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author | Anton Samokhvalov <pg83@yandex.ru> | 2022-02-10 16:45:17 +0300 |
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committer | Daniil Cherednik <dcherednik@yandex-team.ru> | 2022-02-10 16:45:17 +0300 |
commit | d3a398281c6fd1d3672036cb2d63f842d2cb28c5 (patch) | |
tree | dd4bd3ca0f36b817e96812825ffaf10d645803f2 /contrib/libs/cxxsupp/builtins/popcountsi2.c | |
parent | 72cb13b4aff9bc9cf22e49251bc8fd143f82538f (diff) | |
download | ydb-d3a398281c6fd1d3672036cb2d63f842d2cb28c5.tar.gz |
Restoring authorship annotation for Anton Samokhvalov <pg83@yandex.ru>. Commit 2 of 2.
Diffstat (limited to 'contrib/libs/cxxsupp/builtins/popcountsi2.c')
-rw-r--r-- | contrib/libs/cxxsupp/builtins/popcountsi2.c | 66 |
1 files changed, 33 insertions, 33 deletions
diff --git a/contrib/libs/cxxsupp/builtins/popcountsi2.c b/contrib/libs/cxxsupp/builtins/popcountsi2.c index 7ef6d899ee..44544ff498 100644 --- a/contrib/libs/cxxsupp/builtins/popcountsi2.c +++ b/contrib/libs/cxxsupp/builtins/popcountsi2.c @@ -1,33 +1,33 @@ -/* ===-- popcountsi2.c - Implement __popcountsi2 ---------------------------=== - * - * 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 __popcountsi2 for the compiler_rt library. - * - * ===----------------------------------------------------------------------=== - */ - -#include "int_lib.h" - -/* Returns: count of 1 bits */ - -COMPILER_RT_ABI si_int -__popcountsi2(si_int a) -{ - su_int x = (su_int)a; - x = x - ((x >> 1) & 0x55555555); - /* Every 2 bits holds the sum of every pair of bits */ - x = ((x >> 2) & 0x33333333) + (x & 0x33333333); - /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) */ - x = (x + (x >> 4)) & 0x0F0F0F0F; - /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) */ - x = (x + (x >> 16)); - /* The lower 16 bits hold two 8 bit sums (5 significant bits).*/ - /* Upper 16 bits are garbage */ - return (x + (x >> 8)) & 0x0000003F; /* (6 significant bits) */ -} +/* ===-- popcountsi2.c - Implement __popcountsi2 ---------------------------=== + * + * 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 __popcountsi2 for the compiler_rt library. + * + * ===----------------------------------------------------------------------=== + */ + +#include "int_lib.h" + +/* Returns: count of 1 bits */ + +COMPILER_RT_ABI si_int +__popcountsi2(si_int a) +{ + su_int x = (su_int)a; + x = x - ((x >> 1) & 0x55555555); + /* Every 2 bits holds the sum of every pair of bits */ + x = ((x >> 2) & 0x33333333) + (x & 0x33333333); + /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) */ + x = (x + (x >> 4)) & 0x0F0F0F0F; + /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) */ + x = (x + (x >> 16)); + /* The lower 16 bits hold two 8 bit sums (5 significant bits).*/ + /* Upper 16 bits are garbage */ + return (x + (x >> 8)) & 0x0000003F; /* (6 significant bits) */ +} |