1 //===-- udivmoddi4.c - Implement __udivmoddi4 -----------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file implements __udivmoddi4 for the compiler_rt library.
11 //===----------------------------------------------------------------------===//
15 // Effects: if rem != 0, *rem = a % b
18 // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide
20 COMPILER_RT_ABI du_int __udivmoddi4(du_int a, du_int b, du_int *rem) {
21 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
22 const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT;
30 // special cases, X is unknown, K != 0
37 *rem = n.s.low % d.s.low;
38 return n.s.low / d.s.low;
54 *rem = n.s.high % d.s.low;
55 return n.s.high / d.s.low;
63 r.s.high = n.s.high % d.s.high;
67 return n.s.high / d.s.high;
72 if ((d.s.high & (d.s.high - 1)) == 0) /* if d is a power of 2 */ {
75 r.s.high = n.s.high & (d.s.high - 1);
78 return n.s.high >> __builtin_ctz(d.s.high);
83 sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
84 // 0 <= sr <= n_uword_bits - 2 or sr large
85 if (sr > n_uword_bits - 2) {
91 // 1 <= sr <= n_uword_bits - 1
92 // q.all = n.all << (n_udword_bits - sr);
94 q.s.high = n.s.low << (n_uword_bits - sr);
95 // r.all = n.all >> sr;
96 r.s.high = n.s.high >> sr;
97 r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
98 } else /* d.s.low != 0 */ {
103 if ((d.s.low & (d.s.low - 1)) == 0) /* if d is a power of 2 */ {
105 *rem = n.s.low & (d.s.low - 1);
108 sr = __builtin_ctz(d.s.low);
109 q.s.high = n.s.high >> sr;
110 q.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
116 sr = 1 + n_uword_bits + __builtin_clz(d.s.low) - __builtin_clz(n.s.high);
117 // 2 <= sr <= n_udword_bits - 1
118 // q.all = n.all << (n_udword_bits - sr);
119 // r.all = n.all >> sr;
120 if (sr == n_uword_bits) {
125 } else if (sr < n_uword_bits) /* 2 <= sr <= n_uword_bits - 1 */ {
127 q.s.high = n.s.low << (n_uword_bits - sr);
128 r.s.high = n.s.high >> sr;
129 r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
130 } else /* n_uword_bits + 1 <= sr <= n_udword_bits - 1 */ {
131 q.s.low = n.s.low << (n_udword_bits - sr);
132 q.s.high = (n.s.high << (n_udword_bits - sr)) |
133 (n.s.low >> (sr - n_uword_bits));
135 r.s.low = n.s.high >> (sr - n_uword_bits);
141 sr = __builtin_clz(d.s.high) - __builtin_clz(n.s.high);
142 // 0 <= sr <= n_uword_bits - 1 or sr large
143 if (sr > n_uword_bits - 1) {
149 // 1 <= sr <= n_uword_bits
150 // q.all = n.all << (n_udword_bits - sr);
152 if (sr == n_uword_bits) {
157 q.s.high = n.s.low << (n_uword_bits - sr);
158 r.s.high = n.s.high >> sr;
159 r.s.low = (n.s.high << (n_uword_bits - sr)) | (n.s.low >> sr);
163 // Not a special case
164 // q and r are initialized with:
165 // q.all = n.all << (n_udword_bits - sr);
166 // r.all = n.all >> sr;
167 // 1 <= sr <= n_udword_bits - 1
169 for (; sr > 0; --sr) {
170 // r:q = ((r:q) << 1) | carry
171 r.s.high = (r.s.high << 1) | (r.s.low >> (n_uword_bits - 1));
172 r.s.low = (r.s.low << 1) | (q.s.high >> (n_uword_bits - 1));
173 q.s.high = (q.s.high << 1) | (q.s.low >> (n_uword_bits - 1));
174 q.s.low = (q.s.low << 1) | carry;
176 // if (r.all >= d.all)
181 const di_int s = (di_int)(d.all - r.all - 1) >> (n_udword_bits - 1);
185 q.all = (q.all << 1) | carry;