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1|
2| scale.sa 3.3 7/30/91
3|
4| The entry point sSCALE computes the destination operand
5| scaled by the source operand. If the absolute value of
6| the source operand is (>= 2^14) an overflow or underflow
7| is returned.
8|
9| The entry point sscale is called from do_func to emulate
10| the fscale unimplemented instruction.
11|
12| Input: Double-extended destination operand in FPTEMP,
13| double-extended source operand in ETEMP.
14|
15| Output: The function returns scale(X,Y) to fp0.
16|
17| Modifies: fp0.
18|
19| Algorithm:
20|
21| Copyright (C) Motorola, Inc. 1990
22| All Rights Reserved
23|
24| For details on the license for this file, please see the
25| file, README, in this same directory.
26
27|SCALE idnt 2,1 | Motorola 040 Floating Point Software Package
28
29 |section 8
30
31#include "fpsp.h"
32
33 |xref t_ovfl2
34 |xref t_unfl
35 |xref round
36 |xref t_resdnrm
37
38SRC_BNDS: .short 0x3fff,0x400c
39
40|
41| This entry point is used by the unimplemented instruction exception
42| handler.
43|
44|
45|
46| FSCALE
47|
48 .global sscale
49sscale:
50 fmovel #0,%fpcr |clr user enabled exc
51 clrl %d1
52 movew FPTEMP(%a6),%d1 |get dest exponent
53 smi L_SCR1(%a6) |use L_SCR1 to hold sign
54 andil #0x7fff,%d1 |strip sign
55 movew ETEMP(%a6),%d0 |check src bounds
56 andiw #0x7fff,%d0 |clr sign bit
57 cmp2w SRC_BNDS,%d0
58 bccs src_in
59 cmpiw #0x400c,%d0 |test for too large
60 bge src_out
61|
62| The source input is below 1, so we check for denormalized numbers
63| and set unfl.
64|
65src_small:
66 moveb DTAG(%a6),%d0
67 andib #0xe0,%d0
68 tstb %d0
69 beqs no_denorm
70 st STORE_FLG(%a6) |dest already contains result
71 orl #unfl_mask,USER_FPSR(%a6) |set UNFL
72den_done:
73 leal FPTEMP(%a6),%a0
74 bra t_resdnrm
75no_denorm:
76 fmovel USER_FPCR(%a6),%FPCR
77 fmovex FPTEMP(%a6),%fp0 |simply return dest
78 rts
79
80
81|
82| Source is within 2^14 range. To perform the int operation,
83| move it to d0.
84|
85src_in:
86 fmovex ETEMP(%a6),%fp0 |move in src for int
87 fmovel #rz_mode,%fpcr |force rz for src conversion
88 fmovel %fp0,%d0 |int src to d0
89 fmovel #0,%FPSR |clr status from above
90 tstw ETEMP(%a6) |check src sign
91 blt src_neg
92|
93| Source is positive. Add the src to the dest exponent.
94| The result can be denormalized, if src = 0, or overflow,
95| if the result of the add sets a bit in the upper word.
96|
97src_pos:
98 tstw %d1 |check for denorm
99 beq dst_dnrm
100 addl %d0,%d1 |add src to dest exp
101 beqs denorm |if zero, result is denorm
102 cmpil #0x7fff,%d1 |test for overflow
103 bges ovfl
104 tstb L_SCR1(%a6)
105 beqs spos_pos
106 orw #0x8000,%d1
107spos_pos:
108 movew %d1,FPTEMP(%a6) |result in FPTEMP
109 fmovel USER_FPCR(%a6),%FPCR
110 fmovex FPTEMP(%a6),%fp0 |write result to fp0
111 rts
112ovfl:
113 tstb L_SCR1(%a6)
114 beqs sovl_pos
115 orw #0x8000,%d1
116sovl_pos:
117 movew FPTEMP(%a6),ETEMP(%a6) |result in ETEMP
118 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
119 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
120 bra t_ovfl2
121
122denorm:
123 tstb L_SCR1(%a6)
124 beqs den_pos
125 orw #0x8000,%d1
126den_pos:
127 tstl FPTEMP_HI(%a6) |check j bit
128 blts nden_exit |if set, not denorm
129 movew %d1,ETEMP(%a6) |input expected in ETEMP
130 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
131 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
132 orl #unfl_bit,USER_FPSR(%a6) |set unfl
133 leal ETEMP(%a6),%a0
134 bra t_resdnrm
135nden_exit:
136 movew %d1,FPTEMP(%a6) |result in FPTEMP
137 fmovel USER_FPCR(%a6),%FPCR
138 fmovex FPTEMP(%a6),%fp0 |write result to fp0
139 rts
140
141|
142| Source is negative. Add the src to the dest exponent.
