Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 1 | /* ===-- popcountti2.c - Implement __popcountti2 ----------------------------=== |
| 2 | * |
| 3 | * The LLVM Compiler Infrastructure |
| 4 | * |
Howard Hinnant | 9ad441f | 2010-11-16 22:13:33 +0000 | [diff] [blame] | 5 | * This file is dual licensed under the MIT and the University of Illinois Open |
| 6 | * Source Licenses. See LICENSE.TXT for details. |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | * |
| 10 | * This file implements __popcountti2 for the compiler_rt library. |
| 11 | * |
| 12 | * ===----------------------------------------------------------------------=== |
| 13 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 14 | |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 15 | #include "int_lib.h" |
| 16 | |
Chandler Carruth | 7f2d7c7 | 2012-06-22 21:09:22 +0000 | [diff] [blame^] | 17 | #if __x86_64 |
| 18 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 19 | /* Returns: count of 1 bits */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 20 | |
| 21 | si_int |
| 22 | __popcountti2(ti_int a) |
| 23 | { |
| 24 | tu_int x3 = (tu_int)a; |
| 25 | x3 = x3 - ((x3 >> 1) & (((tu_int)0x5555555555555555uLL << 64) | |
| 26 | 0x5555555555555555uLL)); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 27 | /* Every 2 bits holds the sum of every pair of bits (64) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 28 | x3 = ((x3 >> 2) & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)) |
| 29 | + (x3 & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 30 | /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 31 | x3 = (x3 + (x3 >> 4)) |
| 32 | & (((tu_int)0x0F0F0F0F0F0F0F0FuLL << 64) | 0x0F0F0F0F0F0F0F0FuLL); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 33 | /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 34 | du_int x2 = (du_int)(x3 + (x3 >> 64)); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 35 | /* Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 36 | su_int x = (su_int)(x2 + (x2 >> 32)); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 37 | /* Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 38 | x = x + (x >> 16); |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 39 | /* Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2) */ |
| 40 | /* Upper 16 bits are garbage */ |
| 41 | return (x + (x >> 8)) & 0xFF; /* (8 significant bits) */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 42 | } |
| 43 | |
| 44 | #endif |