1 files changed, 86 insertions, 7 deletions

diff --git a/src/search/pawn_moves.c b/src/search/pawn_moves.c
index e169c07..f015e7d 100644
--- a/src/search/pawn_moves.c
+++ b/src/search/pawn_moves.c
@@ -1,14 +1,17 @@
 #include "../search.h"
+#include <stdio.h>
 #include <assert.h>
+#include <inttypes.h>
 
-void get_white_pawn_moves(moves_t* moves, position_t position) {
+bitboard_t get_white_pawn_forwardmoves(moves_t* moves, position_t position) {
   bitboard_t enemy_bitboard = blacks(position);
   bitboard_t friendly_pieces =
     position.bitboards[WHITE_KING] |
     position.bitboards[WHITE_QUEEN] |
     position.bitboards[WHITE_ROOK] |
     position.bitboards[WHITE_BISHOP] |
-    position.bitboards[WHITE_KNIGHT];
+    position.bitboards[WHITE_KNIGHT] |
+    position.bitboards[WHITE_PAWN];
   bitboard_t friendly_pawns = position.bitboards[WHITE_PAWN];
   bitboard_t y = friendly_pieces | enemy_bitboard;
   bitboard_t x = ~((friendly_pawns << 8) & y) & (friendly_pawns << 8);
@@ -17,16 +20,17 @@ void get_white_pawn_moves(moves_t* moves, position_t position) {
   first_move_x |= (first_move_x << 8) & (~y);
   x |= first_move_x;
 
-  print_bitboard(x);
+  return x;
 }
-void get_black_pawn_moves(moves_t* moves, position_t position) {
+bitboard_t get_black_pawn_forwardmoves(moves_t* moves, position_t position) {
   bitboard_t enemy_bitboard = whites(position);
   bitboard_t friendly_pieces =
     position.bitboards[BLACK_KING] |
     position.bitboards[BLACK_QUEEN] |
     position.bitboards[BLACK_ROOK] |
     position.bitboards[BLACK_BISHOP] |
-    position.bitboards[BLACK_KNIGHT];
+    position.bitboards[BLACK_KNIGHT] |
+    position.bitboards[BLACK_PAWN];
   bitboard_t friendly_pawns = position.bitboards[BLACK_PAWN];
   bitboard_t y = friendly_pieces | enemy_bitboard;
   bitboard_t x = ~((friendly_pawns << 8) & y) & (friendly_pawns << 8);
@@ -34,14 +38,89 @@ void get_black_pawn_moves(moves_t* moves, position_t position) {
 
   first_move_x |= (first_move_x >> 8) & (~y);
   x |= first_move_x;
+
+  return x;
 }
 
 void get_pawn_moves(moves_t* moves, position_t position) {
   assert_valid_position(position);
 
+  bitboard_t forward_moves;
+  bitboard_t friendly_pawns;
   if (position.turn == WHITE_TURN) {
-    get_white_pawn_moves(moves, position);
+    forward_moves = get_white_pawn_forwardmoves(moves, position);
+    friendly_pawns = position.bitboards[WHITE_PAWN];
   } else {
-    get_black_pawn_moves(moves, position);
+    forward_moves = get_black_pawn_forwardmoves(moves, position);
+    friendly_pawns = position.bitboards[BLACK_PAWN];
+  }
+
+  bitboard_t column_masks[8] = {
+    BITMASK_COLM_1,
+    BITMASK_COLM_2,
+    BITMASK_COLM_3,
+    BITMASK_COLM_4,
+    BITMASK_COLM_5,
+    BITMASK_COLM_6,
+    BITMASK_COLM_7,
+    BITMASK_COLM_8,
+  };
+
+  for (int i = 0; i < 8; i++) {
+    bitboard_t item = column_masks[i] & forward_moves;
+    bitboard_t pawns = column_masks[i] & friendly_pawns;
+
+    int from = __builtin_ctzll(pawns);
+    pawns &= (pawns - 1);
+    int next_from = __builtin_ctzll(pawns);
+    while (item) {
+      int to = __builtin_ctzll(item);
+      if (to > next_from) {
+        from = next_from;
+        pawns &= (pawns - 1);
+        next_from = __builtin_ctzll(pawns);
+      }
+      item &= (item - 1);
+      add_move(moves, from, to);
+    }
+  }
+
+  if (position.passantable_column != 0) {
+    bitboard_t PASSANT_RANK;
+    int rank_shift;
+    int from_shift;
+    if (position.turn == WHITE_TURN) {
+      PASSANT_RANK = BITMASK_RANK_E;
+      rank_shift = 40;
+      from_shift = -9;
+    } else {
+      PASSANT_RANK = BITMASK_RANK_D;
+      from_shift = 7;
+      rank_shift = 16;
+    }
+
+    int left = 0, right = 0;
+    if (position.passantable_column > 1) left = position.passantable_column - 1;
+    if (position.passantable_column < 8) right = position.passantable_column + 1;
+    if (left != 0) {
+      bitboard_t MASK = column_masks[left - 1] & friendly_pawns & PASSANT_RANK;
+      if (MASK != 0) {
+        add_move(
+          moves,
+          left + rank_shift + from_shift,
+          position.passantable_column + rank_shift - 1
+        );
+      }
+    }
+    if (right != 0) {
+      bitboard_t MASK = column_masks[right - 1] & friendly_pawns & PASSANT_RANK;
+      if (MASK != 0) {
+        add_move(
+          moves,
+          right + rank_shift + from_shift,
+          position.passantable_column + rank_shift - 1
+        );
+      }
+    }
   }
 }