compiler-rt/lib/builtins/divmoddi4.c

   1 //===-- divmoddi4.c - Implement __divmoddi4 -------------------------------===//
   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 __divmoddi4 for the compiler_rt library.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "int_lib.h"
  14
  15 // Returns: a / b, *rem = a % b
  16
  17 COMPILER_RT_ABI di_int __divmoddi4(di_int a, di_int b, di_int *rem) {
  18   const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
  19   di_int s_a = a >> bits_in_dword_m1;                   // s_a = a < 0 ? -1 : 0
  20   di_int s_b = b >> bits_in_dword_m1;                   // s_b = b < 0 ? -1 : 0
  21   a = (du_int)(a ^ s_a) - s_a;                          // negate if s_a == -1
  22   b = (du_int)(b ^ s_b) - s_b;                          // negate if s_b == -1
  23   s_b ^= s_a;                                           // sign of quotient
  24   du_int r;
  25   di_int q = (__udivmoddi4(a, b, &r) ^ s_b) - s_b;      // negate if s_b == -1
  26   *rem = (r ^ s_a) - s_a;                               // negate if s_a == -1
  27   return q;
  28 }