xref: /freebsd/contrib/llvm-project/compiler-rt/lib/builtins/modti3.c (revision 6be3386466ab79a84b48429ae66244f21526d3df)
1 //===-- modti3.c - Implement __modti3 -------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements __modti3 for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "int_lib.h"
14 
15 #ifdef CRT_HAS_128BIT
16 
17 // Returns: a % b
18 
19 COMPILER_RT_ABI ti_int __modti3(ti_int a, ti_int b) {
20   const int bits_in_tword_m1 = (int)(sizeof(ti_int) * CHAR_BIT) - 1;
21   ti_int s = b >> bits_in_tword_m1; // s = b < 0 ? -1 : 0
22   b = (b ^ s) - s;                  // negate if s == -1
23   s = a >> bits_in_tword_m1;        // s = a < 0 ? -1 : 0
24   a = (a ^ s) - s;                  // negate if s == -1
25   tu_int r;
26   __udivmodti4(a, b, &r);
27   return ((ti_int)r ^ s) - s; // negate if s == -1
28 }
29 
30 #endif // CRT_HAS_128BIT
31