| //===-- udivsi3.c - Implement __udivsi3 -----------------------------------===// |
| // |
| // 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 __udivsi3 for the compiler_rt library. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "int_lib.h" |
| |
| // Returns: a / b |
| |
| // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide |
| |
| // This function should not call __divsi3! |
| COMPILER_RT_ABI su_int __udivsi3(su_int n, su_int d) { |
| const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; |
| su_int q; |
| su_int r; |
| unsigned sr; |
| // special cases |
| if (d == 0) |
| return 0; // ?! |
| if (n == 0) |
| return 0; |
| sr = __builtin_clz(d) - __builtin_clz(n); |
| // 0 <= sr <= n_uword_bits - 1 or sr large |
| if (sr > n_uword_bits - 1) // d > r |
| return 0; |
| if (sr == n_uword_bits - 1) // d == 1 |
| return n; |
| ++sr; |
| // 1 <= sr <= n_uword_bits - 1 |
| // Not a special case |
| q = n << (n_uword_bits - sr); |
| r = n >> sr; |
| su_int carry = 0; |
| for (; sr > 0; --sr) { |
| // r:q = ((r:q) << 1) | carry |
| r = (r << 1) | (q >> (n_uword_bits - 1)); |
| q = (q << 1) | carry; |
| // carry = 0; |
| // if (r.all >= d.all) |
| // { |
| // r.all -= d.all; |
| // carry = 1; |
| // } |
| const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); |
| carry = s & 1; |
| r -= d & s; |
| } |
| q = (q << 1) | carry; |
| return q; |
| } |
| |
| #if defined(__ARM_EABI__) |
| COMPILER_RT_ALIAS(__udivsi3, __aeabi_uidiv) |
| #endif |