lib/moddi3.c

//===-- moddi3.c - Implement __moddi3 -------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __moddi3 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
__moddi3(di_int a, di_int b)
{
    const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
    di_int s = b >> bits_in_dword_m1;  // s = b < 0 ? -1 : 0
    b = (b ^ s) - s;                   // negate if s == -1
    s = a >> bits_in_dword_m1;         // s = a < 0 ? -1 : 0
    a = (a ^ s) - s;                   // negate if s == -1
    di_int r;
    __udivmoddi4(a, b, (du_int*)&r);
    return (r ^ s) - s;                // negate if s == -1
}