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
15#include "int_lib.h"
16
17su_int COMPILER_RT_ABI __udivsi3(su_int n, su_int d);
18
19/* Returns: a / b */
20
21ARM_EABI_FNALIAS(idiv, divsi3)
22
23COMPILER_RT_ABI si_int
24__divsi3(si_int a, si_int b)
25{
26    const int bits_in_word_m1 = (int)(sizeof(si_int) * CHAR_BIT) - 1;
27    si_int s_a = a >> bits_in_word_m1;           /* s_a = a < 0 ? -1 : 0 */
28    si_int s_b = b >> bits_in_word_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    /*
33     * On CPUs without unsigned hardware division support,
34     *  this calls __udivsi3 (notice the cast to su_int).
35     * On CPUs with unsigned hardware division support,
36     *  this uses the unsigned division instruction.
37     */
38    return ((su_int)a/(su_int)b ^ s_a) - s_a;    /* negate if s_a == -1 */
39}
40