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| For details on the license for this file, please see the
55| file, README, in this same directory.
56
57|SINT idnt 2,1 | Motorola 040 Floating Point Software Package
58
59 |section 8
60
61#include "fpsp.h"
62
63 |xref dnrm_lp
64 |xref nrm_set
65 |xref round
66 |xref t_inx2
67 |xref ld_pone
68 |xref ld_mone
69 |xref ld_pzero
70 |xref ld_mzero
71 |xref snzrinx
72
73|
74| FINT
75|
76 .global sint
77sint:
78 bfextu FPCR_MODE(%a6){
79| ;implicitly has extend precision
80| ;in upper word.
81 movel %d1,L_SCR1(%a6) |save mode bits
82 bras sintexc
83
84|
85| FINT with extended denorm inputs.
86|
87 .global sintd
88sintd:
89 btstb
90 beq snzrinx |if round nearest or round zero, +/- 0
91 btstb
92 beqs rnd_mns
93rnd_pls:
94 btstb
95 bnes sintmz
96 bsr ld_pone |if round plus inf and pos, answer is +1
97 bra t_inx2
98rnd_mns:
99 btstb
100 beqs sintpz
101 bsr ld_mone |if round mns inf and neg, answer is -1
102 bra t_inx2
103sintpz:
104 bsr ld_pzero
105 bra t_inx2
106sintmz:
107 bsr ld_mzero
108 bra t_inx2
109
110|
111| FINTRZ
112|
113 .global sintrz
114sintrz:
115 movel
116| ;implicitly has extend precision
117| ;in upper word.
118 bras sintexc
119|
120| SINTDO
121|
122| Input: a0 points to an IEEE extended format operand
123| Output: fp0 has the result
124|
125| Exceptions:
126|
127| If the subroutine results in an inexact operation, the inx2 and
128| ainx bits in the USER_FPSR are set.
129|
130|
131 .global sintdo
132sintdo:
133 bfextu FPCR_MODE(%a6){
134| ;implicitly has ext precision
135| ;in upper word.
136 movel %d1,L_SCR1(%a6) |save mode bits
137|
138| Real work of sint is in sintexc
139|
140sintexc:
141 bclrb
142| ;format
143 sne LOCAL_SGN(%a0)
144 cmpw
145 bgts out_rnge |branch if exp < 63
146 cmpw
147 bgt in_rnge |if 63 >= exp > 0, do calc
148|
149| Input is less than zero. Restore sign, and check for directed
150| rounding modes. L_SCR1 contains the rmode in the lower byte.
151|
152un_rnge:
153 btstb
154 beqs un_rnrz
155 tstb LOCAL_SGN(%a0) |check for sign
156 bnes un_rmrp_neg
157|
158| Sign is +. If rp, load +1.0, if rm, load +0.0
159|
160 cmpib
161 beqs un_ldpone |if rp, load +1.0
162 bsr ld_pzero |if rm, load +0.0
163 bra t_inx2
164un_ldpone:
165 bsr ld_pone
166 bra t_inx2
167|
168| Sign is -. If rm, load -1.0, if rp, load -0.0
169|
170un_rmrp_neg:
171 cmpib
172 beqs un_ldmone |if rm, load -1.0
173 bsr ld_mzero |if rp, load -0.0
174 bra t_inx2
175un_ldmone:
176 bsr ld_mone
177 bra t_inx2
178|
179| Rmode is rn or rz; return signed zero
180|
181un_rnrz:
182 tstb LOCAL_SGN(%a0) |check for sign
183 bnes un_rnrz_neg
184 bsr ld_pzero
185 bra t_inx2
186un_rnrz_neg:
187 bsr ld_mzero
188 bra t_inx2
189
190|
191| Input is greater than 2^63. All bits are significant. Return
192| the input.
193|
194out_rnge:
195 bfclr LOCAL_SGN(%a0){
196 beqs intps
197 bsetb
198intps:
199 fmovel %fpcr,-(%sp)
200 fmovel
201 fmovex LOCAL_EX(%a0),%fp0 |if exp > 63
202| ;then return X to the user
203| ;there are no fraction bits
204 fmovel (%sp)+,%fpcr
205 rts
206
207in_rnge:
208| ;shift off fraction bits
209 clrl %d0 |clear d0 - initial g,r,s for
210| ;dnrm_lp
211 movel
212| ;assumes a0 points to operand
213 bsr dnrm_lp
214| ;returns unnormalized number
215| ;pointed by a0
216| ;output d0 supplies g,r,s
217| ;used by round
218 movel L_SCR1(%a6),%d1 |use selected rounding mode
219|
220|
221 bsr round |round the unnorm based on users
222| ;input a0 ptr to ext X
223| ; d0 g,r,s bits
224| ; d1 PREC/MODE info
225| ;output a0 ptr to rounded result
226| ;inexact flag set in USER_FPSR
227| ;if initial grs set
228|
229| normalize the rounded result and store value in fp0
230|
231 bsr nrm_set |normalize the unnorm
232| ;Input: a0 points to operand to
233| ;be normalized
234| ;Output: a0 points to normalized
235| ;result
236 bfclr LOCAL_SGN(%a0){
237 beqs nrmrndp
238 bsetb
239nrmrndp:
240 fmovel %fpcr,-(%sp)
241 fmovel
242 fmovex LOCAL_EX(%a0),%fp0 |move result to fp0
243 fmovel (%sp)+,%fpcr
244 rts
245
246 |end
247