143| (The result exponent will be reduced). The result can be
144| denormalized.
145|
146src_neg:
147 addl %d0,%d1 |add src to dest
148 beqs denorm |if zero, result is denorm
149 blts fix_dnrm |if negative, result is
150| ;needing denormalization
151 tstb L_SCR1(%a6)
152 beqs sneg_pos
153 orw #0x8000,%d1
154sneg_pos:
155 movew %d1,FPTEMP(%a6) |result in FPTEMP
156 fmovel USER_FPCR(%a6),%FPCR
157 fmovex FPTEMP(%a6),%fp0 |write result to fp0
158 rts
159
160
161|
162| The result exponent is below denorm value. Test for catastrophic
163| underflow and force zero if true. If not, try to shift the
164| mantissa right until a zero exponent exists.
165|
166fix_dnrm:
167 cmpiw #0xffc0,%d1 |lower bound for normalization
168 blt fix_unfl |if lower, catastrophic unfl
169 movew %d1,%d0 |use d0 for exp
170 movel %d2,-(%a7) |free d2 for norm
171 movel FPTEMP_HI(%a6),%d1
172 movel FPTEMP_LO(%a6),%d2
173 clrl L_SCR2(%a6)
174fix_loop:
175 addw #1,%d0 |drive d0 to 0
176 lsrl #1,%d1 |while shifting the
177 roxrl #1,%d2 |mantissa to the right
178 bccs no_carry
179 st L_SCR2(%a6) |use L_SCR2 to capture inex
180no_carry:
181 tstw %d0 |it is finished when
182 blts fix_loop |d0 is zero or the mantissa
183 tstb L_SCR2(%a6)
184 beqs tst_zero
185 orl #unfl_inx_mask,USER_FPSR(%a6)
186| ;set unfl, aunfl, ainex
187|
188| Test for zero. If zero, simply use fmove to return +/- zero
189| to the fpu.
190|
191tst_zero:
192 clrw FPTEMP_EX(%a6)
193 tstb L_SCR1(%a6) |test for sign
194 beqs tst_con
195 orw #0x8000,FPTEMP_EX(%a6) |set sign bit
196tst_con:
197 movel %d1,FPTEMP_HI(%a6)
198 movel %d2,FPTEMP_LO(%a6)
199 movel (%a7)+,%d2
200 tstl %d1
201 bnes not_zero
202 tstl FPTEMP_LO(%a6)
203 bnes not_zero
204|
205| Result is zero. Check for rounding mode to set lsb. If the
206| mode is rp, and the zero is positive, return smallest denorm.
207| If the mode is rm, and the zero is negative, return smallest
208| negative denorm.
