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1/* Copyright (C) 1996-2019 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Richard Henderson <rth@tamu.edu>.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library. If not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include "div_libc.h"
20
21#undef FRAME
22#ifdef __alpha_fix__
23#define FRAME 0
24#else
25#define FRAME 16
26#endif
27
28#undef X
29#undef Y
30#define X $17
31#define Y $18
32
33 .set noat
34
35 .align 4
36 .globl ldiv
37 .ent ldiv
38ldiv:
39 .frame sp, FRAME, ra
40#if FRAME > 0
41 lda sp, -FRAME(sp)
42#endif
43#ifdef PROF
44 .set macro
45 ldgp gp, 0(pv)
46 lda AT, _mcount
47 jsr AT, (AT), _mcount
48 .set nomacro
49 .prologue 1
50#else
51 .prologue 0
52#endif
53
54 beq Y, $divbyzero
55 excb
56 mf_fpcr $f10
57
58 _ITOFT2 X, $f0, 0, Y, $f1, 8
59
60 .align 4
61 cvtqt $f0, $f0
62 cvtqt $f1, $f1
63 divt/c $f0, $f1, $f0
64 unop
65
66 /* Check to see if X fit in the double as an exact value. */
67 sll X, (64-53), AT
68 sra AT, (64-53), AT
69 cmpeq X, AT, AT
70 beq AT, $x_big
71
72 /* If we get here, we're expecting exact results from the division.
73 Do nothing else besides convert and clean up. */
74 cvttq/c $f0, $f0
75 excb
76 mt_fpcr $f10
77 _FTOIT $f0, $0, 0
78
79$egress:
80 mulq $0, Y, $1
81 subq X, $1, $1
82
83 stq $0, 0($16)
84 stq $1, 8($16)
85 mov $16, $0
86
87#if FRAME > 0
88 lda sp, FRAME(sp)
89#endif
90 ret
91
92 .align 4
93$x_big:
94 /* If we get here, X is large enough that we don't expect exact
95 results, and neither X nor Y got mis-translated for the fp
96 division. Our task is to take the fp result, figure out how
97 far it's off from the correct result and compute a fixup. */
98
99#define Q v0 /* quotient */
100#define R t0 /* remainder */
101#define SY t1 /* scaled Y */
102#define S t2 /* scalar */
103#define QY t3 /* Q*Y */
104
105 /* The fixup code below can only handle unsigned values. */
106 or X, Y, AT
107 mov $31, t5
108 blt AT, $fix_sign_in
109$fix_sign_in_ret1:
110 cvttq/c $f0, $f0
111
112 _FTOIT $f0, Q, 8
113$fix_sign_in_ret2:
114 mulq Q, Y, QY
115 excb
116 mt_fpcr $f10
117
118 .align 4
119 subq QY, X, R
120 mov Y, SY
121 mov 1, S
122 bgt R, $q_high
123
124$q_high_ret:
125 subq X, QY, R
126 mov Y, SY
127 mov 1, S
128 bgt R, $q_low
129
130$q_low_ret:
131 negq Q, t4
132 cmovlbs t5, t4, Q
133 br $egress
134
135 .align 4
136 /* The quotient that we computed was too large. We need to reduce
137 it by S such that Y*S >= R. Obviously the closer we get to the
138 correct value the better, but overshooting high is ok, as we'll
139 fix that up later. */
1400:
141 addq SY, SY, SY
142 addq S, S, S
143$q_high:
144 cmpult SY, R, AT
145 bne AT, 0b
146
147 subq Q, S, Q
148 unop
149 subq QY, SY, QY
150 br $q_high_ret
151
152 .align 4
153 /* The quotient that we computed was too small. Divide Y by the
154 current remainder (R) and add that to the existing quotient (Q).
155 The expectation, of course, is that R is much smaller than X. */
156 /* Begin with a shift-up loop. Compute S such that Y*S >= R. We
157 already have a copy of Y in SY and the value 1 in S. */
1580:
159 addq SY, SY, SY
160 addq S, S, S
161$q_low:
162 cmpult SY, R, AT
163 bne AT, 0b
164
165 /* Shift-down and subtract loop. Each iteration compares our scaled
166 Y (SY) with the remainder (R); if SY <= R then X is divisible by
167 Y's scalar (S) so add it to the quotient (Q). */
1682: addq Q, S, t3
169 srl S, 1, S
170 cmpule SY, R, AT
171 subq R, SY, t4
172
173 cmovne AT, t3, Q
174 cmovne AT, t4, R
175 srl SY, 1, SY
176 bne S, 2b
177
178 br $q_low_ret
179
180 .align 4
181$fix_sign_in:
182 /* If we got here, then X|Y is negative. Need to adjust everything
183 such that we're doing unsigned division in the fixup loop. */
184 /* T5 is true if result should be negative. */
185 xor X, Y, AT
186 cmplt AT, 0, t5
187 cmplt X, 0, AT
188 negq X, t0
189
190 cmovne AT, t0, X
191 cmplt Y, 0, AT
192 negq Y, t0
193
194 cmovne AT, t0, Y
195 blbc t5, $fix_sign_in_ret1
196
197 cvttq/c $f0, $f0
198 _FTOIT $f0, Q, 8
199 .align 3
200 negq Q, Q
201 br $fix_sign_in_ret2
202
203$divbyzero:
204 mov a0, v0
205 lda a0, GEN_INTDIV
206 call_pal PAL_gentrap
207 stq zero, 0(v0)
208 stq zero, 8(v0)
209
210#if FRAME > 0
211 lda sp, FRAME(sp)
212#endif
213 ret
214
215 .end ldiv
216
217weak_alias (ldiv, lldiv)
218weak_alias (ldiv, imaxdiv)
219

Warning: That file was not part of the compilation database. It may have many parsing errors.