1 |
2 | kernel_ex.sa 3.3 12/19/90
3 |
4 | This file contains routines to force exception status in the
5 | fpu for exceptional cases detected or reported within the
6 | transcendental functions. Typically, the t_xx routine will
7 | set the appropriate bits in the USER_FPSR word on the stack.
8 | The bits are tested in gen_except.sa to determine if an exceptional
9 | situation needs to be created on return from the FPSP.
10 |
11
12 | Copyright (C) Motorola, Inc. 1990
13 | All Rights Reserved
14 |
15 | THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
16 | The copyright notice above does not evidence any
17 | actual or intended publication of such source code.
18
19 KERNEL_EX: |idnt 2,1 | Motorola 040 Floating Point Software Package
20
21 |section 8
22
23 .include "fpsp.h"
24
25 mns_inf: .long 0xffff0000,0x00000000,0x00000000
26 pls_inf: .long 0x7fff0000,0x00000000,0x00000000
27 nan: .long 0x7fff0000,0xffffffff,0xffffffff
28 huge: .long 0x7ffe0000,0xffffffff,0xffffffff
29
30 |xref ovf_r_k
31 |xref unf_sub
32 |xref nrm_set
33
34 .global t_dz
35 .global t_dz2
36 .global t_operr
37 .global t_unfl
38 .global t_ovfl
39 .global t_ovfl2
40 .global t_inx2
41 .global t_frcinx
42 .global t_extdnrm
43 .global t_resdnrm
44 .global dst_nan
45 .global src_nan
46 |
47 | DZ exception
48 |
49 |
50 | if dz trap disabled
51 | store properly signed inf (use sign of etemp) into fp0
52 | set FPSR exception status dz bit, condition code
53 | inf bit, and accrued dz bit
54 | return
55 | frestore the frame into the machine (done by unimp_hd)
56 |
57 | else dz trap enabled
58 | set exception status bit & accrued bits in FPSR
59 | set flag to disable sto_res from corrupting fp register
60 | return
61 | frestore the frame into the machine (done by unimp_hd)
62 |
63 | t_dz2 is used by monadic functions such as flogn (from do_func).
64 | t_dz is used by monadic functions such as satanh (from the
65 | transcendental function).
66 |
67 t_dz2:
68 bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
69 fmovel #0,%FPSR |clr status bits (Z set)
70 btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
71 bnes dz_ena_end
72 bras m_inf |flogx always returns -inf
73 t_dz:
74 fmovel #0,%FPSR |clr status bits (Z set)
75 btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
76 bnes dz_ena
77 |
78 | dz disabled
79 |
80 btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
81 beqs p_inf |branch if pos sign
82
83 m_inf:
84 fmovemx mns_inf,%fp0-%fp0 |load -inf
85 bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
86 bras set_fpsr
87 p_inf:
88 fmovemx pls_inf,%fp0-%fp0 |load +inf
89 set_fpsr:
90 orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
91 rts
92 |
93 | dz enabled
94 |
95 dz_ena:
96 btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
97 beqs dz_ena_end
98 bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
99 dz_ena_end:
100 orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
101 st STORE_FLG(%a6)
102 rts
103 |
104 | OPERR exception
105 |
106 | if (operr trap disabled)
107 | set FPSR exception status operr bit, condition code
108 | nan bit; Store default NAN into fp0
109 | frestore the frame into the machine (done by unimp_hd)
110 |
111 | else (operr trap enabled)
112 | set FPSR exception status operr bit, accrued operr bit
113 | set flag to disable sto_res from corrupting fp register
114 | frestore the frame into the machine (done by unimp_hd)
115 |
116 t_operr:
117 orl #opnan_mask,USER_FPSR(%a6) |set NaN, OPERR, AIOP
118
119 btstb #operr_bit,FPCR_ENABLE(%a6) |test FPCR for operr enabled
120 bnes op_ena
121
122 fmovemx nan,%fp0-%fp0 |load default nan
123 rts
124 op_ena:
125 st STORE_FLG(%a6) |do not corrupt destination
126 rts
127
128 |
129 | t_unfl --- UNFL exception
130 |
131 | This entry point is used by all routines requiring unfl, inex2,
132 | aunfl, and ainex to be set on exit.
133 |
134 | On entry, a0 points to the exceptional operand. The final exceptional
135 | operand is built in FP_SCR1 and only the sign from the original operand
136 | is used.