209|
210 btstb #5,FPCR_MODE(%a6) |test if rm or rp
211 beqs no_dir
212 btstb #4,FPCR_MODE(%a6) |check which one
213 beqs zer_rm
214zer_rp:
215 tstb L_SCR1(%a6) |check sign
216 bnes no_dir |if set, neg op, no inc
217 movel #1,FPTEMP_LO(%a6) |set lsb
218 bras sm_dnrm
219zer_rm:
220 tstb L_SCR1(%a6) |check sign
221 beqs no_dir |if clr, neg op, no inc
222 movel #1,FPTEMP_LO(%a6) |set lsb
223 orl #neg_mask,USER_FPSR(%a6) |set N
224 bras sm_dnrm
225no_dir:
226 fmovel USER_FPCR(%a6),%FPCR
227 fmovex FPTEMP(%a6),%fp0 |use fmove to set cc's
228 rts
229
230|
231| The rounding mode changed the zero to a smallest denorm. Call
232| t_resdnrm with exceptional operand in ETEMP.
233|
234sm_dnrm:
235 movel FPTEMP_EX(%a6),ETEMP_EX(%a6)
236 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
237 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
238 leal ETEMP(%a6),%a0
239 bra t_resdnrm
240
241|
242| Result is still denormalized.
243|
244not_zero:
245 orl #unfl_mask,USER_FPSR(%a6) |set unfl
246 tstb L_SCR1(%a6) |check for sign
247 beqs fix_exit
248 orl #neg_mask,USER_FPSR(%a6) |set N
249fix_exit:
250 bras sm_dnrm
251
252
253|
254| The result has underflowed to zero. Return zero and set
255| unfl, aunfl, and ainex.
256|
257fix_unfl:
258 orl #unfl_inx_mask,USER_FPSR(%a6)
259 btstb #5,FPCR_MODE(%a6) |test if rm or rp
260 beqs no_dir2
261 btstb #4,FPCR_MODE(%a6) |check which one
262 beqs zer_rm2
263zer_rp2:
264 tstb L_SCR1(%a6) |check sign
265 bnes no_dir2 |if set, neg op, no inc
266 clrl FPTEMP_EX(%a6)
267 clrl FPTEMP_HI(%a6)
268 movel #1,FPTEMP_LO(%a6) |set lsb
269 bras sm_dnrm |return smallest denorm
270zer_rm2:
271 tstb L_SCR1(%a6) |check sign
272 beqs no_dir2 |if clr, neg op, no inc
273 movew #0x8000,FPTEMP_EX(%a6)
274 clrl FPTEMP_HI(%a6)
275 movel #1,FPTEMP_LO(%a6) |set lsb
276 orl #neg_mask,USER_FPSR(%a6) |set N
277 bra sm_dnrm |return smallest denorm
278
279no_dir2:
280 tstb L_SCR1(%a6)
281 bges pos_zero
282neg_zero:
283 clrl FP_SCR1(%a6) |clear the exceptional operand
284 clrl FP_SCR1+4(%a6) |for gen_except.
285 clrl FP_SCR1+8(%a6)
286 fmoves #0x80000000,%fp0
287 rts
288pos_zero:
289 clrl FP_SCR1(%a6) |clear the exceptional operand
290 clrl FP_SCR1+4(%a6) |for gen_except.
291 clrl FP_SCR1+8(%a6)
292 fmoves #0x00000000,%fp0
293 rts
294
295|
296| The destination is a denormalized number. It must be handled
297| by first shifting the bits in the mantissa until it is normalized,
298| then adding the remainder of the source to the exponent.
299|
300dst_dnrm:
301 moveml %d2/%d3,-(%a7)
302 movew FPTEMP_EX(%a6),%d1
303 movel FPTEMP_HI(%a6),%d2
304 movel FPTEMP_LO(%a6),%d3
305dst_loop:
306 tstl %d2 |test for normalized result
307 blts dst_norm |exit loop if so
308 tstl %d0 |otherwise, test shift count
309 beqs dst_fin |if zero, shifting is done
310 subil #1,%d0 |dec src
311 lsll #1,%d3
312 roxll #1,%d2
313 bras dst_loop
314|
315| Destination became normalized. Simply add the remaining
316| portion of the src to the exponent.
