1 /* ===-- udivmoddi4.c - Implement __udivmoddi4 -----------------------------===
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 __udivmoddi4 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
17 /* Effects: if rem != 0, *rem = a % b
21 /* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */
23 ARM_EABI_FNALIAS(uldivmod, udivmoddi4);
25 COMPILER_RT_ABI du_int
26 __udivmoddi4(du_int a, du_int b, du_int* rem)
28 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
29 const unsigned n_udword_bits = sizeof(du_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_ctz(d.s.high);
104 sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
105 /* 0 <= sr <= n_uword_bits - 2 or sr large */
106 if (sr > n_uword_bits - 2)
113 /* 1 <= sr <= n_uword_bits - 1 */
114 /* q.all = n.all << (n_udword_bits - sr); */
116 q.s.high = n.s.low << (n_uword_bits - sr);
117 /* r.all = n.all >> sr; */
118 r.s.high = n.s.high >> sr;
119 r.s.low = (n.s.high << (n_uword_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_ctz(d.s.low);
136 q.s.high = n.s.high >> sr;
137 q.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
144 sr = 1 + n_uword_bits + __builtin_clz(d.s.low) - __builtin_clz(n.s.high);
145 /* 2 <= sr <= n_udword_bits - 1
146 * q.all = n.all << (n_udword_bits - sr);
147 * r.all = n.all >> sr;
148 * if (sr == n_uword_bits)
151 * q.s.high = n.s.low;
153 * r.s.low = n.s.high;
155 * else if (sr < n_uword_bits) // 2 <= sr <= n_uword_bits - 1
158 * q.s.high = n.s.low << (n_uword_bits - sr);
159 * r.s.high = n.s.high >> sr;
160 * r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
162 * else // n_uword_bits + 1 <= sr <= n_udword_bits - 1
164 * q.s.low = n.s.low << (n_udword_bits - sr);
165 * q.s.high = (n.s.high << (n_udword_bits - sr)) |
166 * (n.s.low >> (sr - n_uword_bits));
168 * r.s.low = n.s.high >> (sr - n_uword_bits);
171 q.s.low = (n.s.low << (n_udword_bits - sr)) &
172 ((si_int)(n_uword_bits - sr) >> (n_uword_bits-1));
173 q.s.high = ((n.s.low << ( n_uword_bits - sr)) &
174 ((si_int)(sr - n_uword_bits - 1) >> (n_uword_bits-1))) |
175 (((n.s.high << (n_udword_bits - sr)) |
176 (n.s.low >> (sr - n_uword_bits))) &
177 ((si_int)(n_uword_bits - sr) >> (n_uword_bits-1)));
178 r.s.high = (n.s.high >> sr) &
179 ((si_int)(sr - n_uword_bits) >> (n_uword_bits-1));
180 r.s.low = ((n.s.high >> (sr - n_uword_bits)) &
181 ((si_int)(n_uword_bits - sr - 1) >> (n_uword_bits-1))) |
182 (((n.s.high << (n_uword_bits - sr)) |
184 ((si_int)(sr - n_uword_bits) >> (n_uword_bits-1)));
192 sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
193 /* 0 <= sr <= n_uword_bits - 1 or sr large */
194 if (sr > n_uword_bits - 1)
201 /* 1 <= sr <= n_uword_bits */
202 /* q.all = n.all << (n_udword_bits - sr); */
204 q.s.high = n.s.low << (n_uword_bits - sr);
205 /* r.all = n.all >> sr;
206 * if (sr < n_uword_bits)
208 * r.s.high = n.s.high >> sr;
209 * r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
214 * r.s.low = n.s.high;
217 r.s.high = (n.s.high >> sr) &
218 ((si_int)(sr - n_uword_bits) >> (n_uword_bits-1));
219 r.s.low = (n.s.high << (n_uword_bits - sr)) |
221 ((si_int)(sr - n_uword_bits) >> (n_uword_bits-1)));
224 /* Not a special case
225 * q and r are initialized with:
226 * q.all = n.all << (n_udword_bits - sr);
227 * r.all = n.all >> sr;
228 * 1 <= sr <= n_udword_bits - 1
233 /* r:q = ((r:q) << 1) | carry */
234 r.s.high = (r.s.high << 1) | (r.s.low >> (n_uword_bits - 1));
235 r.s.low = (r.s.low << 1) | (q.s.high >> (n_uword_bits - 1));
236 q.s.high = (q.s.high << 1) | (q.s.low >> (n_uword_bits - 1));
237 q.s.low = (q.s.low << 1) | carry;
239 * if (r.all >= d.all)
245 const di_int s = (di_int)(d.all - r.all - 1) >> (n_udword_bits - 1);
249 q.all = (q.all << 1) | carry;