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