/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#if !defined(BITCOUNT_H_INCLUDED)
#define BITCOUNT_H_INCLUDED
-// To enable POPCNT support uncomment USE_POPCNT define. For PGO compile on a Core i7
-// you may want to collect profile data first with USE_POPCNT disabled and then, in a
-// second profiling session, with USE_POPCNT enabled so to exercise both paths. Don't
-// forget to leave USE_POPCNT enabled for the final optimized compile though ;-)
-
-//#define USE_POPCNT
-
-
#include "types.h"
-// Select type of intrinsic bit count instruction to use
-
-#if defined(_MSC_VER) && defined(IS_64BIT) && defined(USE_POPCNT) // Microsoft compiler
-
-#include <intrin.h>
-
-inline bool cpu_has_popcnt() {
-
- int CPUInfo[4] = {-1};
- __cpuid(CPUInfo, 0x00000001);
- return (CPUInfo[2] >> 23) & 1;
-}
-
-// Define a dummy template to workaround a compile error if __popcnt64() is not defined.
-//
-// If __popcnt64() is defined in <intrin.h> it will be choosen first due to
-// C++ overload rules that always prefer a function to a template with the same name.
-// If not, we avoid a compile error and because cpu_has_popcnt() should return false,
-// our templetized __popcnt64() is never called anyway.
-template<typename T> unsigned __popcnt64(T) { return 0; } // Is never called
-
-#define POPCNT_INTRINSIC(x) __popcnt64(x)
-
-#elif defined(__INTEL_COMPILER) && defined(IS_64BIT) && defined(USE_POPCNT) // Intel compiler
-
-#include <nmmintrin.h>
-
-inline bool cpu_has_popcnt() {
-
- int CPUInfo[4] = {-1};
- __cpuid(CPUInfo, 0x00000001);
- return (CPUInfo[2] >> 23) & 1;
-}
-
-// See comment of __popcnt64<>() few lines above for an explanation.
-template<typename T> unsigned _mm_popcnt_u64(T) { return 0; } // Is never called
+enum BitCountType {
+ CNT64,
+ CNT64_MAX15,
+ CNT32,
+ CNT32_MAX15,
+ CNT_POPCNT
+};
-#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
-
-#else // Safe fallback for unsupported compilers or when USE_POPCNT is disabled
-
-inline bool cpu_has_popcnt() { return false; }
-
-#define POPCNT_INTRINSIC(x) 0
-
-#endif // cpu_has_popcnt() and POPCNT_INTRINSIC() definitions
-
-
-/// Software implementation of bit count functions
-
-#if defined(IS_64BIT)
-
-inline int count_1s(Bitboard b) {
+/// count_1s() counts the number of nonzero bits in a bitboard.
+/// We have different optimized versions according if platform
+/// is 32 or 64 bits, and to the maximum number of nonzero bits.
+/// We also support hardware popcnt instruction. See Readme.txt
+/// on how to pgo compile with popcnt support.
+template<BitCountType> inline int count_1s(Bitboard);
+
+template<>
+inline int count_1s<CNT64>(Bitboard b) {
b -= ((b>>1) & 0x5555555555555555ULL);
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
return int(b >> 56);
}
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int count_1s<CNT64_MAX15>(Bitboard b) {
b -= (b>>1) & 0x5555555555555555ULL;
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b *= 0x1111111111111111ULL;
return int(b >> 60);
}
-#else // if !defined(IS_64BIT)
-
-inline int count_1s(Bitboard b) {
+template<>
+inline int count_1s<CNT32>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
return int(v >> 24);
}
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int count_1s<CNT32_MAX15>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
return int(v >> 28);
}
-#endif // BITCOUNT
-
-
-/// count_1s() counts the number of nonzero bits in a bitboard.
-/// If template parameter is true an intrinsic is called, otherwise
-/// we fallback on a software implementation.
-
-template<bool UseIntrinsic>
-inline int count_1s(Bitboard b) {
-
- return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s(b);
+template<>
+inline int count_1s<CNT_POPCNT>(Bitboard b) {
+#if !defined(USE_POPCNT)
+ return int(b != 0); // Avoid 'b not used' warning
+#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
+ return _mm_popcnt_u64(b);
+#elif defined(_MSC_VER)
+ return __popcnt64(b);
+#elif defined(__GNUC__)
+ unsigned long ret;
+ __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
+ return ret;
+#endif
}
-template<bool UseIntrinsic>
-inline int count_1s_max_15(Bitboard b) {
- return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s_max_15(b);
+/// cpu_has_popcnt() detects support for popcnt instruction at runtime
+inline bool cpu_has_popcnt() {
+
+ int CPUInfo[4] = {-1};
+ __cpuid(CPUInfo, 0x00000001);
+ return (CPUInfo[2] >> 23) & 1;
}
-// Global constant initialized at startup that is set to true if
-// CPU on which application runs supports POPCNT intrinsic. Unless
-// USE_POPCNT is not defined.
+/// CpuHasPOPCNT is a global constant initialized at startup that
+/// is set to true if CPU on which application runs supports popcnt
+/// hardware instruction. Unless USE_POPCNT is not defined.
+#if defined(USE_POPCNT)
const bool CpuHasPOPCNT = cpu_has_popcnt();
+#else
+const bool CpuHasPOPCNT = false;
+#endif
-// Global constant used to print info about the use of 64 optimized
-// functions to verify that a 64 bit compile has been correctly built.
+/// CpuIs64Bit is a global constant initialized at compile time that
+/// is set to true if CPU on which application runs is a 64 bits.
#if defined(IS_64BIT)
-const bool CpuHas64BitPath = true;
+const bool CpuIs64Bit = true;
#else
-const bool CpuHas64BitPath = false;
+const bool CpuIs64Bit = false;
#endif
#endif // !defined(BITCOUNT_H_INCLUDED)
projects / stockfish / blobdiff