317|
318dst_norm:
319 addw %d0,%d1 |dst is normalized; add src
320 tstb L_SCR1(%a6)
321 beqs dnrm_pos
322 orl #0x8000,%d1
323dnrm_pos:
324 movemw %d1,FPTEMP_EX(%a6)
325 moveml %d2,FPTEMP_HI(%a6)
326 moveml %d3,FPTEMP_LO(%a6)
327 fmovel USER_FPCR(%a6),%FPCR
328 fmovex FPTEMP(%a6),%fp0
329 moveml (%a7)+,%d2/%d3
330 rts
331
332|
333| Destination remained denormalized. Call t_excdnrm with
334| exceptional operand in ETEMP.
335|
336dst_fin:
337 tstb L_SCR1(%a6) |check for sign
338 beqs dst_exit
339 orl #neg_mask,USER_FPSR(%a6) |set N
340 orl #0x8000,%d1
341dst_exit:
342 movemw %d1,ETEMP_EX(%a6)
343 moveml %d2,ETEMP_HI(%a6)
344 moveml %d3,ETEMP_LO(%a6)
345 orl #unfl_mask,USER_FPSR(%a6) |set unfl
346 moveml (%a7)+,%d2/%d3
347 leal ETEMP(%a6),%a0
348 bra t_resdnrm
349
350|
351| Source is outside of 2^14 range. Test the sign and branch
352| to the appropriate exception handler.
353|
354src_out:
355 tstb L_SCR1(%a6)
356 beqs scro_pos
357 orl #0x8000,%d1
358scro_pos:
359 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
360 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
361 tstw ETEMP(%a6)
362 blts res_neg
363res_pos:
364 movew %d1,ETEMP(%a6) |result in ETEMP
365 bra t_ovfl2
366res_neg:
367 movew %d1,ETEMP(%a6) |result in ETEMP
368 leal ETEMP(%a6),%a0
369 bra t_unfl
370 |end
1|
2| scale.sa 3.3 7/30/91
3|
4| The entry point sSCALE computes the destination operand
5| scaled by the source operand. If the absolute value of
6| the source operand is (>= 2^14) an overflow or underflow
7| is returned.
8|
9| The entry point sscale is called from do_func to emulate
10| the fscale unimplemented instruction.
11|
12| Input: Double-extended destination operand in FPTEMP,
13| double-extended source operand in ETEMP.
14|
15| Output: The function returns scale(X,Y) to fp0.
16|
17| Modifies: fp0.
18|
19| Algorithm:
20|
21| Copyright (C) Motorola, Inc. 1990
22| All Rights Reserved
23|
24| For details on the license for this file, please see the
25| file, README, in this same directory.
26
27|SCALE idnt 2,1 | Motorola 040 Floating Point Software Package
28
29 |section 8
30
31#include "fpsp.h"
32
33 |xref t_ovfl2
34 |xref t_unfl
35 |xref round
36 |xref t_resdnrm
37
38SRC_BNDS: .short 0x3fff,0x400c
39
40|
41| This entry point is used by the unimplemented instruction exception
42| handler.
43|
44|
45|
46| FSCALE
47|
48 .global sscale
49sscale:
50 fmovel #0,%fpcr |clr user enabled exc
51 clrl %d1
52 movew FPTEMP(%a6),%d1 |get dest exponent
53 smi L_SCR1(%a6) |use L_SCR1 to hold sign
54 andil #0x7fff,%d1 |strip sign
55 movew ETEMP(%a6),%d0 |check src bounds
56 andiw #0x7fff,%d0 |clr sign bit
57 cmp2w SRC_BNDS,%d0
58 bccs src_in
59 cmpiw #0x400c,%d0 |test for too large
60 bge src_out
61|
62| The source input is below 1, so we check for denormalized numbers
63| and set unfl.
