From 25700bcf0f8c4a6cf2aecff90fbde1708444f457 Mon Sep 17 00:00:00 2001
From: cdricms <36056008+cdricms@users.noreply.github.com>
Date: Wed, 20 Dec 2023 21:52:37 +0100
Subject: [PATCH] Convert fen to board array

---
 .gitignore |   2 ++
 main.c     | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 main.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..18adb28
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.dSYM
+main
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..cf305b1
--- /dev/null
+++ b/main.c
@@ -0,0 +1,101 @@
+#include <stdbool.h>
+#include <stdio.h>
+
+typedef unsigned int uint;
+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;
+
+char chrToLower(char chr) {
+  if (chr > 'A' && chr < 'Z')
+    return chr + 32;
+  return chr;
+}
+
+PieceColors piece_getColor(const Piece piece) { return 8 & piece; }
+Piece piece_getColorlessPiece(const Piece piece) {
+  return piece_getColor(piece) ^ piece;
+}
+
+// Starter fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
+void fen_parseToArray(const char fen[75], Square board[64]) {
+  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;
+      }
+    }
+  }
+}
+
+int main() {
+  Square board[64];
+  char fen[75] = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";
+  fen_parseToArray(fen, board);
+  for (int i = 0; i < 64; i++) {
+    if (i % 8 == 0) {
+      printf("\n");
+    }
+    printf("%d\t", board[i].piece);
+  }
+  return 0;
+}