1 /* ===-- udivmodti4.c - Implement __udivmodti4 -----------------------------===
3 * The LLVM Compiler Infrastructure
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
8 * ===----------------------------------------------------------------------===
10 * This file implements __udivmodti4 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
19 /* Effects: if rem != 0, *rem = a % b
23 /* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */
25 COMPILER_RT_ABI tu_int
26 __udivmodti4(tu_int a, tu_int b, tu_int* rem)
28 const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT;
29 const unsigned n_utword_bits = sizeof(tu_int) * CHAR_BIT;
37 /* special cases, X is unknown, K != 0 */
47 *rem = n.s.low % d.s.low;
48 return n.s.low / d.s.low;
68 *rem = n.s.high % d.s.low;
69 return n.s.high / d.s.low;
80 r.s.high = n.s.high % d.s.high;
84 return n.s.high / d.s.high;
90 if ((d.s.high & (d.s.high - 1)) == 0) /* if d is a power of 2 */
95 r.s.high = n.s.high & (d.s.high - 1);
98 return n.s.high >> __builtin_ctzll(d.s.high);
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)
113 /* 1 <= sr <= n_udword_bits - 1 */
114 /* q.all = n.all << (n_utword_bits - sr); */
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);
121 else /* d.s.low != 0 */
129 if ((d.s.low & (d.s.low - 1)) == 0) /* if d is a power of 2 */
132 *rem = n.s.low & (d.s.low - 1);
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);
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;
150 if (sr == n_udword_bits)
157 else if (sr < n_udword_bits) // 2 <= sr <= n_udword_bits - 1
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);
164 else // n_udword_bits + 1 <= sr <= n_utword_bits - 1
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));
170 r.s.low = n.s.high >> (sr - n_udword_bits);
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)
188 /* 1 <= sr <= n_udword_bits
189 * q.all = n.all << (n_utword_bits - sr);
190 * r.all = n.all >> sr;
193 if (sr == n_udword_bits)
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);
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
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;
222 * if (r.all >= d.all)
228 const ti_int s = (ti_int)(d.all - r.all - 1) >> (n_utword_bits - 1);
232 q.all = (q.all << 1) | carry;
238 #endif /* CRT_HAS_128BIT */