137 |
138 t_unfl:
139 clrl FP_SCR1(%a6) |set exceptional operand to zero
140 clrl FP_SCR1+4(%a6)
141 clrl FP_SCR1+8(%a6)
142 tstb (%a0) |extract sign from caller's exop
143 bpls unfl_signok
144 bset #sign_bit,FP_SCR1(%a6)
145 unfl_signok:
146 leal FP_SCR1(%a6),%a0
147 orl #unfinx_mask,USER_FPSR(%a6)
148 | ;set UNFL, INEX2, AUNFL, AINEX
149 unfl_con:
150 btstb #unfl_bit,FPCR_ENABLE(%a6)
151 beqs unfl_dis
152
153 unfl_ena:
154 bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
155 bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
156 bsetb #sticky_bit,STICKY(%a6) |set sticky bit
157
158 bclrb #E1,E_BYTE(%a6)
159
160 unfl_dis:
161 bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
162
163 bclrb #sign_bit,LOCAL_EX(%a0)
164 sne LOCAL_SGN(%a0) |convert to internal ext format
165
166 bsr unf_sub |returns IEEE result at a0
167 | ;and sets FPSR_CC accordingly
168
169 bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
170 beqs unfl_fin
171
172 bsetb #sign_bit,LOCAL_EX(%a0)
173 bsetb #sign_bit,FP_SCR1(%a6) |set sign bit of exc operand
174
175 unfl_fin:
176 fmovemx (%a0),%fp0-%fp0 |store result in fp0
177 rts
178
179
180 |
181 | t_ovfl2 --- OVFL exception (without inex2 returned)
182 |
183 | This entry is used by scale to force catastrophic overflow. The
184 | ovfl, aovfl, and ainex bits are set, but not the inex2 bit.
185 |
186 t_ovfl2:
187 orl #ovfl_inx_mask,USER_FPSR(%a6)
188 movel ETEMP(%a6),FP_SCR1(%a6)
189 movel ETEMP_HI(%a6),FP_SCR1+4(%a6)
190 movel ETEMP_LO(%a6),FP_SCR1+8(%a6)
191 |
192 | Check for single or double round precision. If single, check if
193 | the lower 40 bits of ETEMP are zero; if not, set inex2. If double,
194 | check if the lower 21 bits are zero; if not, set inex2.
195 |
196 moveb FPCR_MODE(%a6),%d0
197 andib #0xc0,%d0
198 beq t_work |if extended, finish ovfl processing
199 cmpib #0x40,%d0 |test for single
200 bnes t_dbl
201 t_sgl:
202 tstb ETEMP_LO(%a6)
203 bnes t_setinx2
204 movel ETEMP_HI(%a6),%d0
205 andil #0xff,%d0 |look at only lower 8 bits
206 bnes t_setinx2
207 bra t_work
208 t_dbl:
209 movel ETEMP_LO(%a6),%d0
210 andil #0x7ff,%d0 |look at only lower 11 bits
211 beq t_work
212 t_setinx2:
213 orl #inex2_mask,USER_FPSR(%a6)
214 bras t_work
215 |
216 | t_ovfl --- OVFL exception
217 |
218 |** Note: the exc operand is returned in ETEMP.
219 |
220 t_ovfl:
221 orl #ovfinx_mask,USER_FPSR(%a6)
222 t_work:
223 btstb #ovfl_bit,FPCR_ENABLE(%a6) |test FPCR for ovfl enabled
224 beqs ovf_dis
225
226 ovf_ena:
227 clrl FP_SCR1(%a6) |set exceptional operand
228 clrl FP_SCR1+4(%a6)
229 clrl FP_SCR1+8(%a6)
230
231 bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
232 bclrb #wbtemp15_bit,WB_BYTE(%a6) |clear wbtemp15
233 bsetb #sticky_bit,STICKY(%a6) |set sticky bit
234
235 bclrb #E1,E_BYTE(%a6)
236 | ;fall through to disabled case
237
238 | For disabled overflow call 'ovf_r_k'. This routine loads the
239 | correct result based on the rounding precision, destination
240 | format, rounding mode and sign.
241 |
242 ovf_dis:
243 bsr ovf_r_k |returns unsigned ETEMP_EX
244 | ;and sets FPSR_CC accordingly.
245 bfclr ETEMP_SGN(%a6){#0:#8} |fix sign
246 beqs ovf_pos
247 bsetb #sign_bit,ETEMP_EX(%a6)
248 bsetb #sign_bit,FP_SCR1(%a6) |set exceptional operand sign
249 ovf_pos:
250 fmovemx ETEMP(%a6),%fp0-%fp0 |move the result to fp0
251 rts
252
253
254 |
255 | INEX2 exception
256 |
257 | The inex2 and ainex bits are set.
