xref: /freebsd-11-stable/contrib/llvm-project/compiler-rt/lib/builtins/divdi3.c

//===-- divdi3.c - Implement __divdi3 -------------------------------------===//
//
// 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 __divdi3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//

#include "int_lib.h"

// Returns: a / b

COMPILER_RT_ABI di_int __divdi3(di_int a, di_int b) {
  const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
  di_int s_a = a >> bits_in_dword_m1;                   // s_a = a < 0 ? -1 : 0
  di_int s_b = b >> bits_in_dword_m1;                   // s_b = b < 0 ? -1 : 0
  a = (a ^ s_a) - s_a;                                  // negate if s_a == -1
  b = (b ^ s_b) - s_b;                                  // negate if s_b == -1
  s_a ^= s_b;                                           // sign of quotient
  return (__udivmoddi4(a, b, (du_int *)0) ^ s_a) - s_a; // negate if s_a == -1
}