kate/BadFish
1
0
Fork 0
mirror of https://github.com/sockspls/badfish synced 2025-04-30 16:53:09 +00:00
Code Issues Releases Wiki Activity

Use double rotate for magic generation

Browse source 
Allow to choose among 4096 instances of pseudo-random
sequences instead of the previous 64 so the probability
to find a better sequence increases and actually we have
a much better 64 bit case and we can also use the 64 bit
version of pick_magic() also for 32 bits and althoug sub
optimal, because now we can have more choices results are
even slightly better also for 32 bit.

Use also a faster submask().

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2011-06-09 18:09:19 +01:00
parent e0215f3222
commit b414fc0dfd
1 changed files with 23 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
src/bitboard.cpp
View file

@ -255,13 +255,20 @@ namespace {
Bitboard submask(Bitboard mask, int key) { Bitboard submask(Bitboard mask, int key) {
Bitboard subMask = 0; Bitboard b, subMask = 0;
int bitNum = -1; int bitProbe = 1;
// Extract an unique submask out of a mask according to the given key // Extract an unique submask out of a mask according to the given key
for (Square s = SQ_A1; s <= SQ_H8; s++) while (mask)
if (bit_is_set(mask, s) && bit_is_set(key, Square(++bitNum))) {
set_bit(&subMask, s); b = mask & -mask;
mask ^= b;
if (key & bitProbe)
subMask |= b;
bitProbe <<= 1;
}
return subMask; return subMask;
} }
@ -289,20 +296,21 @@ namespace {
return attacks; return attacks;
} }
template<bool Is64>
Bitboard pick_magic(Bitboard mask, RKISS& rk, int booster) { Bitboard pick_magic(Bitboard mask, RKISS& rk, int booster) {
Bitboard magic; Bitboard magic;
// Advance PRNG state of a quantity known to be the optimal to // Values s1 and s2 are used to rotate the candidate magic of
// quickly retrieve all the magics. // a quantity known to be the optimal to quickly find the magics.
for (int i = 0; i < booster; i++) int s1 = booster & 63, s2 = (booster >> 6) & 63;
rk.rand<Bitboard>();
while (true) while (true)
{ {
magic = rk.rand<Bitboard>() & rk.rand<Bitboard>(); magic = rk.rand<Bitboard>();
magic &= Is64 ? rk.rand<Bitboard>() : (rk.rand<Bitboard>() | rk.rand<Bitboard>()); magic = (magic >> s1) | (magic << (64 - s1));
magic &= rk.rand<Bitboard>();
magic = (magic >> s2) | (magic << (64 - s2));
magic &= rk.rand<Bitboard>();
if (BitCount8Bit[(mask * magic) >> 56] >= 6) if (BitCount8Bit[(mask * magic) >> 56] >= 6)
return magic; return magic;
@ -312,8 +320,8 @@ namespace {
void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[], void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[],
Bitboard mask[], int shift[], Square delta[]) { Bitboard mask[], int shift[], Square delta[]) {
const int MagicBoosters[][8] = { { 55, 11, 17, 2, 39, 3, 31, 44 }, const int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
{ 26, 21, 21, 32, 31, 9, 5, 11 } }; { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
RKISS rk; RKISS rk;
Bitboard occupancy[4096], reference[4096], excluded; Bitboard occupancy[4096], reference[4096], excluded;
int key, maxKey, index, booster, offset = 0; int key, maxKey, index, booster, offset = 0;
@ -339,7 +347,7 @@ namespace {
// Then find a possible magic and the corresponding attacks // Then find a possible magic and the corresponding attacks
do { do {
magic[s] = pick_magic<CpuIs64Bit>(mask[s], rk, booster); magic[s] = pick_magic(mask[s], rk, booster);
memset(attack[s], 0, maxKey * sizeof(Bitboard)); memset(attack[s], 0, maxKey * sizeof(Bitboard));
for (key = 0; key < maxKey; key++) for (key = 0; key < maxKey; key++)