64|
65src_small:
66 moveb DTAG(%a6),%d0
67 andib #0xe0,%d0
68 tstb %d0
69 beqs no_denorm
70 st STORE_FLG(%a6) |dest already contains result
71 orl #unfl_mask,USER_FPSR(%a6) |set UNFL
72den_done:
73 leal FPTEMP(%a6),%a0
74 bra t_resdnrm
75no_denorm:
76 fmovel USER_FPCR(%a6),%FPCR
77 fmovex FPTEMP(%a6),%fp0 |simply return dest
78 rts
79
80
81|
82| Source is within 2^14 range. To perform the int operation,
83| move it to d0.
84|
85src_in:
86 fmovex ETEMP(%a6),%fp0 |move in src for int
87 fmovel #rz_mode,%fpcr |force rz for src conversion
88 fmovel %fp0,%d0 |int src to d0
89 fmovel #0,%FPSR |clr status from above
90 tstw ETEMP(%a6) |check src sign
91 blt src_neg
92|
93| Source is positive. Add the src to the dest exponent.
94| The result can be denormalized, if src = 0, or overflow,
95| if the result of the add sets a bit in the upper word.
96|
97src_pos:
98 tstw %d1 |check for denorm
99 beq dst_dnrm
100 addl %d0,%d1 |add src to dest exp
101 beqs denorm |if zero, result is denorm
102 cmpil #0x7fff,%d1 |test for overflow
103 bges ovfl
104 tstb L_SCR1(%a6)
105 beqs spos_pos
106 orw #0x8000,%d1
107spos_pos:
108 movew %d1,FPTEMP(%a6) |result in FPTEMP
109 fmovel USER_FPCR(%a6),%FPCR
110 fmovex FPTEMP(%a6),%fp0 |write result to fp0
111 rts
112ovfl:
113 tstb L_SCR1(%a6)
114 beqs sovl_pos
115 orw #0x8000,%d1
116sovl_pos:
117 movew FPTEMP(%a6),ETEMP(%a6) |result in ETEMP
118 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
119 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
120 bra t_ovfl2
121
122denorm:
123 tstb L_SCR1(%a6)
124 beqs den_pos
125 orw #0x8000,%d1
126den_pos:
127 tstl FPTEMP_HI(%a6) |check j bit
128 blts nden_exit |if set, not denorm
129 movew %d1,ETEMP(%a6) |input expected in ETEMP
130 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
131 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
132 orl #unfl_bit,USER_FPSR(%a6) |set unfl
133 leal ETEMP(%a6),%a0
134 bra t_resdnrm
135nden_exit:
136 movew %d1,FPTEMP(%a6) |result in FPTEMP
137 fmovel USER_FPCR(%a6),%FPCR
138 fmovex FPTEMP(%a6),%fp0 |write result to fp0
139 rts
140
141|
142| Source is negative. Add the src to the dest exponent.
143| (The result exponent will be reduced). The result can be
144| denormalized.
145|
146src_neg:
147 addl %d0,%d1 |add src to dest
148 beqs denorm |if zero, result is denorm
149 blts fix_dnrm |if negative, result is
150| ;needing denormalization
151 tstb L_SCR1(%a6)
152 beqs sneg_pos
153 orw #0x8000,%d1
154sneg_pos:
155 movew %d1,FPTEMP(%a6) |result in FPTEMP
156 fmovel USER_FPCR(%a6),%FPCR
157 fmovex FPTEMP(%a6),%fp0 |write result to fp0
158 rts
159
160
161|
162| The result exponent is below denorm value. Test for catastrophic
163| underflow and force zero if true. If not, try to shift the
164| mantissa right until a zero exponent exists.
