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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/m68k/fpsp040/sint.S
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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1|
2| sint.sa 3.1 12/10/90
3|
4| The entry point sINT computes the rounded integer
5| equivalent of the input argument, sINTRZ computes
6| the integer rounded to zero of the input argument.
7|
8| Entry points sint and sintrz are called from do_func
9| to emulate the fint and fintrz unimplemented instructions,
10| respectively. Entry point sintdo is used by bindec.
11|
12| Input: (Entry points sint and sintrz) Double-extended
13| number X in the ETEMP space in the floating-point
14| save stack.
15| (Entry point sintdo) Double-extended number X in
16| location pointed to by the address register a0.
17| (Entry point sintd) Double-extended denormalized
18| number X in the ETEMP space in the floating-point
19| save stack.
20|
21| Output: The function returns int(X) or intrz(X) in fp0.
22|
23| Modifies: fp0.
24|
25| Algorithm: (sint and sintrz)
26|
27| 1. If exp(X) >= 63, return X.
28| If exp(X) < 0, return +/- 0 or +/- 1, according to
29| the rounding mode.
30|
31| 2. (X is in range) set rsc = 63 - exp(X). Unnormalize the
32| result to the exponent $403e.
33|
34| 3. Round the result in the mode given in USER_FPCR. For
35| sintrz, force round-to-zero mode.
36|
37| 4. Normalize the rounded result; store in fp0.
38|
39| For the denormalized cases, force the correct result
40| for the given sign and rounding mode.
41|
42| Sign(X)
43| RMODE + -
44| ----- --------
45| RN +0 -0
46| RZ +0 -0
47| RM +0 -1
48| RP +1 -0
49|
50|
51| Copyright (C) Motorola, Inc. 1990
52| All Rights Reserved
53|
54| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
55| The copyright notice above does not evidence any
56| actual or intended publication of such source code.
57
58|SINT idnt 2,1 | Motorola 040 Floating Point Software Package
59
60 |section 8
61
62#include "fpsp.h"
63
64 |xref dnrm_lp
65 |xref nrm_set
66 |xref round
67 |xref t_inx2
68 |xref ld_pone
69 |xref ld_mone
70 |xref ld_pzero
71 |xref ld_mzero
72 |xref snzrinx
73
74|
75| FINT
76|
77 .global sint
78sint:
79 bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
80| ;implicitly has extend precision
81| ;in upper word.
82 movel %d1,L_SCR1(%a6) |save mode bits
83 bras sintexc
84
85|
86| FINT with extended denorm inputs.
87|
88 .global sintd
89sintd:
90 btstb #5,FPCR_MODE(%a6)
91 beq snzrinx |if round nearest or round zero, +/- 0
92 btstb #4,FPCR_MODE(%a6)
93 beqs rnd_mns
94rnd_pls:
95 btstb #sign_bit,LOCAL_EX(%a0)
96 bnes sintmz
97 bsr ld_pone |if round plus inf and pos, answer is +1
98 bra t_inx2
99rnd_mns:
100 btstb #sign_bit,LOCAL_EX(%a0)
101 beqs sintpz
102 bsr ld_mone |if round mns inf and neg, answer is -1
103 bra t_inx2
104sintpz:
105 bsr ld_pzero
106 bra t_inx2
107sintmz:
108 bsr ld_mzero
109 bra t_inx2
110
111|
112| FINTRZ
113|
114 .global sintrz
115sintrz:
116 movel #1,L_SCR1(%a6) |use rz mode for rounding
117| ;implicitly has extend precision
118| ;in upper word.
119 bras sintexc
120|
121| SINTDO
122|
123| Input: a0 points to an IEEE extended format operand
124| Output: fp0 has the result
125|
126| Exceptions:
127|
128| If the subroutine results in an inexact operation, the inx2 and
129| ainx bits in the USER_FPSR are set.
130|
131|
132 .global sintdo
133sintdo:
134 bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
135| ;implicitly has ext precision
136| ;in upper word.