258 |
259 t_inx2:
260 orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
261 rts
262
263 |
264 | Force Inex2
265 |
266 | This routine is called by the transcendental routines to force
267 | the inex2 exception bits set in the FPSR. If the underflow bit
268 | is set, but the underflow trap was not taken, the aunfl bit in
269 | the FPSR must be set.
270 |
271 t_frcinx:
272 orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
273 btstb #unfl_bit,FPSR_EXCEPT(%a6) |test for unfl bit set
274 beqs no_uacc1 |if clear, do not set aunfl
275 bsetb #aunfl_bit,FPSR_AEXCEPT(%a6)
276 no_uacc1:
277 rts
278
279 |
280 | DST_NAN
281 |
282 | Determine if the destination nan is signalling or non-signalling,
283 | and set the FPSR bits accordingly. See the MC68040 User's Manual
284 | section 3.2.2.5 NOT-A-NUMBERS.
285 |
286 dst_nan:
287 btstb #sign_bit,FPTEMP_EX(%a6) |test sign of nan
288 beqs dst_pos |if clr, it was positive
289 bsetb #neg_bit,FPSR_CC(%a6) |set N bit
290 dst_pos:
291 btstb #signan_bit,FPTEMP_HI(%a6) |check if signalling
292 beqs dst_snan |branch if signalling
293
294 fmovel %d1,%fpcr |restore user's rmode/prec
295 fmovex FPTEMP(%a6),%fp0 |return the non-signalling nan
296 |
297 | Check the source nan. If it is signalling, snan will be reported.
298 |
299 moveb STAG(%a6),%d0
300 andib #0xe0,%d0
301 cmpib #0x60,%d0
302 bnes no_snan
303 btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
304 bnes no_snan
305 orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
306 no_snan:
307 rts
308
309 dst_snan:
310 btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
311 beqs dst_dis |branch if disabled
312
313 orb #nan_tag,DTAG(%a6) |set up dtag for nan
314 st STORE_FLG(%a6) |do not store a result
315 orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
316 rts
317
318 dst_dis:
319 bsetb #signan_bit,FPTEMP_HI(%a6) |set SNAN bit in sop
320 fmovel %d1,%fpcr |restore user's rmode/prec
321 fmovex FPTEMP(%a6),%fp0 |load non-sign. nan
322 orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
323 rts
324
325 |
326 | SRC_NAN
327 |
328 | Determine if the source nan is signalling or non-signalling,
329 | and set the FPSR bits accordingly. See the MC68040 User's Manual
330 | section 3.2.2.5 NOT-A-NUMBERS.
331 |
332 src_nan:
333 btstb #sign_bit,ETEMP_EX(%a6) |test sign of nan
334 beqs src_pos |if clr, it was positive
335 bsetb #neg_bit,FPSR_CC(%a6) |set N bit
336 src_pos:
337 btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
338 beqs src_snan |branch if signalling
339 fmovel %d1,%fpcr |restore user's rmode/prec
340 fmovex ETEMP(%a6),%fp0 |return the non-signalling nan
341 rts
342
343 src_snan:
344 btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
345 beqs src_dis |branch if disabled
346 bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
347 orb #norm_tag,DTAG(%a6) |set up dtag for norm
348 orb #nan_tag,STAG(%a6) |set up stag for nan
349 st STORE_FLG(%a6) |do not store a result
350 orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
351 rts
352
353 src_dis:
354 bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
355 fmovel %d1,%fpcr |restore user's rmode/prec
356 fmovex ETEMP(%a6),%fp0 |load non-sign. nan
357 orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
358 rts
359
360 |
361 | For all functions that have a denormalized input and that f(x)=x,
362 | this is the entry point
363 |
364 t_extdnrm:
365 orl #unfinx_mask,USER_FPSR(%a6)
366 | ;set UNFL, INEX2, AUNFL, AINEX
367 bras xdnrm_con
368 |
369 | Entry point for scale with extended denorm. The function does
370 | not set inex2, aunfl, or ainex.
371 |
372 t_resdnrm:
373 orl #unfl_mask,USER_FPSR(%a6)
374
375 xdnrm_con:
376 btstb #unfl_bit,FPCR_ENABLE(%a6)
377 beqs xdnrm_dis
378
379 |
380 | If exceptions are enabled, the additional task of setting up WBTEMP
381 | is needed so that when the underflow exception handler is entered,
382 | the user perceives no difference between what the 040 provides vs.
