1 //===-- udivsi3.c - Implement __udivsi3 -----------------------------------===// 2 // 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 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements __udivsi3 for the compiler_rt library. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "int_lib.h" 14 15 // Returns: a / b 16 17 // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide 18 19 // This function should not call __divsi3! 20 COMPILER_RT_ABI su_int __udivsi3(su_int n, su_int d) { 21 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; 22 su_int q; 23 su_int r; 24 unsigned sr; 25 // special cases 26 if (d == 0) 27 return 0; // ?! 28 if (n == 0) 29 return 0; 30 sr = __builtin_clz(d) - __builtin_clz(n); 31 // 0 <= sr <= n_uword_bits - 1 or sr large 32 if (sr > n_uword_bits - 1) // d > r 33 return 0; 34 if (sr == n_uword_bits - 1) // d == 1 35 return n; 36 ++sr; 37 // 1 <= sr <= n_uword_bits - 1 38 // Not a special case 39 q = n << (n_uword_bits - sr); 40 r = n >> sr; 41 su_int carry = 0; 42 for (; sr > 0; --sr) { 43 // r:q = ((r:q) << 1) | carry 44 r = (r << 1) | (q >> (n_uword_bits - 1)); 45 q = (q << 1) | carry; 46 // carry = 0; 47 // if (r.all >= d.all) 48 // { 49 // r.all -= d.all; 50 // carry = 1; 51 // } 52 const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); 53 carry = s & 1; 54 r -= d & s; 55 } 56 q = (q << 1) | carry; 57 return q; 58 } 59 60 #if defined(__ARM_EABI__) 61 COMPILER_RT_ALIAS(__udivsi3, __aeabi_uidiv) 62 #endif 63