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25 | THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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