1 |
2 | x_operr.sa 3.5 7/1/91
3 |
4 | fpsp_operr --- FPSP handler for operand error exception
5 |
6 | See 68040 User's Manual pp. 9-44f
7 |
8 | Note 1: For trap disabled 040 does the following:
9 | If the dest is a fp reg, then an extended precision non_signaling
10 | NAN is stored in the dest reg. If the dest format is b, w, or l and
11 | the source op is a NAN, then garbage is stored as the result (actually
12 | the upper 32 bits of the mantissa are sent to the integer unit). If
13 | the dest format is integer (b, w, l) and the operr is caused by
14 | integer overflow, or the source op is inf, then the result stored is
15 | garbage.
16 | There are three cases in which operr is incorrectly signaled on the
17 | 040. This occurs for move_out of format b, w, or l for the largest
18 | negative integer (-2^7 for b, -2^15 for w, -2^31 for l).
19 |
20 | On opclass = 011 fmove.(b,w,l) that causes a conversion
21 | overflow -> OPERR, the exponent in wbte (and fpte) is:
22 | byte 56 - (62 - exp)
23 | word 48 - (62 - exp)
24 | long 32 - (62 - exp)
25 |
26 | where exp = (true exp) - 1
27 |
28 | So, wbtemp and fptemp will contain the following on erroneously
29 | signalled operr:
30 | fpts = 1
31 | fpte = $4000 (15 bit externally)
32 | byte fptm = $ffffffff ffffff80
33 | word fptm = $ffffffff ffff8000
34 | long fptm = $ffffffff 80000000
35 |
36 | Note 2: For trap enabled 040 does the following:
37 | If the inst is move_out, then same as Note 1.
38 | If the inst is not move_out, the dest is not modified.
39 | The exceptional operand is not defined for integer overflow
40 | during a move_out.
41 |
42
43 | Copyright (C) Motorola, Inc. 1990
44 | All Rights Reserved
45 |
46 | THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
47 | The copyright notice above does not evidence any
48 | actual or intended publication of such source code.
49
50 X_OPERR: |idnt 2,1 | Motorola 040 Floating Point Software Package
51
52 |section 8
53
54 .include "fpsp.h"
55
56 |xref mem_write
57 |xref real_operr
58 |xref real_inex
59 |xref get_fline
60 |xref fpsp_done
61 |xref reg_dest
62
63 .global fpsp_operr
64 fpsp_operr:
65 |
66 link %a6,#-LOCAL_SIZE
67 fsave -(%a7)
68 moveml %d0-%d1/%a0-%a1,USER_DA(%a6)
69 fmovemx %fp0-%fp3,USER_FP0(%a6)
70 fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
71
72 |
73 | Check if this is an opclass 3 instruction.
74 | If so, fall through, else branch to operr_end
75 |
76 btstb #TFLAG,T_BYTE(%a6)
77 beqs operr_end
78
79 |
80 | If the destination size is B,W,or L, the operr must be
81 | handled here.
82 |
83 movel CMDREG1B(%a6),%d0
84 bfextu %d0{#3:#3},%d0 |0=long, 4=word, 6=byte
85 cmpib #0,%d0 |determine size; check long
86 beq operr_long
87 cmpib #4,%d0 |check word
88 beq operr_word
89 cmpib #6,%d0 |check byte
90 beq operr_byte
91
92 |
93 | The size is not B,W,or L, so the operr is handled by the
94 | kernel handler. Set the operr bits and clean up, leaving
95 | only the integer exception frame on the stack, and the
96 | fpu in the original exceptional state.
