lib/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 COMPILER_RT_ABI du_int __udivmoddi4(du_int a, du_int b, du_int* rem);
  18
  19 /* Returns: a % b */
  20
  21 COMPILER_RT_ABI di_int
  22 __moddi3(di_int a, di_int b)
  23 {
  24     const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
  25     di_int s = b >> bits_in_dword_m1;  /* s = b < 0 ? -1 : 0 */
  26     b = (b ^ s) - s;                   /* negate if s == -1 */
  27     s = a >> bits_in_dword_m1;         /* s = a < 0 ? -1 : 0 */
  28     a = (a ^ s) - s;                   /* negate if s == -1 */
  29     di_int r;
  30     __udivmoddi4(a, b, (du_int*)&r);
  31     return (r ^ s) - s;                /* negate if s == -1 */
  32 }