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