383 | what the FPSP provides.
384 |
385 xdnrm_ena:
386 movel %a0,-(%a7)
387
388 movel LOCAL_EX(%a0),FP_SCR1(%a6)
389 movel LOCAL_HI(%a0),FP_SCR1+4(%a6)
390 movel LOCAL_LO(%a0),FP_SCR1+8(%a6)
391
392 lea FP_SCR1(%a6),%a0
393
394 bclrb #sign_bit,LOCAL_EX(%a0)
395 sne LOCAL_SGN(%a0) |convert to internal ext format
396 tstw LOCAL_EX(%a0) |check if input is denorm
397 beqs xdnrm_dn |if so, skip nrm_set
398 bsr nrm_set |normalize the result (exponent
399 | ;will be negative
400 xdnrm_dn:
401 bclrb #sign_bit,LOCAL_EX(%a0) |take off false sign
402 bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
403 beqs xdep
404 bsetb #sign_bit,LOCAL_EX(%a0)
405 xdep:
406 bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
407 bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
408 bclrb #sticky_bit,STICKY(%a6) |clear sticky bit
409 bclrb #E1,E_BYTE(%a6)
410 movel (%a7)+,%a0
411 xdnrm_dis:
412 bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
413 bnes not_ext |if not round extended, store
414 | ;IEEE defaults
415 is_ext:
416 btstb #sign_bit,LOCAL_EX(%a0)
417 beqs xdnrm_store
418
419 bsetb #neg_bit,FPSR_CC(%a6) |set N bit in FPSR_CC
420
421 bras xdnrm_store
422
423 not_ext:
424 bclrb #sign_bit,LOCAL_EX(%a0)
425 sne LOCAL_SGN(%a0) |convert to internal ext format
426 bsr unf_sub |returns IEEE result pointed by
427 | ;a0; sets FPSR_CC accordingly
428 bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
429 beqs xdnrm_store
430 bsetb #sign_bit,LOCAL_EX(%a0)
431 xdnrm_store:
432 fmovemx (%a0),%fp0-%fp0 |store result in fp0
433 rts
434
435 |
436 | This subroutine is used for dyadic operations that use an extended
437 | denorm within the kernel. The approach used is to capture the frame,
438 | fix/restore.
439 |
440 .global t_avoid_unsupp
441 t_avoid_unsupp:
442 link %a2,#-LOCAL_SIZE |so that a2 fpsp.h negative
443 | ;offsets may be used
444 fsave -(%a7)
445 tstb 1(%a7) |check if idle, exit if so
446 beq idle_end
447 btstb #E1,E_BYTE(%a2) |check for an E1 exception if
448 | ;enabled, there is an unsupp
449 beq end_avun |else, exit
450 btstb #7,DTAG(%a2) |check for denorm destination
451 beqs src_den |else, must be a source denorm
452 |
453 | handle destination denorm
454 |
455 lea FPTEMP(%a2),%a0
456 btstb #sign_bit,LOCAL_EX(%a0)
457 sne LOCAL_SGN(%a0) |convert to internal ext format
458 bclrb #7,DTAG(%a2) |set DTAG to norm
459 bsr nrm_set |normalize result, exponent
460 | ;will become negative
461 bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
462 bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
463 beqs ck_src_den |check if source is also denorm
464 bsetb #sign_bit,LOCAL_EX(%a0)
465 ck_src_den:
466 btstb #7,STAG(%a2)
467 beqs end_avun
468 src_den:
469 lea ETEMP(%a2),%a0
470 btstb #sign_bit,LOCAL_EX(%a0)
471 sne LOCAL_SGN(%a0) |convert to internal ext format
472 bclrb #7,STAG(%a2) |set STAG to norm
473 bsr nrm_set |normalize result, exponent
474 | ;will become negative
475 bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
476 bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
477 beqs den_com
478 bsetb #sign_bit,LOCAL_EX(%a0)
479 den_com:
480 moveb #0xfe,CU_SAVEPC(%a2) |set continue frame
481 clrw NMNEXC(%a2) |clear NMNEXC
482 bclrb #E1,E_BYTE(%a2)
483 | fmove.l %FPSR,FPSR_SHADOW(%a2)
484 | bset.b #SFLAG,E_BYTE(%a2)
485 | bset.b #XFLAG,T_BYTE(%a2)
486 end_avun:
487 frestore (%a7)+
488 unlk %a2
489 rts
490 idle_end:
491 addl #4,%a7
492 unlk %a2
493 rts
494 |end
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