137 movel %d1,L_SCR1(%a6) |save mode bits
138|
139| Real work of sint is in sintexc
140|
141sintexc:
142 bclrb #sign_bit,LOCAL_EX(%a0) |convert to internal extended
143| ;format
144 sne LOCAL_SGN(%a0)
145 cmpw #0x403e,LOCAL_EX(%a0) |check if (unbiased) exp > 63
146 bgts out_rnge |branch if exp < 63
147 cmpw #0x3ffd,LOCAL_EX(%a0) |check if (unbiased) exp < 0
148 bgt in_rnge |if 63 >= exp > 0, do calc
149|
150| Input is less than zero. Restore sign, and check for directed
151| rounding modes. L_SCR1 contains the rmode in the lower byte.
152|
153un_rnge:
154 btstb #1,L_SCR1+3(%a6) |check for rn and rz
155 beqs un_rnrz
156 tstb LOCAL_SGN(%a0) |check for sign
157 bnes un_rmrp_neg
158|
159| Sign is +. If rp, load +1.0, if rm, load +0.0
160|
161 cmpib #3,L_SCR1+3(%a6) |check for rp
162 beqs un_ldpone |if rp, load +1.0
163 bsr ld_pzero |if rm, load +0.0
164 bra t_inx2
165un_ldpone:
166 bsr ld_pone
167 bra t_inx2
168|
169| Sign is -. If rm, load -1.0, if rp, load -0.0
170|
171un_rmrp_neg:
172 cmpib #2,L_SCR1+3(%a6) |check for rm
173 beqs un_ldmone |if rm, load -1.0
174 bsr ld_mzero |if rp, load -0.0
175 bra t_inx2
176un_ldmone:
177 bsr ld_mone
178 bra t_inx2
179|
180| Rmode is rn or rz; return signed zero
181|
182un_rnrz:
183 tstb LOCAL_SGN(%a0) |check for sign
184 bnes un_rnrz_neg
185 bsr ld_pzero
186 bra t_inx2
187un_rnrz_neg:
188 bsr ld_mzero
189 bra t_inx2
190
191|
192| Input is greater than 2^63. All bits are significant. Return
193| the input.
194|
195out_rnge:
196 bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
197 beqs intps
198 bsetb #sign_bit,LOCAL_EX(%a0)
199intps:
200 fmovel %fpcr,-(%sp)
201 fmovel #0,%fpcr
202 fmovex LOCAL_EX(%a0),%fp0 |if exp > 63
203| ;then return X to the user
204| ;there are no fraction bits
205 fmovel (%sp)+,%fpcr
206 rts
207
208in_rnge:
209| ;shift off fraction bits
210 clrl %d0 |clear d0 - initial g,r,s for
211| ;dnrm_lp
212 movel #0x403e,%d1 |set threshold for dnrm_lp
213| ;assumes a0 points to operand
214 bsr dnrm_lp
215| ;returns unnormalized number
216| ;pointed by a0
217| ;output d0 supplies g,r,s
218| ;used by round
219 movel L_SCR1(%a6),%d1 |use selected rounding mode
220|
221|
222 bsr round |round the unnorm based on users
223| ;input a0 ptr to ext X
224| ; d0 g,r,s bits
225| ; d1 PREC/MODE info
226| ;output a0 ptr to rounded result
227| ;inexact flag set in USER_FPSR
228| ;if initial grs set
229|
230| normalize the rounded result and store value in fp0
231|
232 bsr nrm_set |normalize the unnorm
233| ;Input: a0 points to operand to
234| ;be normalized
235| ;Output: a0 points to normalized
236| ;result
237 bfclr LOCAL_SGN(%a0){#0:#8}
238 beqs nrmrndp
239 bsetb #sign_bit,LOCAL_EX(%a0) |return to IEEE extended format
240nrmrndp:
241 fmovel %fpcr,-(%sp)
242 fmovel #0,%fpcr
243 fmovex LOCAL_EX(%a0),%fp0 |move result to fp0
244 fmovel (%sp)+,%fpcr
245 rts
246
247 |end
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