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Replaces PopulationCount by std::popcount

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This commit is contained in:
Vladislav Belov
2026-09-21 00:47:09 +02:00
parent ddbdee53be
commit 93eb35a618
4 changed files with 10 additions and 62 deletions
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source/lib/bits.h
+1 -38
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@@ -1,4 +1,4 @@
/* Copyright (C) 2025 Wildfire Games.
/* Copyright (C) 2026 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@@ -128,43 +128,6 @@ inline T SetBitsTo(T num, size_t lo_idx, size_t hi_idx, size_t value)
return result;
}
/**
* @return number of 1-bits in mask.
* execution time is proportional to number of 1-bits in mask.
**/
template<typename T>
inline size_t SparsePopulationCount(T mask)
{
size_t num1Bits = 0;
while(mask)
{
mask &= mask-1; // clear least significant 1-bit
num1Bits++;
}
return num1Bits;
}
/**
* @return number of 1-bits in mask.
* execution time is logarithmic in the total number of bits.
* supports up to 128-bit integers (if their arithmetic operators are defined).
* [http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel]
**/
template<typename T>
static inline size_t PopulationCount(T x)
{
cassert(!std::numeric_limits<T>::is_signed);
const T mask = T(~T(0));
x -= (x >> 1) & (mask/3); // count 2 bits
x = (x & (mask/15*3)) + ((x >> 2) & (mask/15*3)); // count 4 bits
x = (x + (x >> 4)) & (mask/255*15); // count 8 bits
return T(x * (mask/255)) >> ((sizeof(T)-1)*CHAR_BIT);
}
/**
* @return whether the given number is a power of two.
**/
source/lib/sysdep/os/win/wcpu.cpp
+4 -2
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@@ -1,4 +1,4 @@
/* Copyright (C) 2014 Wildfire Games.
/* Copyright (C) 2026 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@@ -34,6 +34,8 @@
#include "lib/sysdep/os/win/wutil.h"
#include "lib/sysdep/arch/x86_x64/x86_x64.h"
#include <bit>
uintptr_t os_cpu_ProcessorMask()
{
@@ -59,7 +61,7 @@ size_t os_cpu_NumProcessors()
if(!numProcessors)
{
numProcessors = PopulationCount(os_cpu_ProcessorMask());
numProcessors = std::popcount(os_cpu_ProcessorMask());
// sanity check
SYSTEM_INFO si;
source/lib/sysdep/os/win/wnuma.cpp
+4 -3
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@@ -1,4 +1,4 @@
/* Copyright (C) 2025 Wildfire Games.
/* Copyright (C) 2026 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@@ -23,7 +23,7 @@
#include "precompiled.h"
#include "lib/sysdep/numa.h"
#include "lib/bits.h" // PopulationCount
#include "lib/bits.h"
#include "lib/alignment.h"
#include "lib/lib.h"
#include "lib/timer.h"
@@ -35,6 +35,7 @@
#include "lib/sysdep/os/win/wutil.h"
#include "lib/sysdep/os/win/wcpu.h"
#include <bit>
#include <map>
#include <Psapi.h>
#include <utility>
@@ -117,7 +118,7 @@ static void PopulateNodes()
const BOOL ok = GetProcessAffinityMask(GetCurrentProcess(), &processAffinity, &systemAffinity);
WARN_IF_FALSE(ok);
}
ENSURE(PopulationCount(processAffinity) <= PopulationCount(systemAffinity));
ENSURE(std::popcount(processAffinity) <= std::popcount(systemAffinity));
for(UCHAR nodeNumber = 0; nodeNumber <= HighestNodeNumber(); nodeNumber++)
{
source/lib/tests/test_bits.h
+1 -19
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@@ -1,4 +1,4 @@
/* Copyright (C) 2025 Wildfire Games.
/* Copyright (C) 2026 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@@ -85,24 +85,6 @@ public:
EQUALS(bits<u64>(0xA5A5A5A5A5A5A5A5ull, 32, 63), 0xA5A5A5A5ull);
}
void test_PopulationCount()
{
EQUALS(PopulationCount<u8>(0), 0u);
EQUALS(PopulationCount<u8>(4), 1u);
EQUALS(PopulationCount<u8>(0x28), 2u);
EQUALS(PopulationCount<u8>(0xFF), 8u);
EQUALS(PopulationCount<u32>(0x0ul), 0u);
EQUALS(PopulationCount<u32>(0x8ul), 1u);
EQUALS(PopulationCount<u32>(0xFFFFul), 16u);
EQUALS(PopulationCount<u32>(0xFFFFFFFFul), 32u);
EQUALS(PopulationCount<u64>(0x0ull), 0u);
EQUALS(PopulationCount<u64>(0x10ull), 1u);
EQUALS(PopulationCount<u64>(0xFFFFull), 16u);
EQUALS(PopulationCount<u64>(0xFFFFFFFFull), 32u);
EQUALS(PopulationCount<u64>(0xFFFFFFFFFFFFFFFEull), 63u);
EQUALS(PopulationCount<u64>(0xFFFFFFFFFFFFFFFFull), 64u);
}
void test_is_pow2()
{
EQUALS(is_pow2(0u), false);