165|
166fix_dnrm:
167 cmpiw #0xffc0,%d1 |lower bound for normalization
168 blt fix_unfl |if lower, catastrophic unfl
169 movew %d1,%d0 |use d0 for exp
170 movel %d2,-(%a7) |free d2 for norm
171 movel FPTEMP_HI(%a6),%d1
172 movel FPTEMP_LO(%a6),%d2
173 clrl L_SCR2(%a6)
174fix_loop:
175 addw #1,%d0 |drive d0 to 0
176 lsrl #1,%d1 |while shifting the
177 roxrl #1,%d2 |mantissa to the right
178 bccs no_carry
179 st L_SCR2(%a6) |use L_SCR2 to capture inex
180no_carry:
181 tstw %d0 |it is finished when
182 blts fix_loop |d0 is zero or the mantissa
183 tstb L_SCR2(%a6)
184 beqs tst_zero
185 orl #unfl_inx_mask,USER_FPSR(%a6)
186| ;set unfl, aunfl, ainex
187|
188| Test for zero. If zero, simply use fmove to return +/- zero
189| to the fpu.
190|
191tst_zero:
192 clrw FPTEMP_EX(%a6)
193 tstb L_SCR1(%a6) |test for sign
194 beqs tst_con
195 orw #0x8000,FPTEMP_EX(%a6) |set sign bit
196tst_con:
197 movel %d1,FPTEMP_HI(%a6)
198 movel %d2,FPTEMP_LO(%a6)
199 movel (%a7)+,%d2
200 tstl %d1
201 bnes not_zero
202 tstl FPTEMP_LO(%a6)
203 bnes not_zero
204|
205| Result is zero. Check for rounding mode to set lsb. If the
206| mode is rp, and the zero is positive, return smallest denorm.
207| If the mode is rm, and the zero is negative, return smallest
208| negative denorm.
209|
210 btstb #5,FPCR_MODE(%a6) |test if rm or rp
211 beqs no_dir
212 btstb #4,FPCR_MODE(%a6) |check which one
213 beqs zer_rm
214zer_rp:
215 tstb L_SCR1(%a6) |check sign
216 bnes no_dir |if set, neg op, no inc
217 movel #1,FPTEMP_LO(%a6) |set lsb
218 bras sm_dnrm
219zer_rm:
220 tstb L_SCR1(%a6) |check sign
221 beqs no_dir |if clr, neg op, no inc
222 movel #1,FPTEMP_LO(%a6) |set lsb
223 orl #neg_mask,USER_FPSR(%a6) |set N
224 bras sm_dnrm
225no_dir:
226 fmovel USER_FPCR(%a6),%FPCR
227 fmovex FPTEMP(%a6),%fp0 |use fmove to set cc's
228 rts
229
230|
231| The rounding mode changed the zero to a smallest denorm. Call
232| t_resdnrm with exceptional operand in ETEMP.
233|
234sm_dnrm:
235 movel FPTEMP_EX(%a6),ETEMP_EX(%a6)
236 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
237 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
238 leal ETEMP(%a6),%a0
239 bra t_resdnrm
240
241|
242| Result is still denormalized.
243|
244not_zero:
245 orl #unfl_mask,USER_FPSR(%a6) |set unfl
246 tstb L_SCR1(%a6) |check for sign
247 beqs fix_exit
248 orl #neg_mask,USER_FPSR(%a6) |set N
249fix_exit:
250 bras sm_dnrm
251
252
253|
254| The result has underflowed to zero. Return zero and set
255| unfl, aunfl, and ainex.
256|
257fix_unfl:
258 orl #unfl_inx_mask,USER_FPSR(%a6)
259 btstb #5,FPCR_MODE(%a6) |test if rm or rp
260 beqs no_dir2
261 btstb #4,FPCR_MODE(%a6) |check which one
262 beqs zer_rm2
263zer_rp2:
264 tstb L_SCR1(%a6) |check sign
265 bnes no_dir2 |if set, neg op, no inc
266 clrl FPTEMP_EX(%a6)
267 clrl FPTEMP_HI(%a6)
268 movel #1,FPTEMP_LO(%a6) |set lsb
269 bras sm_dnrm |return smallest denorm
270zer_rm2:
271 tstb L_SCR1(%a6) |check sign
272 beqs no_dir2 |if clr, neg op, no inc
273 movew #0x8000,FPTEMP_EX(%a6)
274 clrl FPTEMP_HI(%a6)
275 movel #1,FPTEMP_LO(%a6) |set lsb
276 orl #neg_mask,USER_FPSR(%a6) |set N
277 bra sm_dnrm |return smallest denorm
278
279no_dir2:
280 tstb L_SCR1(%a6)
281 bges pos_zero
282neg_zero:
283 clrl FP_SCR1(%a6) |clear the exceptional operand
284 clrl FP_SCR1+4(%a6) |for gen_except.
