1 |
2 | x_unfl.sa 3.4 7/1/91
3 |
4 | fpsp_unfl --- FPSP handler for underfl
5 |
6 | Trap disabled results
7 | For 881/2 compatibility, sw must denor
8 | result, then store the result. Denormalizat
9 | by taking the intermediate result (which is
10 | shifting the mantissa right while incrementi
11 | it is equal to the denormalized exponent for
12 | format. After denormalization, the result i
13 | destination format.
14 |
15 | Trap enabled results
16 | All trap disabled code applies. In add
17 | operand needs to made available to the user
18 | added to the exponent.
19 |
20
21 | Copyright (C) Motorola, Inc. 1
22 | All Rights Reserved
23 |
24 | For details on the license for this fi
25 | file, README, in this same directory.
26
27 X_UNFL: |idnt 2,1 | Motorola 040 Floating P
28
29 |section 8
30
31 #include "fpsp.h"
32
33 |xref denorm
34 |xref round
35 |xref store
36 |xref g_rndpr
37 |xref g_opcls
38 |xref g_dfmtou
39 |xref real_unfl
40 |xref real_inex
41 |xref fpsp_done
42 |xref b1238_fix
43
44 .global fpsp_unfl
45 fpsp_unfl:
46 link %a6,#-LOCAL_SIZE
47 fsave -(%a7)
48 moveml %d0-%d1/%a0-%a1,USER_D
49 fmovemx %fp0-%fp3,USER_FP0(%a6)
50 fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%
51
52 |
53 bsrl unf_res |denormalize,
54 |
55 | If underflow exceptions are not enabled, che
56 | exception
57 |
58 btstb #unfl_bit,FPCR_ENABLE(
59 beqs ck_inex
60
61 btstb #E3,E_BYTE(%a6)
62 beqs no_e3_1
63 |
64 | Clear dirty bit on dest resister in the fram
65 | to b1238_fix.
66 |
67 bfextu CMDREG3B(%a6){#6:#3},%
68 bclrb %d0,FPR_DIRTY_BITS(%a6
69 bsrl b1238_fix
70 movel USER_FPSR(%a6),FPSR_SH
71 orl #sx_mask,E_BYTE(%a6)
72 no_e3_1:
73 moveml USER_DA(%a6),%d0-%d1/%
74 fmovemx USER_FP0(%a6),%fp0-%fp3
75 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fp
76 frestore (%a7)+
77 unlk %a6
78 bral real_unfl
79 |
80 | It is possible to have either inex2 or inex1
81 | unfl. If the inex enable bit is set in the
82 | inex2 or inex1 occurred, we must clean up an
83 | real inex handler.
84 |
85 ck_inex:
86 moveb FPCR_ENABLE(%a6),%d0
87 andb FPSR_EXCEPT(%a6),%d0
88 andib #0x3,%d0
89 beqs unfl_done
90
91 |
92 | Inexact enabled and reported, and we must ta
93 |
94 take_inex:
95 btstb #E3,E_BYTE(%a6)
96 beqs no_e3_2
97 |
98 | Clear dirty bit on dest resister in the fram
99 | to b1238_fix.
100 |
101 bfextu CMDREG3B(%a6){#6:#3},%
102 bclrb %d0,FPR_DIRTY_BITS(%a6
103 bsrl b1238_fix
104 movel USER_FPSR(%a6),FPSR_SH
105 orl #sx_mask,E_BYTE(%a6)
106 no_e3_2:
107 moveb #INEX_VEC,EXC_VEC+1(%a
108 moveml USER_DA(%a6),%d0-%d1/%a
109 fmovemx USER_FP0(%a6),%fp0-%fp3
110 fmoveml USER_FPCR(%a6),%fpcr/%f
111 frestore (%a7)+
112 unlk %a6
113 bral real_inex
114
115 unfl_done:
116 bclrb #E3,E_BYTE(%a6)
117 beqs e1_set |if se
118 |
119 | Clear dirty bit on dest resister in the fram
120 | to b1238_fix.
