1 |
2 | x_snan.sa 3.3 7/1/91
3 |
4 | fpsp_snan --- FPSP handler for signalling NAN exception
5 |
6 | SNAN for float -> integer conversions (integer conversion of
7 | an SNAN) is a non-maskable run-time exception.
8 |
9 | For trap disabled the 040 does the following:
10 | If the dest data format is s, d, or x, then the SNAN bit in the NAN
11 | is set to one and the resulting non-signaling NAN (truncated if
12 | necessary) is transferred to the dest. If the dest format is b, w,
13 | or l, then garbage is written to the dest (actually the upper 32 bits
14 | of the mantissa are sent to the integer unit).
15 |
16 | For trap enabled the 040 does the following:
17 | If the inst is move_out, then the results are the same as for trap
18 | disabled with the exception posted. If the instruction is not move_
19 | out, the dest. is not modified, and the exception is posted.
20 |
21
22 | Copyright (C) Motorola, Inc. 1990
23 | All Rights Reserved
24 |
25 | For details on the license for this file, please see the
26 | file, README, in this same directory.
27
28 X_SNAN: |idnt 2,1 | Motorola 040 Floating Point Software Package
29
30 |section 8
31
32 #include "fpsp.h"
33
34 |xref get_fline
35 |xref mem_write
36 |xref real_snan
37 |xref real_inex
38 |xref fpsp_done
39 |xref reg_dest
40
41 .global fpsp_snan
42 fpsp_snan:
43 link %a6,#-LOCAL_SIZE
44 fsave -(%a7)
45 moveml %d0-%d1/%a0-%a1,USER_DA(%a6)
46 fmovemx %fp0-%fp3,USER_FP0(%a6)
47 fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
48
49 |
50 | Check if trap enabled
51 |
52 btstb #snan_bit,FPCR_ENABLE(%a6)
53 bnes ena |If enabled, then branch
54
55 bsrl move_out |else SNAN disabled
56 |
57 | It is possible to have an inex1 exception with the
58 | snan. If the inex enable bit is set in the FPCR, and either
59 | inex2 or inex1 occurred, we must clean up and branch to the
60 | real inex handler.
61 |
62 ck_inex:
63 moveb FPCR_ENABLE(%a6),%d0
64 andb FPSR_EXCEPT(%a6),%d0
65 andib #0x3,%d0
66 beq end_snan
67 |
68 | Inexact enabled and reported, and we must take an inexact exception.
69 |
70 take_inex:
71 moveb #INEX_VEC,EXC_VEC+1(%a6)
72 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
73 fmovemx USER_FP0(%a6),%fp0-%fp3
74 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
75 frestore (%a7)+
76 unlk %a6
77 bral real_inex
78 |
79 | SNAN is enabled. Check if inst is move_out.
80 | Make any corrections to the 040 output as necessary.
81 |
82 ena:
83 btstb #5,CMDREG1B(%a6) |if set, inst is move out
84 beq not_out
85
86 bsrl move_out
87
88 report_snan:
89 moveb (%a7),VER_TMP(%a6)
90 cmpib #VER_40,(%a7) |test for orig unimp frame
91 bnes ck_rev
92 moveql #13,%d0 |need to zero 14 lwords
93 bras rep_con
94 ck_rev:
95 moveql #11,%d0 |need to zero 12 lwords
96 rep_con:
97 clrl (%a7)
98 loop1:
99 clrl -(%a7) |clear and dec a7
100 dbra %d0,loop1
101 moveb VER_TMP(%a6),(%a7) |format a busy frame
102 moveb #BUSY_SIZE-4,1(%a7)
103 movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
104 orl #sx_mask,E_BYTE(%a6)
105 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
106 fmovemx USER_FP0(%a6),%fp0-%fp3
107 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
108 frestore (%a7)+
109 unlk %a6
110 bral real_snan
111 |
112 | Exit snan handler by expanding the unimp frame into a busy frame
113 |
114 end_snan:
115 bclrb #E1,E_BYTE(%a6)
116
117 moveb (%a7),VER_TMP(%a6)
118 cmpib #VER_40,(%a7) |test for orig unimp frame
119 bnes ck_rev2
120 moveql #13,%d0 |need to zero 14 lwords
121 bras rep_con2
122 ck_rev2:
123 moveql #11,%d0 |need to zero 12 lwords
124 rep_con2:
125 clrl (%a7)
126 loop2:
127 clrl -(%a7) |clear and dec a7
128 dbra %d0,loop2
129 moveb VER_TMP(%a6),(%a7) |format a busy frame
