probably BASIC move logic done

src/chess.c

@@ -71,12 +71,65 @@ bool get_move(move_t *move) {
     return is_move_in_bounds(*move);
 }
 
-bool perform_move(player_e player, move_t move) {
-    
+bool compare_pos(pos_t a, pos_t b) {
+    return a.x == b.x && a.y == b.y;
+}
+
+/**
+ * check the wanted pos_t against all valid move options
+ * of the current piece
+ */
+bool is_move_legal(move_t move) {
+    valid_move_t valid_moves[PIECE_COUNT] = DEFAULT_VALID_MOVES;
+    for (int i = 0; i < PIECE_COUNT; i++) {
+        for (int j = 0; 
+            j < valid_moves[i].piece_move_count && 
+            move.piece == valid_moves[i].piece; 
+            j++
+        ) {
+            pos_t new_pos = {move.from.x+move.to.x, move.from.y+move.to.y};
+            if (compare_pos(new_pos, valid_moves[i].options[j]) == true) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+bool is_none(board_t board, pos_t pos) {
+    return board[pos.y][pos.x] == NONE;
+}
+
+// the move can be:
+// 1.  legal x illegal
+// 2.  the 'to' pos could be occupied x non-occupied
+// 2a. it could be capturable x non-capturable
+bool validate_move(board_t board, move_t move) {
+    bool none = is_none(board, move.to);
+    bool move_legal = is_move_legal(move);
+    if (none == true && move_legal == true) {         
+        // free ability to move
+        return true;
+    } else if (none == false && move_legal == true) {
+        // capturing
+        return true;
+    } else {
+        // otherwise, invalid move
+        return false;
+    }
+}
+
+/** TODO: capturing and promotions */
+bool perform_move(board_t *board, player_e player, move_t move) {
+    if (validate_move(*board, move) == true) {
+        *board[move.to.y][move.to.x] = move.piece; // move piece to wanted place
+        *board[move.from.y][move.from.x] = NONE; // erase the remnants
+    }
 }
 
 end_condition_e check_edge_cases(board_t board) {
-
+    
 }
 
 void announce_results(end_condition_e end_condition, player_e player) {