lib/builtins/moddi3.c

   1 /*===-- moddi3.c - Implement __moddi3 -------------------------------------===
   2  *
   3  *                    The LLVM Compiler Infrastructure
   4  *
   5  * This file is dual licensed under the MIT and the University of Illinois Open
   6  * Source Licenses. See LICENSE.TXT for details.
   7  *
   8  * ===----------------------------------------------------------------------===
   9  *
  10  * This file implements __moddi3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 /* Returns: a % b */
  18
  19 COMPILER_RT_ABI di_int
  20 __moddi3(di_int a, di_int b)
  21 {
  22     const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
  23     di_int s = b >> bits_in_dword_m1;  /* s = b < 0 ? -1 : 0 */
  24     b = (b ^ s) - s;                   /* negate if s == -1 */
  25     s = a >> bits_in_dword_m1;         /* s = a < 0 ? -1 : 0 */
  26     a = (a ^ s) - s;                   /* negate if s == -1 */
  27     du_int r;
  28     __udivmoddi4(a, b, &r);
  29     return ((di_int)r ^ s) - s;                /* negate if s == -1 */
  30 }