bpaul-chess

commit b6f7fbad7dea4cf71ad7d8b00d6842b63f38bfd0
parent 87e142b2ea66019107aa1f58db1aac2142c7ee44
Author: benjamin paul <bpaul@bpaul.xyz>
Date:   Sat, 23 Oct 2021 21:17:47 +1000

Added most of the parsefen function, excluding the fifty-move rule and the turn count

Diffstat:
M
Makefile
 | 
2
+-
M
src/pos.c
 | 
110
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------
M
src/pos.h
 | 
2
+-

3 files changed, 94 insertions(+), 20 deletions(-)
diff --git a/Makefile b/Makefile
@@ -5,7 +5,7 @@ NAME	= bpaul-chess
 CC		= cc
 CFLAGS	= -march=native -O3 -flto
 
-OBJS	= src/main.o src/bb.o src/gen.c
+OBJS	= src/main.o src/bb.o src/gen.o src/pos.o
 
 all: $(NAME)
 
diff --git a/src/pos.c b/src/pos.c
@@ -1,3 +1,6 @@
+#include <assert.h>
+#include <stdbool.h>
+
 #include "bb.h"
 #include "pos.h"
 
@@ -11,10 +14,15 @@ piece(unsigned char p) {
 	return p & 7;
 }
 
+unsigned char
+square(unsigned char r, unsigned char c) {
+	return r*8 + c;
+}
+
 void
-setpiece(pos *p, unsigned char piece, unsigned char sq) {
-	setbit(p->sides[side(piece)], sq);
-	setbit(p->pieces[piece(piece)], sq);
+setpiece(pos *p, unsigned char pc, unsigned char sq) {
+	setbit(&p->sides[side(pc)], sq);
+	setbit(&p->pieces[piece(pc)], sq);
 }
 
 void
@@ -22,24 +30,27 @@ parsefen(pos *p, char *fen) {
 	char phase, sq;
 
 	phase = 0;
-	sq = 63;
+	sq = 56;
 
 	while (*fen) {
+		/* Piece placement */
 		if (phase == 0) {
 			switch (*fen) {
-				case 'P': setpiece(p, wP, sq); break;
-				case 'N': setpiece(p, wN, sq); break;
-				case 'B': setpiece(p, wB, sq); break;
-				case 'R': setpiece(p, wR, sq); break;
-				case 'Q': setpiece(p, wQ, sq); break;
-				case 'K': setpiece(p, wK, sq); break;
-				case 'p': setpiece(p, bP, sq); break;
-				case 'n': setpiece(p, bN, sq); break;
-				case 'b': setpiece(p, bB, sq); break;
-				case 'r': setpiece(p, bR, sq); break;
-				case 'q': setpiece(p, bQ, sq); break;
-				case 'k': setpiece(p, bK, sq); break;
+				/* Place a piece on the current square */
+				case 'P': setpiece(p, wP, sq); sq++; break;
+				case 'N': setpiece(p, wN, sq); sq++; break;
+				case 'B': setpiece(p, wB, sq); sq++; break;
+				case 'R': setpiece(p, wR, sq); sq++; break;
+				case 'Q': setpiece(p, wQ, sq); sq++; break;
+				case 'K': setpiece(p, wK, sq); sq++; break;
+				case 'p': setpiece(p, bP, sq); sq++; break;
+				case 'n': setpiece(p, bN, sq); sq++; break;
+				case 'b': setpiece(p, bB, sq); sq++; break;
+				case 'r': setpiece(p, bR, sq); sq++; break;
+				case 'q': setpiece(p, bQ, sq); sq++; break;
+				case 'k': setpiece(p, bK, sq); sq++; break;
 
+				/* Move over to the rightby the number specified */
 				case '1':
 				case '2':
 				case '3':
@@ -48,13 +59,76 @@ parsefen(pos *p, char *fen) {
 				case '6':
 				case '7':
 				case '8':
-					sq -= *fen - '0';
+					/* In case you were unaware, subtracting '0' from an ascii
+					 * character which is a number gives the integer value of
+					 * the number. For example, '8' - '0' = 8. */
+					sq += *fen - '0';
 
 				case '/':
-					sq = (sq & ~7) - 1;
+					/* This should only occur after we have moved past the last
+					 * column in the current row. We will be placed in the
+					 * first column of the row above the current one, but we
+					 * would want to be in the row below us, so we get shifted
+					 * by 2 rows downwards. */
+					assert(sq % 8 == 0);
+					sq -= 16;
+
+				default:
+					/* There was an error in the fen */
+					assert(0);
+			}
+
+			if (sq < 0) { phase++; fen += 2; }
+		}
+
+		/* Turn */
+		if (phase == 1) {
+			fen++;
+			if (*fen == 'w') {
+				p->turn = WHITE;
+			} else {
+				p->turn = BLACK;
+			}
+			phase++;
+			fen += 2;
+		}
+
+		/* Castling rights */
+		if (phase == 2 && *fen != ' ') {
+			switch (*fen) {
+				/* The castling rights value is a bitset, i.e. each of the
+				 * first four bits represent a different castling right. */
+				case 'K': p->castle |= 8; break;
+				case 'Q': p->castle |= 4; break;
+				case 'k': p->castle |= 2; break;
+				case 'q': p->castle |= 1; break;
+
+				/* If it is not one of these characters there is
+				 * something wrong with the fen */
+				default: assert(0);
 			}
+		} else if (phase == 2) phase++;
+
+		/* En passant */
+		if (phase == 3) {
+			fen++;
+			/* Extract the column and row */
+			char c = *fen - 'a';
+			fen++;
+			char r = *fen - '1';
+			/* Calculate the square based on the column and row */
+			p->enpas = square(r, c);
+			fen+=2;
 		}
 
+		/* I cant be bothered to do the rest right now */
+
+
+
+		/* Fifty-move rule */
+
+		/* Turn count */
+
 		fen++;
 	}
 }
diff --git a/src/pos.h b/src/pos.h
@@ -22,4 +22,4 @@ struct pos {
 	char turn;
 };
 
-void parsefen(pos *, char);
+void parsefen(pos *, char *);