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1 //===-- divmodsi4.c - Implement __divmodsi4
2 //--------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements __divmodsi4 for the compiler_rt library.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "int_lib.h"
15 
16 // Returns: a / b, *rem = a % b
17 
__divmodsi4(si_int a,si_int b,si_int * rem)18 COMPILER_RT_ABI si_int __divmodsi4(si_int a, si_int b, si_int *rem) {
19   const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1;
20   si_int s_a = a >> bits_in_word_m1;                    // s_a = a < 0 ? -1 : 0
21   si_int s_b = b >> bits_in_word_m1;                    // s_b = b < 0 ? -1 : 0
22   a = (a ^ s_a) - s_a;                                  // negate if s_a == -1
23   b = (b ^ s_b) - s_b;                                  // negate if s_b == -1
24   s_b ^= s_a;                                           // sign of quotient
25   su_int r;
26   si_int q = (__udivmodsi4(a, b, &r) ^ s_b) - s_b;      // negate if s_b == -1
27   *rem = (r ^ s_a) - s_a;                               // negate if s_a == -1
28   return q;
29 }
30