1 files changed, 59 insertions, 19 deletions

diff --git a/src/search/pawn_moves.c b/src/search/pawn_moves.c
index f015e7d..5d94571 100644
--- a/src/search/pawn_moves.c
+++ b/src/search/pawn_moves.c
@@ -1,5 +1,4 @@
 #include "../search.h"
-#include <stdio.h>
 #include <assert.h>
 #include <inttypes.h>
 
@@ -15,7 +14,7 @@ bitboard_t get_white_pawn_forwardmoves(moves_t* moves, position_t position) {
   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);
-  bitboard_t first_move_x = x & BITMASK_RANK_C;
+  bitboard_t first_move_x = x & BITMASK_RANK_3;
 
   first_move_x |= (first_move_x << 8) & (~y);
   x |= first_move_x;
@@ -33,8 +32,8 @@ bitboard_t get_black_pawn_forwardmoves(moves_t* moves, position_t position) {
     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);
-  bitboard_t first_move_x = x | BITMASK_RANK_F;
+  bitboard_t x = ~((friendly_pawns >> 8) & y) & (friendly_pawns >> 8);
+  bitboard_t first_move_x = x & BITMASK_RANK_6;
 
   first_move_x |= (first_move_x >> 8) & (~y);
   x |= first_move_x;
@@ -47,38 +46,44 @@ void get_pawn_moves(moves_t* moves, position_t position) {
 
   bitboard_t forward_moves;
   bitboard_t friendly_pawns;
+  bitboard_t enemy_bitboard;
   if (position.turn == WHITE_TURN) {
     forward_moves = get_white_pawn_forwardmoves(moves, position);
     friendly_pawns = position.bitboards[WHITE_PAWN];
+    enemy_bitboard = blacks(position);
   } else {
     forward_moves = get_black_pawn_forwardmoves(moves, position);
     friendly_pawns = position.bitboards[BLACK_PAWN];
+    enemy_bitboard = whites(position);
   }
 
-  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,
+  bitboard_t file_masks[8] = {
+    BITMASK_FILE_A,
+    BITMASK_FILE_B,
+    BITMASK_FILE_C,
+    BITMASK_FILE_D,
+    BITMASK_FILE_E,
+    BITMASK_FILE_F,
+    BITMASK_FILE_G,
+    BITMASK_FILE_H,
   };
 
   for (int i = 0; i < 8; i++) {
-    bitboard_t item = column_masks[i] & forward_moves;
-    bitboard_t pawns = column_masks[i] & friendly_pawns;
+    bitboard_t item = file_masks[i] & forward_moves;
+    bitboard_t pawns = file_masks[i] & friendly_pawns;
 
     int from = __builtin_ctzll(pawns);
     pawns &= (pawns - 1);
     int next_from = __builtin_ctzll(pawns);
+    if (pawns == 0) next_from = 64; // to work around UB
+    
     while (item) {
       int to = __builtin_ctzll(item);
       if (to > next_from) {
         from = next_from;
         pawns &= (pawns - 1);
         next_from = __builtin_ctzll(pawns);
+        if (pawns == 0) next_from = 64;
       }
       item &= (item - 1);
       add_move(moves, from, to);
@@ -90,11 +95,11 @@ void get_pawn_moves(moves_t* moves, position_t position) {
     int rank_shift;
     int from_shift;
     if (position.turn == WHITE_TURN) {
-      PASSANT_RANK = BITMASK_RANK_E;
+      PASSANT_RANK = BITMASK_RANK_5;
       rank_shift = 40;
       from_shift = -9;
     } else {
-      PASSANT_RANK = BITMASK_RANK_D;
+      PASSANT_RANK = BITMASK_RANK_4;
       from_shift = 7;
       rank_shift = 16;
     }
@@ -103,7 +108,7 @@ void get_pawn_moves(moves_t* moves, position_t position) {
     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;
+      bitboard_t MASK = file_masks[left - 1] & friendly_pawns & PASSANT_RANK;
       if (MASK != 0) {
         add_move(
           moves,
@@ -113,7 +118,7 @@ void get_pawn_moves(moves_t* moves, position_t position) {
       }
     }
     if (right != 0) {
-      bitboard_t MASK = column_masks[right - 1] & friendly_pawns & PASSANT_RANK;
+      bitboard_t MASK = file_masks[right - 1] & friendly_pawns & PASSANT_RANK;
       if (MASK != 0) {
         add_move(
           moves,
@@ -123,4 +128,39 @@ void get_pawn_moves(moves_t* moves, position_t position) {
       }
     }
   }
+
+
+  bitboard_t ATTACK_MASK;
+  int shift;
+  if (position.turn == WHITE_TURN) {
+    shift = 0;
+  } else {
+    shift = -16;
+  }
+  for (int i = 0; i < 8; i++) {
+    if (i == 0) ATTACK_MASK = 512;
+    else if (i == 7) ATTACK_MASK = 128;
+    else {
+      ATTACK_MASK = 640;
+    }
+    bitboard_t pawns = file_masks[i] & friendly_pawns;
+    while (pawns) {
+      int from = __builtin_ctzll(pawns);
+      pawns &= pawns - 1;
+
+      bitboard_t MASK; 
+      if (from + shift > 0) {
+        MASK = ATTACK_MASK << (from + shift);
+      } else {
+        MASK = ATTACK_MASK >> -(from + shift);
+      }
+
+      MASK &= enemy_bitboard;
+      while (MASK) {
+        int to = __builtin_ctzll(MASK);
+        MASK &= MASK - 1;
+        add_move(moves, from, to);
+      }
+    }
+  }
 }