xref: /external/compiler-rt/lib/builtins/divdi3.c

//===-- divdi3.c - Implement __divdi3 -------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __divdi3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//

#include "int_lib.h"

du_int __udivmoddi4(du_int a, du_int b, du_int* rem);

// Returns: a / b

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
}