Modules and Makefile

src/board.c

@@ -0,0 +1,6 @@
+#include "board.h"
+
+PieceColors piece_getColor(const Piece piece) { return Black & piece; }
+Piece piece_getColorlessPiece(const Piece piece) {
+  return piece_getColor(piece) ^ piece;
+}

src/board.h

@@ -0,0 +1,18 @@
+#ifndef __BOARD_HEADER
+#include "common.h"
+typedef int Piece;
+typedef enum { Pawn = 0, Knight, Bishop, Rook, Queen, King } Pieces;
+typedef enum { White = 0, Black = 8 } PieceColors;
+
+typedef struct {
+  Piece piece;
+  uint row;
+  uint column;
+} Square;
+
+typedef Square Board[64];
+
+PieceColors piece_getColor(const Piece piece);
+Piece piece_getColorlessPiece(const Piece piece);
+
+#endif // !__BOARD_HEADER

src/common.c

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+#include "common.h"
+
+char chrToLower(char chr) {
+  if (chr >= 'A' && chr <= 'Z')
+    return chr + 32;
+  return chr;
+}
+
+char chrToUpper(char chr) {
+  if (chr >= 'a' && chr <= 'z')
+    return chr - 32;
+  return chr;
+}

src/common.h

@@ -0,0 +1,9 @@
+#ifndef __COMMON_HEADER
+#include <stdbool.h>
+#include <stdio.h>
+typedef unsigned int uint;
+
+char chrToLower(char chr);
+char chrToUpper(char chr);
+
+#endif // !__COMMON_HEADER

src/fen.c

@@ -0,0 +1,118 @@
+#include "fen.h"
+// Starter fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
+void fen_toBoard(const FEN fen, Board board) {
+  uint i = 0;
+  char fen_char;
+  uint row = 8;
+  uint column = 0;
+  uint board_i;
+  while ((fen_char = fen[i++]) != 0) {
+    if (fen_char == '/') {
+      row--;
+      column = 0;
+      continue;
+    }
+    // Upper case or lower case
+    bool is_upper_case;
+    if ((is_upper_case = fen_char > 'A' && fen_char < 'Z') ||
+        (fen_char > 'a' && fen_char < 'z')) {
+      char lowered_char = chrToLower(fen_char);
+      Pieces p;
+      switch (lowered_char) {
+      case 'p':
+        p = Pawn;
+        break;
+      case 'n':
+        p = Knight;
+        break;
+      case 'b':
+        p = Bishop;
+        break;
+      case 'r':
+        p = Rook;
+        break;
+      case 'q':
+        p = Queen;
+        break;
+      case 'k':
+        p = King;
+        break;
+      default:
+        printf("[ERROR] %c is not an authorized character\n", fen_char);
+        return;
+      }
+      PieceColors color = is_upper_case ? White : Black;
+      Piece piece = p ^ color;
+      Square square = {.piece = piece, .row = row, .column = ++column};
+      board[board_i++] = square;
+    } else if (fen_char > '0' && fen_char < '9') {
+      // if the char is a number bet. 1 and 8
+      // we increment the i by its real value (1..=8)
+      int offset = fen_char - '0';
+      if (offset < 9) {
+        for (int j = 0; j < offset; j++) {
+          Square square = {.piece = -1, .row = row, .column = ++column};
+          board[board_i++] = square;
+        }
+      } else {
+        printf("[ERROR]: On character %d of FEN, %c is out of range.", i,
+               fen_char);
+        return;
+      }
+    }
+  }
+}
+
+void fen_fromBoard(const Board board, FEN fen) {
+  // Reset fen
+  uint fen_i = 0;
+  while (fen[fen_i] != 0)
+    fen[fen_i++] = 0;
+
+  fen_i = 0;
+  uint board_i = 0;
+  while (board_i < 64) {
+
+    if (board_i != 0 && board_i % 8 == 0)
+      fen[fen_i++] = '/';
+
+    Square square = board[board_i++];
+    if (square.piece == -1) {
+      uint num = 1;
+      while (board_i % 8 != 0 && (square = board[board_i]).piece == -1) {
+        board_i++;
+        num++;
+      }
+      fen[fen_i++] = num + '0';
+      continue;
+    }
+
+    char fen_char;
+    switch (piece_getColorlessPiece(square.piece)) {
+    case Pawn:
+      fen_char = 'p';
+      break;
+    case Knight:
+      fen_char = 'n';
+      break;
+    case Bishop:
+      fen_char = 'b';
+      break;
+    case Rook:
+      fen_char = 'r';
+      break;
+    case Queen:
+      fen_char = 'q';
+      break;
+    case King:
+      fen_char = 'k';
+      break;
+    default:
+      printf("[ERROR]");
+      return;
+    }
+    if (piece_getColor(square.piece) == White)
+      fen_char = chrToUpper(fen_char);
+    fen[fen_i++] = fen_char;
+  }
+}

src/fen.h

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+#ifndef __FEN_HEADER
+#include "board.h"
+#include "common.h"
+
+typedef char FEN[75];
+void fen_fromBoard(const Board board, FEN fen);
+void fen_toBoard(const FEN fen, Board board);
+
+#endif // !__FEN_HEADER

src/main.c

@@ -0,0 +1,10 @@
+#include "fen.h"
+
+int main() {
+  Board board;
+  FEN fen = "rnbqkbnr/ppppp1pp/5p2/8/8/8/PPPPPPPP/RNBQKBNR";
+  fen_toBoard(fen, board);
+  fen_fromBoard(board, fen);
+  printf("%s", fen);
+  return 0;
+}