From 2dfa7cecdacacf7ef84e1ca768db6d636e225a0c Mon Sep 17 00:00:00 2001
From: eug-vs <eugene@eug-vs.xyz>
Date: Wed, 14 Sep 2022 05:43:13 +0300
Subject: feat: compute pawn attack table

---
 src/main.c | 43 ++++++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 15 deletions(-)

(limited to 'src/main.c')

diff --git a/src/main.c b/src/main.c
index c8c82cf..d6aa2b8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,12 +2,11 @@
 #include "board.h"
 
 int main() {
-  {
-    start_test_section("Bitboards");
+  start_test_section("Bitboards"); {
     unit_test(pop_count(0b01110) == 3, "Pop count of 01110 is 3");
   }
-  {
-    start_test_section("Default FEN string");
+
+  start_test_section("Default FEN string"); {
     Board board = parse_FEN("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
     unit_test(pop_count(board.pieces[PAWN] | board.pieces[PAWN | BLACK]) == 16, "There are 16 pawns total");
     unit_test(pop_count(board.pieces[ROOK]) == 2, "There are 2 white rooks");
@@ -16,8 +15,8 @@ int main() {
     unit_test(board.castling_rights == 0, "Both sides can castle");
     unit_test(board.en_passant_square == 0, "No en passant move is avaialble");
   }
-  {
-    start_test_section("Test knight attacks");
+
+  start_test_section("Test knight attacks"); {
     Bitboard attacks[64];
     precompute_knight_attack_table(attacks);
 
@@ -33,8 +32,8 @@ int main() {
         "Knight on b7 attacks only d8, d6, c5, a5"
     );
   }
-  {
-    start_test_section("Test king attacks");
+
+  start_test_section("Test king attacks"); {
     Bitboard attacks[64];
     precompute_king_attack_table(attacks);
 
@@ -45,16 +44,30 @@ int main() {
     }
     unit_test(max_attacks == 8, "Max amount of king attacks should be 8");
 
-    {
-      U64 bit = 1;
-      unit_test(
-          attacks[h2] == ((BIT << h1) | (BIT << g1) | (BIT << g2) | (BIT << g3) | (BIT << h3)),
-          "King on h2 attacks only h1, g1, g2, g3, h3"
-      );
-    }
+    unit_test(
+        attacks[h2] == ((BIT << h1) | (BIT << g1) | (BIT << g2) | (BIT << g3) | (BIT << h3)),
+        "King on h2 attacks only h1, g1, g2, g3, h3"
+    );
   }
 
+  start_test_section("Test pawn attacks"); {
+    Bitboard white_attacks[64];
+    Bitboard black_attacks[64];
 
+    precompute_pawn_attack_table(white_attacks, WHITE);
+    precompute_pawn_attack_table(black_attacks, BLACK);
+
+    int is_same = 0;
+    int max_attacks = 0;
+    for (int i = 0; i < 64; i++) {
+      int attack_count = pop_count(white_attacks[i]);
+      if (attack_count > max_attacks) max_attacks = attack_count;
+      if (white_attacks[i] == black_attacks[i]) is_same = 1;
+    }
+    unit_test(max_attacks == 2, "Max amount of pawn attacks should be 2");
+    unit_test(is_same == 0, "Black and white pawns always move differently");
+    unit_test(white_attacks[g2] == (BIT << h3 | BIT << f3), "White pawn on g2 attacks only h3 and f3");
+  }
 
   report();
   return 0;
-- 
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