 64 Force the exponent to be the denorm threshold with the
595| correct sign.
596|
597case_3:
598	movew	%d0,LOCAL_EX(%a0)
599	tstw	LOCAL_SGN(%a0)
600	bges	c3con
601c3neg:
602	orl	#0x80000000,LOCAL_EX(%a0)
603c3con:
604	cmpw	#64,%d1
605	beqs	sixty_four
606	cmpw	#65,%d1
607	beqs	sixty_five
608|
609| Shift value is out of range.  Set d1 for inex2 flag and
610| return a zero with the given threshold.
611|
612	clrl	LOCAL_HI(%a0)
613	clrl	LOCAL_LO(%a0)
614	movel	#0x20000000,%d0
615	st	%d1
616	rts
617
618sixty_four:
619	movel	LOCAL_HI(%a0),%d0
620	bfextu	%d0{#2:#30},%d1
621	andil	#0xc0000000,%d0
622	bras	c3com
623
624sixty_five:
625	movel	LOCAL_HI(%a0),%d0
626	bfextu	%d0{#1:#31},%d1
627	andil	#0x80000000,%d0
628	lsrl	#1,%d0			|shift high bit into R bit
629
630c3com:
631	tstl	%d1
632	bnes	c3ssticky
633	tstl	LOCAL_LO(%a0)
634	bnes	c3ssticky
635	tstb	FP_SCR2+LOCAL_GRS(%a6)
636	bnes	c3ssticky
637	clrb	%d1
638	bras	c3end
639
640c3ssticky:
641	bsetl	#rnd_stky_bit,%d0
642	st	%d1
643c3end:
644	clrl	LOCAL_HI(%a0)
645	clrl	LOCAL_LO(%a0)
646	rts
647
648	|end
649