From f8f1a67a61bf9db057b55466dcad1d049d542cc6 Mon Sep 17 00:00:00 2001
From: mike <michael@appmodel.nl>
Date: Mon, 12 Jan 2026 07:07:49 +0100
Subject: [PATCH] introduce bitloops

---
 src/main/java/puzzle/SwedishGenerator.java    | 38 ++-----------------
 .../java/puzzle/SwedishGeneratorTest.java     | 31 +++++++++++++++
 2 files changed, 34 insertions(+), 35 deletions(-)

diff --git a/src/main/java/puzzle/SwedishGenerator.java b/src/main/java/puzzle/SwedishGenerator.java
index cfb9927..18a4325 100644
--- a/src/main/java/puzzle/SwedishGenerator.java
+++ b/src/main/java/puzzle/SwedishGenerator.java
@@ -175,7 +175,7 @@ public record SwedishGenerator(Rng rng) {
          this.hi = hi;
       }
       static Grid createEmpty()        { return new Grid(new byte[SIZE], X, X); }
-      int digitAt(int index)           { return g[index] - 48; }
+      int digitAt(int index)           { return g[index] & ~48; }
       public static int r(int offset)  { return offset & 7; }
       public static int c(int offset)  { return offset >>> 3; }
       static int offset(int r, int c)  { return r | (c << 3); }
@@ -344,38 +344,7 @@ public record SwedishGenerator(Rng rng) {
       }
    }
    
-   static int intersectSorted(int[] a, int aLen, int[] b, int bLen, int[] out) {
-      if (aLen == 0 || bLen == 0) return 0;
-      if (aLen < bLen >>> 4) {
-         int k = 0;
-         for (int i = 0; i < aLen; i++) {
-            int x = a[i];
-            if (Arrays.binarySearch(b, 0, bLen, x) >= 0) out[k++] = x;
-         }
-         return k;
-      }
-      if (bLen < aLen >>> 4) {
-         int k = 0;
-         for (int i = 0; i < bLen; i++) {
-            int y = b[i];
-            if (Arrays.binarySearch(a, 0, aLen, y) >= 0) out[k++] = y;
-         }
-         return k;
-      }
-      int i = 0, j = 0, k = 0, x, y;
-      while (i < aLen && j < bLen) {
-         x = a[i];
-         y = b[j];
-         if (x == y) {
-            out[k++] = x;
-            i++;
-            j++;
-         } else if (x < y) i++;
-         else j++;
-      }
-      return k;
-   }
-   
+
    static record Slot(int key, long packedPos) {
       
       static final int BIT_FOR_DIR = 3;
@@ -428,7 +397,7 @@ public record SwedishGenerator(Rng rng) {
       
       for (int i = 0; i < 65; i += 64) {
          for (long bits = (i == 0 ? lo_cl : hi_cl); bits != X; bits &= bits - 1) {
-            int  clueIdx = i + Long.numberOfTrailingZeros(bits);
+            int  clueIdx = i | Long.numberOfTrailingZeros(bits);
             var  d       = grid.digitAt(clueIdx);
             var  nbrs16  = OFFSETS[d];
             long packed  = nbrs16.path()[clueIdx];
@@ -778,7 +747,6 @@ public record SwedishGenerator(Rng rng) {
       val multiThreaded = Thread.currentThread().getName().contains("pool");
       val grid          = mask.deepCopyGrid();
       val used          = new Bit1029();
-      //   val     assigned      = new HashMap<Integer, Lemma>();
       
       long[] assigned = new long[BIGG];
       val    ctx      = CTX.get();
diff --git a/src/test/java/puzzle/SwedishGeneratorTest.java b/src/test/java/puzzle/SwedishGeneratorTest.java
index 134d9f5..e6b6a26 100644
--- a/src/test/java/puzzle/SwedishGeneratorTest.java
+++ b/src/test/java/puzzle/SwedishGeneratorTest.java
@@ -161,6 +161,37 @@ public class SwedishGeneratorTest {
       assertTrue(Slot.horiz(2)); // right
       assertFalse(Slot.horiz(3)); // down
    }
+   static int intersectSorted(int[] a, int aLen, int[] b, int bLen, int[] out) {
+      if (aLen == 0 || bLen == 0) return 0;
+      if (aLen < bLen >>> 4) {
+         int k = 0;
+         for (int i = 0; i < aLen; i++) {
+            int x = a[i];
+            if (Arrays.binarySearch(b, 0, bLen, x) >= 0) out[k++] = x;
+         }
+         return k;
+      }
+      if (bLen < aLen >>> 4) {
+         int k = 0;
+         for (int i = 0; i < bLen; i++) {
+            int y = b[i];
+            if (Arrays.binarySearch(a, 0, aLen, y) >= 0) out[k++] = y;
+         }
+         return k;
+      }
+      int i = 0, j = 0, k = 0, x, y;
+      while (i < aLen && j < bLen) {
+         x = a[i];
+         y = b[j];
+         if (x == y) {
+            out[k++] = x;
+            i++;
+            j++;
+         } else if (x < y) i++;
+         else j++;
+      }
+      return k;
+   }
    
    @Test
    void testIntersectSorted() {