lib/divti3.c

   1 /* ===-- divti3.c - Implement __divti3 -------------------------------------===
   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 __divti3 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 __divti3(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_a = a >> bits_in_tword_m1;           /* s_a = a < 0 ? -1 : 0 */
  28     ti_int s_b = b >> bits_in_tword_m1;           /* s_b = b < 0 ? -1 : 0 */
  29     a = (a ^ s_a) - s_a;                         /* negate if s_a == -1 */
  30     b = (b ^ s_b) - s_b;                         /* negate if s_b == -1 */
  31     s_a ^= s_b;                                  /* sign of quotient */
  32     return (__udivmodti4(a, b, (tu_int*)0) ^ s_a) - s_a;  /* negate if s_a == -1 */
  33 }
  34
  35 #endif