285 clrl FP_SCR1+8(%a6)
286 fmoves #0x80000000,%fp0
287 rts
288pos_zero:
289 clrl FP_SCR1(%a6) |clear the exceptional operand
290 clrl FP_SCR1+4(%a6) |for gen_except.
291 clrl FP_SCR1+8(%a6)
292 fmoves #0x00000000,%fp0
293 rts
294
295|
296| The destination is a denormalized number. It must be handled
297| by first shifting the bits in the mantissa until it is normalized,
298| then adding the remainder of the source to the exponent.
299|
300dst_dnrm:
301 moveml %d2/%d3,-(%a7)
302 movew FPTEMP_EX(%a6),%d1
303 movel FPTEMP_HI(%a6),%d2
304 movel FPTEMP_LO(%a6),%d3
305dst_loop:
306 tstl %d2 |test for normalized result
307 blts dst_norm |exit loop if so
308 tstl %d0 |otherwise, test shift count
309 beqs dst_fin |if zero, shifting is done
310 subil #1,%d0 |dec src
311 lsll #1,%d3
312 roxll #1,%d2
313 bras dst_loop
314|
315| Destination became normalized. Simply add the remaining
316| portion of the src to the exponent.
317|
318dst_norm:
319 addw %d0,%d1 |dst is normalized; add src
320 tstb L_SCR1(%a6)
321 beqs dnrm_pos
322 orl #0x8000,%d1
323dnrm_pos:
324 movemw %d1,FPTEMP_EX(%a6)
325 moveml %d2,FPTEMP_HI(%a6)
326 moveml %d3,FPTEMP_LO(%a6)
327 fmovel USER_FPCR(%a6),%FPCR
328 fmovex FPTEMP(%a6),%fp0
329 moveml (%a7)+,%d2/%d3
330 rts
331
332|
333| Destination remained denormalized. Call t_excdnrm with
334| exceptional operand in ETEMP.
335|
336dst_fin:
337 tstb L_SCR1(%a6) |check for sign
338 beqs dst_exit
339 orl #neg_mask,USER_FPSR(%a6) |set N
340 orl #0x8000,%d1
341dst_exit:
342 movemw %d1,ETEMP_EX(%a6)
343 moveml %d2,ETEMP_HI(%a6)
344 moveml %d3,ETEMP_LO(%a6)
345 orl #unfl_mask,USER_FPSR(%a6) |set unfl
346 moveml (%a7)+,%d2/%d3
347 leal ETEMP(%a6),%a0
348 bra t_resdnrm
349
350|
351| Source is outside of 2^14 range. Test the sign and branch
352| to the appropriate exception handler.
353|
354src_out:
355 tstb L_SCR1(%a6)
356 beqs scro_pos
357 orl #0x8000,%d1
358scro_pos:
359 movel FPTEMP_HI(%a6),ETEMP_HI(%a6)
360 movel FPTEMP_LO(%a6),ETEMP_LO(%a6)
361 tstw ETEMP(%a6)
362 blts res_neg
363res_pos:
364 movew %d1,ETEMP(%a6) |result in ETEMP
365 bra t_ovfl2
366res_neg:
367 movew %d1,ETEMP(%a6) |result in ETEMP
368 leal ETEMP(%a6),%a0
369 bra t_unfl
370 |end