130 moveb #BUSY_SIZE-4,1(%a7) |write busy size
131 movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
132 orl #sx_mask,E_BYTE(%a6)
133 moveml USER_DA(%a6),%d0-%d1/%a0-%a1
134 fmovemx USER_FP0(%a6),%fp0-%fp3
135 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
136 frestore (%a7)+
137 unlk %a6
138 bral fpsp_done
139
140 |
141 | Move_out
142 |
143 move_out:
144 movel EXC_EA(%a6),%a0 |get <ea> from exc frame
145
146 bfextu CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
147 cmpil #0,%d0 |check for long
148 beqs sto_long |branch if move_out long
149
150 cmpil #4,%d0 |check for word
151 beqs sto_word |branch if move_out word
152
153 cmpil #6,%d0 |check for byte
154 beqs sto_byte |branch if move_out byte
155
156 |
157 | Not byte, word or long
158 |
159 rts
160 |
161 | Get the 32 most significant bits of etemp mantissa
162 |
163 sto_long:
164 movel ETEMP_HI(%a6),%d1
165 movel #4,%d0 |load byte count
166 |
167 | Set signalling nan bit
168 |
169 bsetl #30,%d1
170 |
171 | Store to the users destination address
172 |
173 tstl %a0 |check if <ea> is 0
174 beqs wrt_dn |destination is a data register
175
176 movel %d1,-(%a7) |move the snan onto the stack
177 movel %a0,%a1 |load dest addr into a1
178 movel %a7,%a0 |load src addr of snan into a0
179 bsrl mem_write |write snan to user memory
180 movel (%a7)+,%d1 |clear off stack
181 rts
182 |
183 | Get the 16 most significant bits of etemp mantissa
184 |
185 sto_word:
186 movel ETEMP_HI(%a6),%d1
187 movel #2,%d0 |load byte count
188 |
189 | Set signalling nan bit
190 |
191 bsetl #30,%d1
192 |
193 | Store to the users destination address
194 |
195 tstl %a0 |check if <ea> is 0
196 beqs wrt_dn |destination is a data register
197
198 movel %d1,-(%a7) |move the snan onto the stack
199 movel %a0,%a1 |load dest addr into a1
200 movel %a7,%a0 |point to low word
201 bsrl mem_write |write snan to user memory
202 movel (%a7)+,%d1 |clear off stack
203 rts
204 |
205 | Get the 8 most significant bits of etemp mantissa
206 |
207 sto_byte:
208 movel ETEMP_HI(%a6),%d1
209 movel #1,%d0 |load byte count
210 |
211 | Set signalling nan bit
212 |
213 bsetl #30,%d1
214 |
215 | Store to the users destination address
216 |
217 tstl %a0 |check if <ea> is 0
218 beqs wrt_dn |destination is a data register
219 movel %d1,-(%a7) |move the snan onto the stack
220 movel %a0,%a1 |load dest addr into a1
221 movel %a7,%a0 |point to source byte
222 bsrl mem_write |write snan to user memory
223 movel (%a7)+,%d1 |clear off stack
224 rts
225
226 |
227 | wrt_dn --- write to a data register
228 |
229 | We get here with D1 containing the data to write and D0 the
230 | number of bytes to write: 1=byte,2=word,4=long.
231 |
232 wrt_dn:
233 movel %d1,L_SCR1(%a6) |data
234 movel %d0,-(%a7) |size
235 bsrl get_fline |returns fline word in d0
236 movel %d0,%d1
237 andil #0x7,%d1 |d1 now holds register number
238 movel (%sp)+,%d0 |get original size
239 cmpil #4,%d0
240 beqs wrt_long
241 cmpil #2,%d0
242 bnes wrt_byte
243 wrt_word:
244 orl #0x8,%d1
245 bral reg_dest
246 wrt_long:
247 orl #0x10,%d1
248 bral reg_dest
249 wrt_byte:
250 bral reg_dest
251 |
252 | Check if it is a src nan or dst nan
253 |
254 not_out:
255 movel DTAG(%a6),%d0
256 bfextu %d0{#0:#3},%d0 |isolate dtag in lsbs
257
258 cmpib #3,%d0 |check for nan in destination
259 bnes issrc |destination nan has priority
260 dst_nan:
261 btstb #6,FPTEMP_HI(%a6) |check if dest nan is an snan
262 bnes issrc |no, so check source for snan
263 movew FPTEMP_EX(%a6),%d0
264 bras cont
265 issrc:
266 movew ETEMP_EX(%a6),%d0
267 cont:
268 btstl #15,%d0 |test for sign of snan
269 beqs clr_neg
270 bsetb #neg_bit,FPSR_CC(%a6)
271 bra report_snan
272 clr_neg:
273 bclrb #neg_bit,FPSR_CC(%a6)
274 bra report_snan
275
276 |end