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2b778ceb | 1 | /* Copyright (C) 1996-2021 Free Software Foundation, Inc. |
60c74cf0 | 2 | This file is part of the GNU C Library. |
cb23ff1f | 3 | Contributed by Richard Henderson <rth@tamu.edu>. |
60c74cf0 UD |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or | |
3214b89b AJ |
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. | |
60c74cf0 UD |
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 | |
3214b89b | 13 | Lesser General Public License for more details. |
60c74cf0 | 14 | |
3214b89b | 15 | You should have received a copy of the GNU Lesser General Public |
ab84e3ff | 16 | License along with the GNU C Library. If not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
60c74cf0 | 18 | |
bd68d850 | 19 | #include "div_libc.h" |
60c74cf0 | 20 | |
bd68d850 RH |
21 | #undef FRAME |
22 | #ifdef __alpha_fix__ | |
23 | #define FRAME 0 | |
60c74cf0 | 24 | #else |
bd68d850 | 25 | #define FRAME 16 |
60c74cf0 UD |
26 | #endif |
27 | ||
bd68d850 RH |
28 | #undef X |
29 | #undef Y | |
30 | #define X $17 | |
31 | #define Y $18 | |
32 | ||
60c74cf0 UD |
33 | .set noat |
34 | ||
35 | .align 4 | |
36 | .globl ldiv | |
37 | .ent ldiv | |
38 | ldiv: | |
bd68d850 RH |
39 | .frame sp, FRAME, ra |
40 | #if FRAME > 0 | |
41 | lda sp, -FRAME(sp) | |
42 | #endif | |
60c74cf0 | 43 | #ifdef PROF |
bd68d850 | 44 | .set macro |
60c74cf0 UD |
45 | ldgp gp, 0(pv) |
46 | lda AT, _mcount | |
47 | jsr AT, (AT), _mcount | |
bd68d850 | 48 | .set nomacro |
60c74cf0 UD |
49 | .prologue 1 |
50 | #else | |
51 | .prologue 0 | |
52 | #endif | |
53 | ||
bd68d850 | 54 | beq Y, $divbyzero |
a61c91b0 RH |
55 | excb |
56 | mf_fpcr $f10 | |
bd68d850 RH |
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 | |
a61c91b0 RH |
75 | excb |
76 | mt_fpcr $f10 | |
bd68d850 RH |
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 | |
bd68d850 RH |
113 | $fix_sign_in_ret2: |
114 | mulq Q, Y, QY | |
a61c91b0 RH |
115 | excb |
116 | mt_fpcr $f10 | |
bd68d850 RH |
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. */ | |
140 | 0: | |
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 | |
5556231d | 153 | /* The quotient that we computed was too small. Divide Y by the |
bd68d850 RH |
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. */ | |
158 | 0: | |
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). */ | |
168 | 2: 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 | |
60c74cf0 UD |
202 | |
203 | $divbyzero: | |
204 | mov a0, v0 | |
205 | lda a0, GEN_INTDIV | |
206 | call_pal PAL_gentrap | |
60c74cf0 UD |
207 | stq zero, 0(v0) |
208 | stq zero, 8(v0) | |
60c74cf0 | 209 | |
bd68d850 RH |
210 | #if FRAME > 0 |
211 | lda sp, FRAME(sp) | |
212 | #endif | |
213 | ret | |
60c74cf0 | 214 | |
bd68d850 | 215 | .end ldiv |
228f398a RH |
216 | |
217 | weak_alias (ldiv, lldiv) | |
dc0c31fb | 218 | weak_alias (ldiv, imaxdiv) |