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1 | /* ===-- udivmodti4.c - Implement __udivmodti4 -----------------------------=== |
2 | * | |
3 | * The LLVM Compiler Infrastructure | |
4 | * | |
5 | * This file is dual licensed under the MIT and the University of Illinois Open | |
6 | * Source Licenses. See LICENSE.TXT for details. | |
7 | * | |
8 | * ===----------------------------------------------------------------------=== | |
9 | * | |
10 | * This file implements __udivmodti4 for the compiler_rt library. | |
11 | * | |
12 | * ===----------------------------------------------------------------------=== | |
13 | */ | |
14 | ||
15 | #include "int_lib.h" | |
16 | ||
17 | #ifdef CRT_HAS_128BIT | |
18 | ||
19 | /* Effects: if rem != 0, *rem = a % b | |
20 | * Returns: a / b | |
21 | */ | |
22 | ||
23 | /* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */ | |
24 | ||
25 | COMPILER_RT_ABI tu_int | |
26 | __udivmodti4(tu_int a, tu_int b, tu_int* rem) | |
27 | { | |
28 | const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT; | |
29 | const unsigned n_utword_bits = sizeof(tu_int) * CHAR_BIT; | |
30 | utwords n; | |
31 | n.all = a; | |
32 | utwords d; | |
33 | d.all = b; | |
34 | utwords q; | |
35 | utwords r; | |
36 | unsigned sr; | |
37 | /* special cases, X is unknown, K != 0 */ | |
38 | if (n.s.high == 0) | |
39 | { | |
40 | if (d.s.high == 0) | |
41 | { | |
42 | /* 0 X | |
43 | * --- | |
44 | * 0 X | |
45 | */ | |
46 | if (rem) | |
47 | *rem = n.s.low % d.s.low; | |
48 | return n.s.low / d.s.low; | |
49 | } | |
50 | /* 0 X | |
51 | * --- | |
52 | * K X | |
53 | */ | |
54 | if (rem) | |
55 | *rem = n.s.low; | |
56 | return 0; | |
57 | } | |
58 | /* n.s.high != 0 */ | |
59 | if (d.s.low == 0) | |
60 | { | |
61 | if (d.s.high == 0) | |
62 | { | |
63 | /* K X | |
64 | * --- | |
65 | * 0 0 | |
66 | */ | |
67 | if (rem) | |
68 | *rem = n.s.high % d.s.low; | |
69 | return n.s.high / d.s.low; | |
70 | } | |
71 | /* d.s.high != 0 */ | |
72 | if (n.s.low == 0) | |
73 | { | |
74 | /* K 0 | |
75 | * --- | |
76 | * K 0 | |
77 | */ | |
78 | if (rem) | |
79 | { | |
80 | r.s.high = n.s.high % d.s.high; | |
81 | r.s.low = 0; | |
82 | *rem = r.all; | |
83 | } | |
84 | return n.s.high / d.s.high; | |
85 | } | |
86 | /* K K | |
87 | * --- | |
88 | * K 0 | |
89 | */ | |
90 | if ((d.s.high & (d.s.high - 1)) == 0) /* if d is a power of 2 */ | |
91 | { | |
92 | if (rem) | |
93 | { | |
94 | r.s.low = n.s.low; | |
95 | r.s.high = n.s.high & (d.s.high - 1); | |
96 | *rem = r.all; | |
97 | } | |
98 | return n.s.high >> __builtin_ctzll(d.s.high); | |
99 | } | |
100 | /* K K | |
101 | * --- | |
102 | * K 0 | |
103 | */ | |
104 | sr = __builtin_clzll(d.s.high) - __builtin_clzll(n.s.high); | |
105 | /* 0 <= sr <= n_udword_bits - 2 or sr large */ | |
106 | if (sr > n_udword_bits - 2) | |
107 | { | |
108 | if (rem) | |
109 | *rem = n.all; | |
110 | return 0; | |
111 | } | |
112 | ++sr; | |
113 | /* 1 <= sr <= n_udword_bits - 1 */ | |
114 | /* q.all = n.all << (n_utword_bits - sr); */ | |
115 | q.s.low = 0; | |
116 | q.s.high = n.s.low << (n_udword_bits - sr); | |
117 | /* r.all = n.all >> sr; */ | |
118 | r.s.high = n.s.high >> sr; | |
119 | r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); | |
120 | } | |
121 | else /* d.s.low != 0 */ | |
122 | { | |
123 | if (d.s.high == 0) | |
124 | { | |
125 | /* K X | |
126 | * --- | |
127 | * 0 K | |
