| //===-- udivmodti4.c - Implement __udivmodti4 -----------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements __udivmodti4 for the compiler_rt library. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "int_lib.h" |
| |
| #ifdef CRT_HAS_128BIT |
| |
| // Effects: if rem != 0, *rem = a % b |
| // Returns: a / b |
| |
| // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide |
| |
| COMPILER_RT_ABI tu_int __udivmodti4(tu_int a, tu_int b, tu_int *rem) { |
| const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT; |
| const unsigned n_utword_bits = sizeof(tu_int) * CHAR_BIT; |
| utwords n; |
| n.all = a; |
| utwords d; |
| d.all = b; |
| utwords q; |
| utwords r; |
| unsigned sr; |
| // special cases, X is unknown, K != 0 |
| if (n.s.high == 0) { |
| if (d.s.high == 0) { |
| // 0 X |
| // --- |
| // 0 X |
| if (rem) |
| *rem = n.s.low % d.s.low; |
| return n.s.low / d.s.low; |
| } |
| // 0 X |
| // --- |
| // K X |
| if (rem) |
| *rem = n.s.low; |
| return 0; |
| } |
| // n.s.high != 0 |
| if (d.s.low == 0) { |
| if (d.s.high == 0) { |
| // K X |
| // --- |
| // 0 0 |
| if (rem) |
| *rem = n.s.high % d.s.low; |
| return n.s.high / d.s.low; |
| } |
| // d.s.high != 0 |
| if (n.s.low == 0) { |
| // K 0 |
| // --- |
| // K 0 |
| if (rem) { |
| r.s.high = n.s.high % d.s.high; |
| r.s.low = 0; |
| *rem = r.all; |
| } |
| return n.s.high / d.s.high; |
| } |
| // K K |
| // --- |
| // K 0 |
| if ((d.s.high & (d.s.high - 1)) == 0) /* if d is a power of 2 */ { |
| if (rem) { |
| r.s.low = n.s.low; |
| r.s.high = n.s.high & (d.s.high - 1); |
| *rem = r.all; |
| } |
| return n.s.high >> __builtin_ctzll(d.s.high); |
| } |
| // K K |
| // --- |
| // K 0 |
| sr = __builtin_clzll(d.s.high) - __builtin_clzll(n.s.high); |
| // 0 <= sr <= n_udword_bits - 2 or sr large |
| if (sr > n_udword_bits - 2) { |
| if (rem) |
| *rem = n.all; |
| return 0; |
| } |
| ++sr; |
| // 1 <= sr <= n_udword_bits - 1 |
| // q.all = n.all << (n_utword_bits - sr); |
| q.s.low = 0; |
| q.s.high = n.s.low << (n_udword_bits - sr); |
| // r.all = n.all >> sr; |
| r.s.high = n.s.high >> sr; |
| r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); |
| } else /* d.s.low != 0 */ { |
| if (d.s.high == 0) { |
| // K X |
| // --- |
| // 0 K |
| if ((d.s.low & (d.s.low - 1)) == 0) /* if d is a power of 2 */ { |
| if (rem) |
| *rem = n.s.low & (d.s.low - 1); |
| if (d.s.low == 1) |
| return n.all; |
| sr = __builtin_ctzll(d.s.low); |
| q.s.high = n.s.high >> sr; |
| q.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); |
| return q.all; |
| } |
| // K X |
| // --- |
| // 0 K |
| sr = 1 + n_udword_bits + __builtin_clzll(d.s.low) - |
| __builtin_clzll(n.s.high); |
| // 2 <= sr <= n_utword_bits - 1 |
| // q.all = n.all << (n_utword_bits - sr); |
| // r.all = n.all >> sr; |
| if (sr == n_udword_bits) { |
| q.s.low = 0; |
| q.s.high = n.s.low; |
| r.s.high = 0; |
| r.s.low = n.s.high; |
| } else if (sr < n_udword_bits) /* 2 <= sr <= n_udword_bits - 1 */ { |
| q.s.low = 0; |
| q.s.high = n.s.low << (n_udword_bits - sr); |
| r.s.high = n.s.high >> sr; |
| r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); |
| } else /* n_udword_bits + 1 <= sr <= n_utword_bits - 1 */ { |
| q.s.low = n.s.low << (n_utword_bits - sr); |
| q.s.high = (n.s.high << (n_utword_bits - sr)) | |
| (n.s.low >> (sr - n_udword_bits)); |
| r.s.high = 0; |
| r.s.low = n.s.high >> (sr - n_udword_bits); |
| } |
| } else { |
| // K X |
| // --- |
| // K K |
| sr = __builtin_clzll(d.s.high) - __builtin_clzll(n.s.high); |
| // 0 <= sr <= n_udword_bits - 1 or sr large |
| if (sr > n_udword_bits - 1) { |
| if (rem) |
| *rem = n.all; |
| return 0; |
| } |
| ++sr; |
| // 1 <= sr <= n_udword_bits |
| // q.all = n.all << (n_utword_bits - sr); |
| // r.all = n.all >> sr; |
| q.s.low = 0; |
| if (sr == n_udword_bits) { |
| q.s.high = n.s.low; |
| r.s.high = 0; |
| r.s.low = n.s.high; |
| } else { |
| r.s.high = n.s.high >> sr; |
| r.s.low = (n.s.high << (n_udword_bits - sr)) | (n.s.low >> sr); |
| q.s.high = n.s.low << (n_udword_bits - sr); |
| } |
| } |
| } |
| // Not a special case |
| // q and r are initialized with: |
| // q.all = n.all << (n_utword_bits - sr); |
| // r.all = n.all >> sr; |
| // 1 <= sr <= n_utword_bits - 1 |
| su_int carry = 0; |
| for (; sr > 0; --sr) { |
| // r:q = ((r:q) << 1) | carry |
| r.s.high = (r.s.high << 1) | (r.s.low >> (n_udword_bits - 1)); |
| r.s.low = (r.s.low << 1) | (q.s.high >> (n_udword_bits - 1)); |
| q.s.high = (q.s.high << 1) | (q.s.low >> (n_udword_bits - 1)); |
| q.s.low = (q.s.low << 1) | carry; |
| // carry = 0; |
| // if (r.all >= d.all) |
| // { |
| // r.all -= d.all; |
| // carry = 1; |
| // } |
| const ti_int s = (ti_int)(d.all - r.all - 1) >> (n_utword_bits - 1); |
| carry = s & 1; |
| r.all -= d.all & s; |
| } |
| q.all = (q.all << 1) | carry; |
| if (rem) |
| *rem = r.all; |
| return q.all; |
| } |
| |
| #endif // CRT_HAS_128BIT |