Implement enpassant

ArduChess.ino

@@ -10,30 +10,43 @@ void setup() {
 	// put your setup code here, to run once:
 	Serial.begin(9600);
 
-	char value;
-	while(Serial.available() == 0) {
-		delay(100);
-	}
-	value = Serial.read();
+	//char value;
+	//while(Serial.available() == 0) {
+	//	delay(100);
+	//}
+	//value = Serial.read();
+
+	//b.field[0x31] = char_to_piece(value);
+
+	//Serial.println(F("hello"));
+	//delay(1000);
+	//Serial.println(b.get_zobrist());
+	//Serial.println(sizeof(b));
+
+	//Move m = {0x14, 0x34, P_EMPTY};
+	//Serial.println(F("Initial board"));
+	//b.print();
+	//b.make(m);
+	//Serial.println(F("Board after e2e4"));
+	//b.print();
+	//b.unmake();
+	//Serial.println(F("Board after unmake"));
+	//b.print();
+	//delay(1000);
+	Serial.println(F("hello"));
+
+	b = Board();
+	b.make({0x14, 0x34, P_EMPTY});
+	b.make({0x64, 0x54, P_EMPTY});
+	b.make({0x34, 0x44, P_EMPTY});
+	b.make({0x63, 0x43, P_EMPTY});
+	b.print();
+	b.make({0x44, 0x53, P_EMPTY});
+	b.print();
+
 
-	b.field[0x32] = char_to_piece(value);
 }
 
 void loop() {
 	// put your main code here, to run repeatedly:
-	Serial.println(F("hello"));
-	delay(1000);
-	Serial.println(b.get_zobrist());
-	Serial.println(sizeof(b));
-
-	Move m = {0x14, 0x34, P_EMPTY};
-	Serial.println(F("Initial board"));
-	b.print();
-	b.make(m);
-	Serial.println(F("Board after e2e4"));
-	b.print();
-	b.unmake();
-	Serial.println(F("Board after unmake"));
-	b.print();
-	delay(1000);
 }

Board.h

@@ -6,10 +6,11 @@
 #include "Move.h"
 
 struct Unmove {
-	byte sq_from;
-	byte sq_to;
-	byte captured;
+	byte sq_from;	// 0b(1unused)(3rank)(1unused)(3file)
+	byte sq_to;	// 0b(1promoted?)(3rank)(1unused)(3file)
+	byte captured;	// 0b(4unused)(1color)(3piecetype)
 	byte enpassant;
+	byte revmov;
 };
 
 class Board {
@@ -30,6 +31,10 @@ class Board {
 		return *addr;
 	}
 
+	void reset_unmake_stack() {
+		PTR_UNMOVE = PTR_UNMOVE_START;
+	}
+
 	byte field[128] = {
 		W_ROOK, W_KNGT, W_BSHP, W_QUEN, W_KING, W_BSHP, W_KNGT, W_ROOK, 0, 0, 0, 0, 0, 0, 0, 0,
 		W_PAWN, W_PAWN, W_PAWN, W_PAWN, W_PAWN, W_PAWN, W_PAWN, W_PAWN, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -86,25 +91,68 @@ void Board::print() {
 }
 
 void Board::make(Move m) {
+	// fill unmove struct with basic data
 	Unmove u;
 	u.captured = field[m.sq_to];
 	u.sq_from = m.sq_from;
 	u.sq_to = m.sq_to;
 
-	byte new_val = m.pc_prom & 0b1111;
-	if(new_val != P_EMPTY) {
-		u.sq_to |= 0x80;
-	} else {
-		new_val = field[m.sq_from];
-	}
-	field[m.sq_to] = field[m.sq_from];
-	field[m.sq_from] = P_EMPTY;
-
 	// TODO handle castling
 	// TODO handle castling rights
 	// TODO handle revmov clock
-	// TODO handle enpassant
+	// TODO zobrist
 
+	// TODO: test enpassant code
+
+	// handle enpassant capture
+	if(field[PTR_ENPASSANT] && (field[m.sq_from] & 0b111) == W_PAWN) {
+		// en-passant capture is allowed.
+		// we are also doing a pawn move
+		// do further checks to see if we should remove the EP-pawn.
+		if(
+			(m.sq_to & 0x7) == (field[PTR_ENPASSANT] & 0x7) &&
+			(m.sq_to & 0x70) == (0x50 - 0x30*black_moving())
+		) {
+			// we are also going to the correct square to do EP.
+			// therefore, delete the EP-vurnerable pawn
+			byte ep_field = m.sq_to - 16 + 32*black_moving();
+			field[ep_field] = P_EMPTY;
+		}
+	}
+
+	// Store the current enpassant situation
+	u.enpassant = field[PTR_ENPASSANT];
+
+	// handle enpassant setup (double pawn move)
+	// Calculate the move 'amount'
+	int sq_diff = (int)m.sq_from - (int)m.sq_to;
+	if(
+		(field[m.sq_from] & 0b111) == W_PAWN &&
+		(sq_diff == 32 || sq_diff == -32)
+	) {
+		// we are doing a pawn double-move.
+		// therefore, it allows enpassant in the next move.
+		field[PTR_ENPASSANT] = 0b1000 | (m.sq_from & 0x7);
+	} else {
+		// no enpassant in the next turn.
+		field[PTR_ENPASSANT] = 0;
+	}
+
+	// are we promoting?
+	byte new_val = m.pc_prom & 0b1111;
+	if(new_val != P_EMPTY) {
+		// promoting; indicate this in the sq_to byte in unmove.
+		u.sq_to |= 0x80;
+	} else {
+		// not promoting; so keep the same piece type
+		new_val = field[m.sq_from];
+	}
+	// copy (and possibly promote) our piece.
+	field[m.sq_to] = new_val;
+	// then delete the original copy.
+	field[m.sq_from] = P_EMPTY;
+
+	// Switch sides
 	field[PTR_SIDE_AND_CASTLERIGHT] ^= 0x01;
 
 	store_unmove(u);

Move.h

@@ -4,9 +4,9 @@
 #include "Types.h"
 
 struct Move {
-	byte sq_from;
-	byte sq_to;
-	Piece pc_prom;
+	byte sq_from;	// 0x88
+	byte sq_to;	// 0x88
+	Piece pc_prom;	// 0b(4unused)(1color)(3type)
 };
 
 //Move move_from_str(char* s) {