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 | |
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 | |