121 |
122 bfextu CMDREG3B(%a6){#6:#3},%
123 bclrb %d0,FPR_DIRTY_BITS(%a6
124 bsrl b1238_fix
125 movel USER_FPSR(%a6),FPSR_SH
126 orl #sx_mask,E_BYTE(%a6)
127 moveml USER_DA(%a6),%d0-%d1/%
128 fmovemx USER_FP0(%a6),%fp0-%fp3
129 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fp
130 frestore (%a7)+
131 unlk %a6
132 bral fpsp_done
133 e1_set:
134 moveml USER_DA(%a6),%d0-%d1/%
135 fmovemx USER_FP0(%a6),%fp0-%fp3
136 fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fp
137 unlk %a6
138 bral fpsp_done
139 |
140 | unf_res --- underflow result calculati
141 |
142 unf_res:
143 bsrl g_rndpr |retur
144 | ;1=sgl
145 | ;we ne
146 | ;upper
147 movew #0,-(%a7)
148 movew %d0,-(%a7) |copy
149 |
150 |
151 | If the exception bit set is E3, the exceptio
152 | fpu is in WBTEMP; else it is in FPTEMP.
153 |
154 btstb #E3,E_BYTE(%a6)
155 beqs unf_E1
156 unf_E3:
157 lea WBTEMP(%a6),%a0 |a0 no
158 |
159 | Test for fsgldiv and fsglmul. If the inst w
160 | force the precision to extended for the deno
161 | the user's precision for the round routine.
162 |
163 movew CMDREG3B(%a6),%d1
164 andiw #0x7f,%d1
165 cmpiw #0x30,%d1
166 beqs unf_sgl
167 cmpiw #0x33,%d1
168 bnes unf_cont |if no
169 unf_sgl:
170 clrl %d0
171 movew #0x1,(%a7) |overr
172 | ;force
173 bras unf_cont
174 unf_E1:
175 lea FPTEMP(%a6),%a0 |a0 no
176 unf_cont:
177 bclrb #sign_bit,LOCAL_EX(%a0
178 sne LOCAL_SGN(%a0)
179
180 bsrl denorm |retur
181 |
182 | WARNING:
183 | ;d0 has guard,
184 | ;make sure tha
185 | ;before it rea
186 | ;also ensure t
187
188 |
189 | Set up d1 for round subroutine d1 contains t
190 | information respectively on upper/lower regi
191 |
192 bfextu FPCR_MODE(%a6){#2:#2},
193 |
194 addl (%a7)+,%d1
195 |
196 | WARNING: a0 and d0 are assumed to be intact
197 | round subroutines. All code between these tw
198 | must not corrupt a0 and d0.
199 |
200 |
201 | Perform Round
202 | Input: a0 points to input ope
203 | d0{31:29} has guard, r
204 | d1{01:00} has rounding
205 | d1{17:16} has rounding
206 | Output: a0 points to rounded o
207 |
208
209 bsrl round |retur
210 |
211 | Differentiate between store to memory vs. st
212 |
213 unf_store:
214 bsrl g_opcls |retur
215 cmpib #0x3,%d0
216 bnes not_opc011
217 |
218 | At this point, a store to memory is pending
219 |
220 opc011:
221 bsrl g_dfmtou
222 tstb %d0
223 beqs ext_opc011 |If ex
224 | ;If destinatio
225 tstb LOCAL_HI(%a0) |If ro
226 | ;subtr
227 bmis ext_opc011
228 subqw #1,LOCAL_EX(%a0)
229 | ;normalized bi
230 | ; nor
231 | ;single
232 | ;double
233 |
234 ext_opc011:
235 bsrl store |store
236 bras unf_done |finis
237
238 |
239 | At this point, a store to a float register i
240 |
241 not_opc011:
242 bsrl store |stores to flo
243 | ;a0 is not cor
244 | ;float registe
245 |
246 | Set the condition codes according to result
247 |
248 tstl LOCAL_HI(%a0) |check
249 bnes ck_sgn
250 tstl LOCAL_LO(%a0) |check
251 bnes ck_sgn
252 bsetb #z_bit,FPSR_CC(%a6) |s
253 ck_sgn:
254 btstb #sign_bit,LOCAL_EX(%a0
255 beqs unf_done
256 bsetb #neg_bit,FPSR_CC(%a6)
257
258 |
259 | Finish.
260 |
261 unf_done:
262 btstb #inex2_bit,FPSR_EXCEPT
263 beqs no_aunfl
264 bsetb #aunfl_bit,FPSR_AEXCEP
265 no_aunfl:
266 rts
267
268 |end
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.