| 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 */ |
| 239 |