divti3.c revision 263763 
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#ifdef CRT_HAS_128BIT
18
19tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
20
21/* Returns: a / b */
22
23ti_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 /* CRT_HAS_128BIT */
36