HCha/Stockfish
1
0
Fork 0
mirror of https://github.com/HChaZZY/Stockfish.git synced 2025-12-25 19:46:55 +08:00
Code Issues Packages Projects Releases Wiki Activity

Store additional bits for fullmove clock and 50 more rule halfmove clock at the end of the bit stream. This change keeps backwards compatibility.

Browse Source
This commit is contained in:
Tomasz Sobczyk
2020-10-11 12:01:23 +02:00
committed by nodchip
parent de20887e11
commit 7d62b3f799
2 changed files with 86 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files

76
src/learn/sfen_packer.cpp
View File

@@ -113,43 +113,24 @@ namespace Learner {
// Huffman coding
// * is simplified from mini encoding to make conversion easier.
//
// 1 box on the board (other than NO_PIECE) = 2 to 6 bits (+ 1-bit flag + 1-bit forward and backward)
// 1 piece of hand piece = 1-5bit (+ 1-bit flag + 1bit ahead and behind)
//
// empty xxxxx0 + 0 (none)
// step xxxx01 + 2 xxxx0 + 2
// incense xx0011 + 2 xx001 + 2
// Katsura xx1011 + 2 xx101 + 2
// silver xx0111 + 2 xx011 + 2
// Gold x01111 + 1 x0111 + 1 // Gold is valid and has no flags.
// corner 011111 + 2 01111 + 2
// Fly 111111 + 2 11111 + 2
//
// Assuming all pieces are on the board,
// Sky 81-40 pieces = 41 boxes = 41bit
// Walk 4bit*18 pieces = 72bit
// Incense 6bit*4 pieces = 24bit
// Katsura 6bit*4 pieces = 24bit
// Silver 6bit*4 pieces = 24bit
// Gold 6bit* 4 pieces = 24bit
// corner 8bit* 2 pieces = 16bit
// Fly 8bit* 2 pieces = 16bit
// -------
// 241bit + 1bit (turn) + 7bit × 2 (King's position after) = 256bit
//
// When the piece on the board moves to the hand piece, the piece on the board becomes empty, so the box on the board can be expressed with 1 bit,
// Since the hand piece can be expressed by 1 bit less than the piece on the board, the total number of bits does not change in the end.
// Therefore, in this expression, any aspect can be expressed by this bit number.
// It is a hand piece and no flag is required, but if you include this, the bit number of the piece on the board will be -1
// Since the total number of bits can be fixed, we will include this as well.
// Huffman Encoding
//
// Empty xxxxxxx0
// Pawn xxxxx001 + 1 bit (Side to move)
// Knight xxxxx011 + 1 bit (Side to move)
// Bishop xxxxx101 + 1 bit (Side to move)
// Rook xxxxx111 + 1 bit (Side to move)
// Pawn xxxxx001 + 1 bit (Color)
// Knight xxxxx011 + 1 bit (Color)
// Bishop xxxxx101 + 1 bit (Color)
// Rook xxxxx111 + 1 bit (Color)
// Queen xxxx1001 + 1 bit (Color)
//
// Worst case:
// - 32 empty squares 32 bits
// - 30 pieces 150 bits
// - 2 kings 12 bits
// - castling rights 4 bits
// - ep square 7 bits
// - rule50 7 bits
// - game ply 16 bits
// - TOTAL 228 bits < 256 bits
struct HuffmanedPiece
{
@@ -212,7 +193,18 @@ namespace Learner {
stream.write_n_bit(pos.state()->rule50, 6);
stream.write_n_bit(1 + (pos.game_ply()-(pos.side_to_move() == BLACK)) / 2, 8);
const int fm = 1 + (pos.game_ply()-(pos.side_to_move() == BLACK)) / 2;
stream.write_n_bit(fm, 8);
// Write high bits of half move. This is a fix for the
// limited range of half move counter.
// This is backwards compatibile.
stream.write_n_bit(fm >> 8, 8);
// Write the highest bit of rule50 at the end. This is a backwards
// compatibile fix for rule50 having only 6 bits stored.
// This bit is just ignored by the old parsers.
stream.write_n_bit(pos.state()->rule50 >> 6, 1);
assert(stream.get_cursor() <= 256);
}
@@ -355,10 +347,20 @@ namespace Learner {
}
// Halfmove clock
pos.st->rule50 = static_cast<Square>(stream.read_n_bit(6));
pos.st->rule50 = stream.read_n_bit(6);
// Fullmove number
pos.gamePly = static_cast<Square>(stream.read_n_bit(8));
pos.gamePly = stream.read_n_bit(8);
// Read the highest bit of rule50. This was added as a fix for rule50
// counter having only 6 bits stored.
// In older entries this will just be a zero bit.
pos.gamePly |= stream.read_n_bit(8) << 8;
// Read the highest bit of rule50. This was added as a fix for rule50
// counter having only 6 bits stored.
// In older entries this will just be a zero bit.
pos.st->rule50 |= stream.read_n_bit(1) << 6;
// Convert from fullmove starting from 1 to gamePly starting from 0,
// handle also common incorrect FEN with fullmove = 0.