From 36a4ff5676ef0cfa0e75012204894ff1ebac1a17 Mon Sep 17 00:00:00 2001
From: Quinten Kock <quintenkock@gmail.com>
Date: Thu, 18 Jun 2020 20:47:11 +0200
Subject: [PATCH] Better board_init, implement basic castling in unmake

---
 Board.h | 66 +++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 45 insertions(+), 21 deletions(-)

diff --git a/Board.h b/Board.h
index 05592de..a685923 100644
--- a/Board.h
+++ b/Board.h
@@ -16,21 +16,11 @@
 	B_ROOK, B_KNGT, B_BSHP, B_QUEN, B_KING, B_BSHP, B_KNGT, B_ROOK, 0, 0, 0, 0, 0, 0, 0, 0, \
 };
 
-
-byte field[128];
-const byte field_default_value[] PROGMEM = BOARD_DEFAULT_VALUE;
-
-void board_init() {
-	for(int i = 0; i < 128; i++) {
-		field[i] = pgm_read_byte_near(field_default_value + i);
-	}
-}
-
 // 0x88-fill definitions
 #define PTR_SIDE_AND_CASTLERIGHT 0x08 //byte (1=side, 2,4=white castle, 8,16=black)
 // CAN FILL 0x09
 #define PTR_W_KING 0x0A // byte (points to index or maybe 64-arr index)
-// const byte PTR_B_KING = 0x0B; (PTR_W_KING | COLOR or PTR_W_KING + COLOR)
+#define PTR_B_KING 0x0B // (PTR_W_KING | COLOR or PTR_W_KING + COLOR)
 #define PTR_ZOBRIST 0x0C // 4 bytes
 // 0x0D
 // 0x0E
@@ -42,11 +32,28 @@ void board_init() {
 
 #define PTR_UNMOVE_START 0x28
 #define PTR_UNMOVE_LAST 0x7F
+
+byte field[128];
 byte PTR_UNMOVE = PTR_UNMOVE_START;
 
+const byte field_default_value[] PROGMEM = BOARD_DEFAULT_VALUE;
+
+void board_init() {
+	for(int i = 0; i < 128; i++) {
+		field[i] = pgm_read_byte_near(field_default_value + i);
+	}
+	field[PTR_SIDE_AND_CASTLERIGHT] = 0b11110; // all castle rights allowed, white to move
+	field[PTR_W_KING] = 0x04; // e1
+	field[PTR_B_KING] = 0x74; // e8
+	long* zob = (long*)&field[PTR_ZOBRIST];
+	*zob = 0xDEADBEEF;
+}
+
+
+
 struct Unmove {
 	byte sq_from;	// 0b(1unused)(3rank)(1unused)(3file)
-	byte sq_to;	// 0b(1promoted?)(3rank)(1unused)(3file)
+	byte sq_to;	// 0b(1promoted?)(3rank)(1ep_capture?)(3file)
 	byte captured;	// 0b(4enpassantinfo)(1color)(3piecetype)
 	byte revmov;	// 8bit integer
 };
@@ -117,7 +124,6 @@ void print() {
 }
 
 void make(Move m) {
-	// TODO handle revmov clock
 	// TODO zobrist?
 
 	// fill unmove struct with basic data
@@ -136,7 +142,7 @@ void make(Move m) {
 	}
 
 	// Calculate the move 'amount' (unique signature for dx,dy)
-	int sq_diff = (int)m.sq_from - (int)m.sq_to;
+	int sq_diff = (int)m.sq_to - (int)m.sq_from;
 	int sq_diff_abs = abs(sq_diff);
 
 
@@ -158,17 +164,18 @@ void make(Move m) {
 	// Handle castling rights
 	// We are doing the simple way:
 	// unset it any time a move is made from the original position.
-	if(m.sq_from == 0x00)
+	// TODO handle castle rights and unmake
+	if(m.sq_from == 0x00) // white queenside rook
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b00010;
-	if(m.sq_from == 0x07)
+	if(m.sq_from == 0x07) // white kingside rook
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b00100;
-	if(m.sq_from == 0x04)
+	if(m.sq_from == 0x04) // white king
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b00110;
-	if(m.sq_from == 0x70)
+	if(m.sq_from == 0x70) // black queenside rook
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b01000;
-	if(m.sq_from == 0x77)
+	if(m.sq_from == 0x77) // black kingside rook
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b10000;
-	if(m.sq_from == 0x74)
+	if(m.sq_from == 0x74) // black king
 		field[PTR_SIDE_AND_CASTLERIGHT] &= ~0b11000;
 
 
@@ -192,7 +199,7 @@ void make(Move m) {
 	// handle enpassant setup (double pawn move)
 	if(
 		piece_type == W_PAWN &&
-		(sq_diff_abs == 32)
+		sq_diff_abs == 32
 	) {
 		// we are doing a pawn double-move.
 		// therefore, it allows enpassant in the next move.
@@ -244,6 +251,23 @@ void unmake() {
 		// also undo the regular move
 		field[u.sq_from] = field[sq_to];
 	}
+	// TODO handle castling rights
+
+	int sq_diff = (int)sq_to - (int)u.sq_from;
+	int sq_diff_abs = abs(sq_diff);
+	if((field[u.sq_from] & 0x7) == W_KING && sq_diff_abs == 2) {
+		// we castled
+		byte castle_source = 0x70*!black_moving();
+		if(sq_diff == 2) {
+			castle_source += 0x7;
+		}
+		byte castle_target = u.sq_from + (sq_diff/2);
+		// move rook back to original position
+		field[castle_source] = field[castle_target];
+		// and clear where it was put
+		field[castle_target] = P_EMPTY;
+	}
+
 
 	field[sq_to] = u.captured & 0b1111;