divsi3.c revision 222656 
1/* ===-- divsi3.c - Implement __divsi3 -------------------------------------===
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 __divsi3 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14#include "abi.h"
15
16#include "int_lib.h"
17
18su_int COMPILER_RT_ABI __udivsi3(su_int n, su_int d);
19
20/* Returns: a / b */
21
22ARM_EABI_FNALIAS(idiv, divsi3);
23
24COMPILER_RT_ABI si_int
25__divsi3(si_int a, si_int b)
26{
27    const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1;
28    si_int s_a = a >> bits_in_word_m1;           /* s_a = a < 0 ? -1 : 0 */
29    si_int s_b = b >> bits_in_word_m1;           /* s_b = b < 0 ? -1 : 0 */
30    a = (a ^ s_a) - s_a;                         /* negate if s_a == -1 */
31    b = (b ^ s_b) - s_b;                         /* negate if s_b == -1 */
32    s_a ^= s_b;                                  /* sign of quotient */
33    return (__udivsi3(a, b) ^ s_a) - s_a;        /* negate if s_a == -1 */
34}
35