1 //===-- popcountti2.c - Implement __popcountti2
2 //----------------------------===//
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
8 //===----------------------------------------------------------------------===//
10 // This file implements __popcountti2 for the compiler_rt library.
12 //===----------------------------------------------------------------------===//
18 // Returns: count of 1 bits
20 COMPILER_RT_ABI
int __popcountti2(ti_int a
) {
21 tu_int x3
= (tu_int
)a
;
22 x3
= x3
- ((x3
>> 1) &
23 (((tu_int
)0x5555555555555555uLL
<< 64) | 0x5555555555555555uLL
));
24 // Every 2 bits holds the sum of every pair of bits (64)
26 (((tu_int
)0x3333333333333333uLL
<< 64) | 0x3333333333333333uLL
)) +
27 (x3
& (((tu_int
)0x3333333333333333uLL
<< 64) | 0x3333333333333333uLL
));
28 // Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32)
29 x3
= (x3
+ (x3
>> 4)) &
30 (((tu_int
)0x0F0F0F0F0F0F0F0FuLL
<< 64) | 0x0F0F0F0F0F0F0F0FuLL
);
31 // Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16)
32 du_int x2
= (du_int
)(x3
+ (x3
>> 64));
33 // Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8)
34 su_int x
= (su_int
)(x2
+ (x2
>> 32));
35 // Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4)
37 // Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2)
39 // Upper 16 bits are garbage
40 return (x
+ (x
>> 8)) & 0xFF; // (8 significant bits)
43 #endif // CRT_HAS_128BIT