mirror of
https://github.com/corda/corda.git
synced 2024-12-29 09:18:58 +00:00
45 lines
1.8 KiB
C
45 lines
1.8 KiB
C
|
/* ===-- popcountti2.c - Implement __popcountti2 ----------------------------===
|
||
|
|
*
|
||
|
|
* The LLVM Compiler Infrastructure
|
||
|
|
*
|
||
|
|
* This file is dual licensed under the MIT and the University of Illinois Open
|
||
|
|
* Source Licenses. See LICENSE.TXT for details.
|
||
|
|
*
|
||
|
|
* ===----------------------------------------------------------------------===
|
||
|
|
*
|
||
|
|
* This file implements __popcountti2 for the compiler_rt library.
|
||
|
|
*
|
||
|
|
* ===----------------------------------------------------------------------===
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "int_lib.h"
|
||
|
|
|
||
|
|
#ifdef CRT_HAS_128BIT
|
||
|
|
|
||
|
|
/* Returns: count of 1 bits */
|
||
|
|
|
||
|
|
COMPILER_RT_ABI si_int
|
||
|
|
__popcountti2(ti_int a)
|
||
|
|
{
|
||
|
|
tu_int x3 = (tu_int)a;
|
||
|
|
x3 = x3 - ((x3 >> 1) & (((tu_int)0x5555555555555555uLL << 64) |
|
||
|
|
0x5555555555555555uLL));
|
||
|
|
/* Every 2 bits holds the sum of every pair of bits (64) */
|
||
|
|
x3 = ((x3 >> 2) & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL))
|
||
|
|
+ (x3 & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL));
|
||
|
|
/* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32) */
|
||
|
|
x3 = (x3 + (x3 >> 4))
|
||
|
|
& (((tu_int)0x0F0F0F0F0F0F0F0FuLL << 64) | 0x0F0F0F0F0F0F0F0FuLL);
|
||
|
|
/* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16) */
|
||
|
|
du_int x2 = (du_int)(x3 + (x3 >> 64));
|
||
|
|
/* Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8) */
|
||
|
|
su_int x = (su_int)(x2 + (x2 >> 32));
|
||
|
|
/* Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4) */
|
||
|
|
x = x + (x >> 16);
|
||
|
|
/* Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2) */
|
||
|
|
/* Upper 16 bits are garbage */
|
||
|
|
return (x + (x >> 8)) & 0xFF; /* (8 significant bits) */
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* CRT_HAS_128BIT */
|