lib/divdi3.c

   1 /* ===-- divdi3.c - Implement __divdi3 -------------------------------------===
   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 __divdi3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 du_int COMPILER_RT_ABI __udivmoddi4(du_int a, du_int b, du_int* rem);
  18
  19 /* Returns: a / b */
  20
  21 COMPILER_RT_ABI di_int
  22 __divdi3(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_a = a >> bits_in_dword_m1;           /* s_a = a < 0 ? -1 : 0 */
  26     di_int s_b = b >> bits_in_dword_m1;           /* s_b = b < 0 ? -1 : 0 */
  27     a = (a ^ s_a) - s_a;                         /* negate if s_a == -1 */
  28     b = (b ^ s_b) - s_b;                         /* negate if s_b == -1 */
  29     s_a ^= s_b;                                  /*sign of quotient */
  30     return (__udivmoddi4(a, b, (du_int*)0) ^ s_a) - s_a;  /* negate if s_a == -1 */
  31 }