lib/builtins/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 #ifdef CRT_HAS_128BIT
  18
  19 /*Returns: a % b */
  20
  21 COMPILER_RT_ABI ti_int
  22 __modti3(ti_int a, ti_int b)
  23 {
  24     const int bits_in_tword_m1 = (int)(sizeof(ti_int) * CHAR_BIT) - 1;
  25     ti_int s = b >> bits_in_tword_m1;  /* s = b < 0 ? -1 : 0 */
  26     b = (b ^ s) - s;                   /* negate if s == -1 */
  27     s = a >> bits_in_tword_m1;         /* s = a < 0 ? -1 : 0 */
  28     a = (a ^ s) - s;                   /* negate if s == -1 */
  29     tu_int r;
  30     __udivmodti4(a, b, &r);
  31     return ((ti_int)r ^ s) - s;                /* negate if s == -1 */
  32 }
  33
  34 #endif /* CRT_HAS_128BIT */