lib/modti3.c

   1 /* ===-- modti3.c - Implement __modti3 -------------------------------------===
   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 __modti3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 #if __x86_64
  18
  19 tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
  20
  21 /*Returns: a % b */
  22
  23 ti_int
  24 __modti3(ti_int a, ti_int b)
  25 {
  26     const int bits_in_tword_m1 = (int)(sizeof(ti_int) * CHAR_BIT) - 1;
  27     ti_int s = b >> bits_in_tword_m1;  /* s = b < 0 ? -1 : 0 */
  28     b = (b ^ s) - s;                   /* negate if s == -1 */
  29     s = a >> bits_in_tword_m1;         /* s = a < 0 ? -1 : 0 */
  30     a = (a ^ s) - s;                   /* negate if s == -1 */
  31     ti_int r;
  32     __udivmodti4(a, b, (tu_int*)&r);
  33     return (r ^ s) - s;                /* negate if s == -1 */
  34 }
  35
  36 #endif