97 |
98 operr_end:
99 bsetb #operr_bit,FPSR_EXCEPT(%a6)
100 bsetb #aiop_bit,FPSR_AEXCEPT(%a6)
101
102 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
103 fmovemx USER_FP0(%a6),%fp0-%fp3
104 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
105 frestore (%a7)+
106 unlk %a6
107 bral real_operr
108
109 operr_long:
110 moveql #4,%d1 |write size to d1
111 moveb STAG(%a6),%d0 |test stag for nan
112 andib #0xe0,%d0 |clr all but tag
113 cmpib #0x60,%d0 |check for nan
114 beq operr_nan
115 cmpil #0x80000000,FPTEMP_LO(%a6) |test if ls lword is special
116 bnes chklerr |if not equal, check for incorrect operr
117 bsr check_upper |check if exp and ms mant are special
118 tstl %d0
119 bnes chklerr |if d0 is true, check for incorrect operr
120 movel #0x80000000,%d0 |store special case result
121 bsr operr_store
122 bra not_enabled |clean and exit
123 |
124 | CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
125 |
126 chklerr:
127 movew FPTEMP_EX(%a6),%d0
128 andw #0x7FFF,%d0 |ignore sign bit
129 cmpw #0x3FFE,%d0 |this is the only possible exponent value
130 bnes chklerr2
131 fixlong:
132 movel FPTEMP_LO(%a6),%d0
133 bsr operr_store
134 bra not_enabled
135 chklerr2:
136 movew FPTEMP_EX(%a6),%d0
137 andw #0x7FFF,%d0 |ignore sign bit
138 cmpw #0x4000,%d0
139 bcc store_max |exponent out of range
140
141 movel FPTEMP_LO(%a6),%d0
142 andl #0x7FFF0000,%d0 |look for all 1's on bits 30-16
143 cmpl #0x7FFF0000,%d0
144 beqs fixlong
145
146 tstl FPTEMP_LO(%a6)
147 bpls chklepos
148 cmpl #0xFFFFFFFF,FPTEMP_HI(%a6)
149 beqs fixlong
150 bra store_max
151 chklepos:
152 tstl FPTEMP_HI(%a6)
153 beqs fixlong
154 bra store_max
155
156 operr_word:
157 moveql #2,%d1 |write size to d1
158 moveb STAG(%a6),%d0 |test stag for nan
159 andib #0xe0,%d0 |clr all but tag
160 cmpib #0x60,%d0 |check for nan
161 beq operr_nan
162 cmpil #0xffff8000,FPTEMP_LO(%a6) |test if ls lword is special
163 bnes chkwerr |if not equal, check for incorrect operr
164 bsr check_upper |check if exp and ms mant are special
165 tstl %d0
166 bnes chkwerr |if d0 is true, check for incorrect operr
167 movel #0x80000000,%d0 |store special case result
168 bsr operr_store
169 bra not_enabled |clean and exit
170 |
171 | CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
172 |
173 chkwerr:
174 movew FPTEMP_EX(%a6),%d0
175 andw #0x7FFF,%d0 |ignore sign bit
176 cmpw #0x3FFE,%d0 |this is the only possible exponent value
177 bnes store_max
178 movel FPTEMP_LO(%a6),%d0
179 swap %d0
180 bsr operr_store
181 bra not_enabled
182
183 operr_byte:
184 moveql #1,%d1 |write size to d1
185 moveb STAG(%a6),%d0 |test stag for nan
186 andib #0xe0,%d0 |clr all but tag
187 cmpib #0x60,%d0 |check for nan
188 beqs operr_nan
189 cmpil #0xffffff80,FPTEMP_LO(%a6) |test if ls lword is special
190 bnes chkberr |if not equal, check for incorrect operr
191 bsr check_upper |check if exp and ms mant are special
192 tstl %d0
193 bnes chkberr |if d0 is true, check for incorrect operr
194 movel #0x80000000,%d0 |store special case result
195 bsr operr_store
196 bra not_enabled |clean and exit
197 |
198 | CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
199 |
200 chkberr:
201 movew FPTEMP_EX(%a6),%d0
202 andw #0x7FFF,%d0 |ignore sign bit
203 cmpw #0x3FFE,%d0 |this is the only possible exponent value
204 bnes store_max
205 movel FPTEMP_LO(%a6),%d0
206 asll #8,%d0
207 swap %d0
208 bsr operr_store
209 bra not_enabled
210
211 |
212 | This operr condition is not of the special case. Set operr
213 | and aiop and write the portion of the nan to memory for the
214 | given size.
215 |
216 operr_nan:
217 orl #opaop_mask,USER_FPSR(%a6) |set operr & aiop
218
219 movel ETEMP_HI(%a6),%d0 |output will be from upper 32 bits
220 bsr operr_store
221 bra end_operr
222 |
223 | Store_max loads the max pos or negative for the size, sets
224 | the operr and aiop bits, and clears inex and ainex, incorrectly
225 | set by the 040.
