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Code Issues Releases Wiki Activity

Retire bitScanReverse32()

Browse source 
Use log() instead because we are not in speed
critical paths.

Also a bit of renaming and code shuffle while there.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-06-01 21:28:45 +01:00
parent 50e094ef8d
commit 5212995563
3 changed files with 45 additions and 79 deletions
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33
src/bitboard.cpp
View file

@ -373,39 +373,6 @@ Square pop_1st_bit(Bitboard* bb) {
#endif
// Optimized bitScanReverse32() implementation by Pascal Georges. Note
// that first bit is 1, this allow to differentiate between 0 and 1.
static CACHE_LINE_ALIGNMENT
const char MsbTable[256] = {
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8
};
int bitScanReverse32(uint32_t b)
{
int result = 0;
if (b > 0xFFFF)
{
b >>= 16;
result += 16;
}
if (b > 0xFF)
{
b >>= 8;
result += 8;
}
return result + MsbTable[b];
}
namespace {

1
src/bitboard.h
View file

@ -342,7 +342,6 @@ extern Square pop_1st_bit(Bitboard* b);
extern void print_bitboard(Bitboard b);
extern void init_bitboards();
extern int bitScanReverse32(uint32_t b);
#endif // !defined(BITBOARD_H_INCLUDED)

90
src/search.cpp
View file

@ -337,6 +337,51 @@ void exit_threads() { TM.exit_threads(); }
int64_t nodes_searched() { return TM.nodes_searched(); }
/// init_search() is called during startup. It initializes various lookup tables
void init_search() {
int d; // depth (OnePly == 2)
int hd; // half depth (OnePly == 1)
int mc; // moveCount
// Init reductions array
for (hd = 1; hd < 64; hd++) for (mc = 1; mc < 64; mc++)
{
double pvRed = log(double(hd)) * log(double(mc)) / 3.0;
double nonPVRed = log(double(hd)) * log(double(mc)) / 1.5;
ReductionMatrix[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
ReductionMatrix[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
}
// Init futility margins array
for (d = 0; d < 16; d++) for (mc = 0; mc < 64; mc++)
FutilityMarginsMatrix[d][mc] = 112 * int(log(double(d * d) / 2) / log(2.0) + 1) - 8 * mc + 45;
// Init futility move count array
for (d = 0; d < 32; d++)
FutilityMoveCountArray[d] = 3 + (1 << (3 * d / 8));
}
// SearchStack::init() initializes a search stack. Used at the beginning of a
// new search from the root.
void SearchStack::init(int ply) {
pv[ply] = pv[ply + 1] = MOVE_NONE;
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
eval = VALUE_NONE;
}
void SearchStack::initKillers() {
mateKiller = MOVE_NONE;
for (int i = 0; i < KILLER_MAX; i++)
killers[i] = MOVE_NONE;
}
/// perft() is our utility to verify move generation is bug free. All the legal
/// moves up to given depth are generated and counted and the sum returned.
@ -549,51 +594,6 @@ bool think(const Position& pos, bool infinite, bool ponder, int side_to_move,
}
/// init_search() is called during startup. It initializes various lookup tables
void init_search() {
// Init our reduction lookup tables
for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
for (int j = 1; j < 64; j++) // j == moveNumber
{
double pvRed = log(double(i)) * log(double(j)) / 3.0;
double nonPVRed = log(double(i)) * log(double(j)) / 1.5;
ReductionMatrix[PV][i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
ReductionMatrix[NonPV][i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
}
// Init futility margins array
for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)
for (int j = 0; j < 64; j++) // j == moveNumber
{
// FIXME: test using log instead of BSR
FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j + 45;
}
// Init futility move count array
for (int i = 0; i < 32; i++) // i == depth (OnePly = 2)
FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8));
}
// SearchStack::init() initializes a search stack. Used at the beginning of a
// new search from the root.
void SearchStack::init(int ply) {
pv[ply] = pv[ply + 1] = MOVE_NONE;
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
eval = VALUE_NONE;
}
void SearchStack::initKillers() {
mateKiller = MOVE_NONE;
for (int i = 0; i < KILLER_MAX; i++)
killers[i] = MOVE_NONE;
}
namespace {
// id_loop() is the main iterative deepening loop. It calls root_search