X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitcount.h;h=9d25a5e5c1b4d7b7bd19c0bd0cd60234209741a5;hp=43895180c1e9ae7566e16e3f35f29b93e00e18eb;hb=161c6b025e763d6bcc8339a614be312f2b173437;hpb=92bada1a32c7ebd5f5b4438bd85bb003d20bd046

diff --git a/src/bitcount.h b/src/bitcount.h
index 43895180..9d25a5e5 100644
--- a/src/bitcount.h
+++ b/src/bitcount.h
@@ -1,7 +1,7 @@
 /*
   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) 2008-2012 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
@@ -18,65 +18,32 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-
 #if !defined(BITCOUNT_H_INCLUDED)
 #define BITCOUNT_H_INCLUDED
 
+#include <cassert>
 #include "types.h"
 
-// Select type of intrinsic bit count instruction to use, see
-// README.txt on how to pgo compile with POPCNT support.
-
-#if defined(__INTEL_COMPILER) && defined(USE_POPCNT) // Intel compiler
-
-inline bool cpu_has_popcnt() {
-
-  int CPUInfo[4] = {-1};
-  __cpuid(CPUInfo, 0x00000001);
-  return (CPUInfo[2] >> 23) & 1;
-}
-
-#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
-
-#elif defined(_MSC_VER) && defined(USE_POPCNT) // Microsoft compiler
+enum BitCountType {
+  CNT_64,
+  CNT_64_MAX15,
+  CNT_32,
+  CNT_32_MAX15,
+  CNT_HW_POPCNT
+};
 
-inline bool cpu_has_popcnt() {
-
-  int CPUInfo[4] = {-1};
-  __cpuid(CPUInfo, 0x00000001);
-  return (CPUInfo[2] >> 23) & 1;
-}
-
-#define POPCNT_INTRINSIC(x) (int)__popcnt64(x)
-
-#elif defined(__GNUC__) && defined(USE_POPCNT) // Gcc compiler
-
-inline bool cpu_has_popcnt() {
-
-  unsigned int eax, ebx, ecx, edx;
-  __cpuid(1, &eax, &ebx, &ecx, &edx);
-  return (ecx >> 23) & 1;
-}
+/// Determine at compile time the best popcount<> specialization according if
+/// platform is 32 or 64 bits, to the maximum number of nonzero bits to count or
+/// use hardware popcnt instruction when available.
+const BitCountType Full  = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64 : CNT_32;
+const BitCountType Max15 = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64_MAX15 : CNT_32_MAX15;
 
-#define POPCNT_INTRINSIC(x) ({ \
-   unsigned long __ret; \
-   __asm__("popcnt %1, %0" : "=r" (__ret) : "r" (x)); \
-   __ret; })
 
-#else // Safe fallback for unsupported compilers or when USE_POPCNT is disabled
+/// popcount() counts the number of nonzero bits in a bitboard
+template<BitCountType> inline int popcount(Bitboard);
 
-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) {
+template<>
+inline int popcount<CNT_64>(Bitboard b) {
   b -= ((b>>1) & 0x5555555555555555ULL);
   b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
   b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
@@ -84,16 +51,16 @@ inline int count_1s(Bitboard b) {
   return int(b >> 56);
 }
 
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int popcount<CNT_64_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 popcount<CNT_32>(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
   w -= (w >> 1) & 0x55555555;
@@ -105,7 +72,8 @@ inline int count_1s(Bitboard b) {
   return int(v >> 24);
 }
 
-inline int count_1s_max_15(Bitboard b) {
+template<>
+inline int popcount<CNT_32_MAX15>(Bitboard b) {
   unsigned w = unsigned(b >> 32), v = unsigned(b);
   v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
   w -= (w >> 1) & 0x55555555;
@@ -116,38 +84,29 @@ inline int count_1s_max_15(Bitboard b) {
   return int(v >> 28);
 }
 
-#endif // BITCOUNT
+template<>
+inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
 
+#if !defined(USE_POPCNT)
 
-/// 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.
+  assert(false);
+  return int(b != 0); // Avoid 'b not used' warning
 
-template<bool UseIntrinsic>
-inline int count_1s(Bitboard b) {
+#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
 
-  return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s(b);
-}
-
-template<bool UseIntrinsic>
-inline int count_1s_max_15(Bitboard b) {
+  return _mm_popcnt_u64(b);
 
-  return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s_max_15(b);
-}
+#elif defined(_MSC_VER)
 
+  return (int)__popcnt64(b);
 
-// 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.
-const bool CpuHasPOPCNT = cpu_has_popcnt();
+#else
 
+  unsigned long ret;
+  __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
+  return ret;
 
-// Global constant used to print info about the use of 64 optimized
-// functions to verify that a 64 bit compile has been correctly built.
-#if defined(IS_64BIT)
-const bool CpuHas64BitPath = true;
-#else
-const bool CpuHas64BitPath = false;
 #endif
+}
 
 #endif // !defined(BITCOUNT_H_INCLUDED)