1 //===-- divsi3.c - Implement __divsi3 -------------------------------------===// 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 __divsi3 for the compiler_rt library. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "int_lib.h" 14 15 // Returns: a / b 16 17 COMPILER_RT_ABI si_int __divsi3(si_int a, si_int b) { 18 const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1; 19 si_int s_a = a >> bits_in_word_m1; // s_a = a < 0 ? -1 : 0 20 si_int s_b = b >> bits_in_word_m1; // s_b = b < 0 ? -1 : 0 21 a = (a ^ s_a) - s_a; // negate if s_a == -1 22 b = (b ^ s_b) - s_b; // negate if s_b == -1 23 s_a ^= s_b; // sign of quotient 24 // 25 // On CPUs without unsigned hardware division support, 26 // this calls __udivsi3 (notice the cast to su_int). 27 // On CPUs with unsigned hardware division support, 28 // this uses the unsigned division instruction. 29 // 30 return ((su_int)a / (su_int)b ^ s_a) - s_a; // negate if s_a == -1 31 } 32 33 #if defined(__ARM_EABI__) 34 COMPILER_RT_ALIAS(__divsi3, __aeabi_idiv) 35 #endif 36