128 | */ | |
129 | if ((d.s.low & (d.s.low - 1)) == 0) /* if d is a power of 2 */ | |
130 | { | |
131 | if (rem) | |
132 | *rem = n.s.low & (d.s.low - 1); | |
133 | if (d.s.low == 1) | |
134 | return n.all; | |
135 | sr = __builtin_ctzll(d.s.low); | |
136 | q.s.high = n.s.high >> sr; | |
137 | q.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); | |
138 | return q.all; | |
139 | } | |
140 | /* K X | |
141 | * --- | |
142 | * 0 K | |
143 | */ | |
144 | sr = 1 + n_udword_bits + __builtin_clzll(d.s.low) | |
145 | - __builtin_clzll(n.s.high); | |
146 | /* 2 <= sr <= n_utword_bits - 1 | |
147 | * q.all = n.all << (n_utword_bits - sr); | |
148 | * r.all = n.all >> sr; | |
149 | */ | |
150 | if (sr == n_udword_bits) | |
151 | { | |
152 | q.s.low = 0; | |
153 | q.s.high = n.s.low; | |
154 | r.s.high = 0; | |
155 | r.s.low = n.s.high; | |
156 | } | |
157 | else if (sr < n_udword_bits) // 2 <= sr <= n_udword_bits - 1 | |
158 | { | |
159 | q.s.low = 0; | |
160 | q.s.high = n.s.low << (n_udword_bits - sr); | |
161 | r.s.high = n.s.high >> sr; | |
162 | r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); | |
163 | } | |
164 | else // n_udword_bits + 1 <= sr <= n_utword_bits - 1 | |
165 | { | |
166 | q.s.low = n.s.low << (n_utword_bits - sr); | |
167 | q.s.high = (n.s.high << (n_utword_bits - sr)) | | |
168 | (n.s.low >> (sr - n_udword_bits)); | |
169 | r.s.high = 0; | |
170 | r.s.low = n.s.high >> (sr - n_udword_bits); | |
171 | } | |
172 | } | |
173 | else | |
174 | { | |
175 | /* K X | |
176 | * --- | |
177 | * K K | |
178 | */ | |
179 | sr = __builtin_clzll(d.s.high) - __builtin_clzll(n.s.high); | |
180 | /*0 <= sr <= n_udword_bits - 1 or sr large */ | |
181 | if (sr > n_udword_bits - 1) | |
182 | { | |
183 | if (rem) | |
184 | *rem = n.all; | |
185 | return 0; | |
186 | } | |
187 | ++sr; | |
188 | /* 1 <= sr <= n_udword_bits | |
189 | * q.all = n.all << (n_utword_bits - sr); | |
190 | * r.all = n.all >> sr; | |
191 | */ | |
192 | q.s.low = 0; | |
193 | if (sr == n_udword_bits) | |
194 | { | |
195 | q.s.high = n.s.low; | |
196 | r.s.high = 0; | |
197 | r.s.low = n.s.high; | |
198 | } | |
199 | else | |
200 | { | |
201 | r.s.high = n.s.high >> sr; | |
202 | r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); | |
203 | q.s.high = n.s.low << (n_udword_bits - sr); | |
204 | } | |
205 | } | |
206 | } | |
207 | /* Not a special case | |
208 | * q and r are initialized with: | |
209 | * q.all = n.all << (n_utword_bits - sr); | |
210 | * r.all = n.all >> sr; | |
211 | * 1 <= sr <= n_utword_bits - 1 | |
212 | */ | |
213 | su_int carry = 0; | |
214 | for (; sr > 0; --sr) | |
215 | { | |
216 | /* r:q = ((r:q) << 1) | carry */ | |
217 | r.s.high = (r.s.high << 1) | (r.s.low >> (n_udword_bits - 1)); | |
218 | r.s.low = (r.s.low << 1) | (q.s.high >> (n_udword_bits - 1)); | |
219 | q.s.high = (q.s.high << 1) | (q.s.low >> (n_udword_bits - 1)); | |
220 | q.s.low = (q.s.low << 1) | carry; | |
221 | /* carry = 0; | |
222 | * if (r.all >= d.all) | |
223 | * { | |
224 | * r.all -= d.all; | |
225 | * carry = 1; | |
226 | * } | |
227 | */ | |
228 | const ti_int s = (ti_int)(d.all - r.all - 1) >> (n_utword_bits - 1); | |
229 | carry = s & 1; | |
230 | r.all -= d.all & s; | |
231 | } | |
232 | q.all = (q.all << 1) | carry; | |
233 | if (rem) | |
234 | *rem = r.all; | |
235 | return q.all; | |
236 | } | |
237 | ||
238 | #endif /* CRT_HAS_128BIT */ |