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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 17:43:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 17:43:51 +0000 |
commit | be58c81aff4cd4c0ccf43dbd7998da4a6a08c03b (patch) | |
tree | 779c248fb61c83f65d1f0dc867f2053d76b4e03a /lib/compiler-rt/builtins/popcountdi2.c | |
parent | Initial commit. (diff) | |
download | arm-trusted-firmware-upstream.tar.xz arm-trusted-firmware-upstream.zip |
Adding upstream version 2.10.0+dfsg.upstream/2.10.0+dfsgupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/compiler-rt/builtins/popcountdi2.c')
-rw-r--r-- | lib/compiler-rt/builtins/popcountdi2.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/lib/compiler-rt/builtins/popcountdi2.c b/lib/compiler-rt/builtins/popcountdi2.c new file mode 100644 index 0000000..20dd0b0 --- /dev/null +++ b/lib/compiler-rt/builtins/popcountdi2.c @@ -0,0 +1,32 @@ +//===-- popcountdi2.c - Implement __popcountdi2 ---------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements __popcountdi2 for the compiler_rt library. +// +//===----------------------------------------------------------------------===// + +#include "int_lib.h" + +// Returns: count of 1 bits + +COMPILER_RT_ABI int __popcountdi2(di_int a) { + du_int x2 = (du_int)a; + x2 = x2 - ((x2 >> 1) & 0x5555555555555555uLL); + // Every 2 bits holds the sum of every pair of bits (32) + x2 = ((x2 >> 2) & 0x3333333333333333uLL) + (x2 & 0x3333333333333333uLL); + // Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16) + x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0FuLL; + // Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8) + su_int x = (su_int)(x2 + (x2 >> 32)); + // The lower 32 bits hold four 16 bit sums (5 significant bits). + // Upper 32 bits are garbage + x = x + (x >> 16); + // The lower 16 bits hold two 32 bit sums (6 significant bits). + // Upper 16 bits are garbage + return (x + (x >> 8)) & 0x0000007F; // (7 significant bits) +} |