226 |
227 store_max:
228 orl #opaop_mask,USER_FPSR(%a6) |set operr & aiop
229 bclrb #inex2_bit,FPSR_EXCEPT(%a6)
230 bclrb #ainex_bit,FPSR_AEXCEPT(%a6)
231 fmovel #0,%FPSR
232
233 tstw FPTEMP_EX(%a6) |check sign
234 blts load_neg
235 movel #0x7fffffff,%d0
236 bsr operr_store
237 bra end_operr
238 load_neg:
239 movel #0x80000000,%d0
240 bsr operr_store
241 bra end_operr
242
243 |
244 | This routine stores the data in d0, for the given size in d1,
245 | to memory or data register as required. A read of the fline
246 | is required to determine the destination.
247 |
248 operr_store:
249 movel %d0,L_SCR1(%a6) |move write data to L_SCR1
250 movel %d1,-(%a7) |save register size
251 bsrl get_fline |fline returned in d0
252 movel (%a7)+,%d1
253 bftst %d0{#26:#3} |if mode is zero, dest is Dn
254 bnes dest_mem
255 |
256 | Destination is Dn. Get register number from d0. Data is on
257 | the stack at (a7). D1 has size: 1=byte,2=word,4=long/single
258 |
259 andil #7,%d0 |isolate register number
260 cmpil #4,%d1
261 beqs op_long |the most frequent case
262 cmpil #2,%d1
263 bnes op_con
264 orl #8,%d0
265 bras op_con
266 op_long:
267 orl #0x10,%d0
268 op_con:
269 movel %d0,%d1 |format size:reg for reg_dest
270 bral reg_dest |call to reg_dest returns to caller
271 | ;of operr_store
272 |
273 | Destination is memory. Get <ea> from integer exception frame
274 | and call mem_write.
275 |
276 dest_mem:
277 leal L_SCR1(%a6),%a0 |put ptr to write data in a0
278 movel EXC_EA(%a6),%a1 |put user destination address in a1
279 movel %d1,%d0 |put size in d0
280 bsrl mem_write
281 rts
282 |
283 | Check the exponent for $c000 and the upper 32 bits of the
284 | mantissa for $ffffffff. If both are true, return d0 clr
285 | and store the lower n bits of the least lword of FPTEMP
286 | to d0 for write out. If not, it is a real operr, and set d0.
287 |
288 check_upper:
289 cmpil #0xffffffff,FPTEMP_HI(%a6) |check if first byte is all 1's
290 bnes true_operr |if not all 1's then was true operr
291 cmpiw #0xc000,FPTEMP_EX(%a6) |check if incorrectly signalled
292 beqs not_true_operr |branch if not true operr
293 cmpiw #0xbfff,FPTEMP_EX(%a6) |check if incorrectly signalled
294 beqs not_true_operr |branch if not true operr
295 true_operr:
296 movel #1,%d0 |signal real operr
297 rts
298 not_true_operr:
299 clrl %d0 |signal no real operr
300 rts
301
302 |
303 | End_operr tests for operr enabled. If not, it cleans up the stack
304 | and does an rte. If enabled, it cleans up the stack and branches
305 | to the kernel operr handler with only the integer exception
306 | frame on the stack and the fpu in the original exceptional state
307 | with correct data written to the destination.
308 |
309 end_operr:
310 btstb #operr_bit,FPCR_ENABLE(%a6)
311 beqs not_enabled
312 enabled:
313 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
314 fmovemx USER_FP0(%a6),%fp0-%fp3
315 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
316 frestore (%a7)+
317 unlk %a6
318 bral real_operr
319
320 not_enabled:
321 |
322 | It is possible to have either inex2 or inex1 exceptions with the
323 | operr. If the inex enable bit is set in the FPCR, and either
324 | inex2 or inex1 occurred, we must clean up and branch to the
325 | real inex handler.
326 |
327 ck_inex:
328 moveb FPCR_ENABLE(%a6),%d0
329 andb FPSR_EXCEPT(%a6),%d0
330 andib #0x3,%d0
331 beq operr_exit
332 |
333 | Inexact enabled and reported, and we must take an inexact exception.
334 |
335 take_inex:
336 moveb #INEX_VEC,EXC_VEC+1(%a6)
337 movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
338 orl #sx_mask,E_BYTE(%a6)
339 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
340 fmovemx USER_FP0(%a6),%fp0-%fp3
341 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
342 frestore (%a7)+
343 unlk %a6
344 bral real_inex
345 |
346 | Since operr is only an E1 exception, there is no need to frestore
347 | any state back to the fpu.
348 |
349 operr_exit:
350 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
351 fmovemx USER_FP0(%a6),%fp0-%fp3
352 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
353 unlk %a6
354 bral fpsp_done
355
356 |end
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