Fix bug in elias fano

Genbox · Genbox · commit 202b9abc62f1 · 2026-02-16T22:15:53.000+01:00
diff --git a/Src/FastData.Generator.CSharp/Internal/Generators/EliasFanoCode.cs b/Src/FastData.Generator.CSharp/Internal/Generators/EliasFanoCode.cs
@@ -56,7 +56,7 @@ public override string Generate()
                  {{(hasLowerBits ?
                      """
                                  ulong targetLow = (ulong)value & _lowerMask;
-                                 long lowerBitsOffset = rank * lowerBitCount;
+                                 long lowerBitsOffset = rank * _lowerBitCount;
 
                                  while (true)
                                  {
@@ -82,7 +82,7 @@ public override string Generate()
                                          int startBit = (int)(lowerBitsOffset & 63);
 
                                          ulong currentLow;
-                                         if (startBit + lowerBitCount <= 64)
+                                         if (startBit + _lowerBitCount <= 64)
                                              currentLow = (_lowerBits[wordIndex] >> startBit) & _lowerMask;
                                          else
                                          {
@@ -104,7 +104,7 @@ public override string Generate()
                                      if ((ulong)rank >= ItemCount)
                                          return false;
 
-                                     lowerBitsOffset += lowerBitCount;
+                                     lowerBitsOffset += _lowerBitCount;
                                  }
                      """
                      : """
diff --git a/Src/FastData.TestHarness.Runner/Verify/Vectors/CSharp/ValueVectors_EliasFanoStructure_Int32_1000_natural_sparse.verified.txt b/Src/FastData.TestHarness.Runner/Verify/Vectors/CSharp/ValueVectors_EliasFanoStructure_Int32_1000_natural_sparse.verified.txt
@@ -59,7 +59,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse
 
         ulong window = _upperBits[currWord] & (ulong.MaxValue << (int)(position & 63));
             ulong targetLow = (ulong)value & _lowerMask;
-            long lowerBitsOffset = rank * lowerBitCount;
+            long lowerBitsOffset = rank * _lowerBitCount;
 
             while (true)
             {
@@ -85,7 +85,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse
                     int startBit = (int)(lowerBitsOffset & 63);
 
                     ulong currentLow;
-                    if (startBit + lowerBitCount <= 64)
+                    if (startBit + _lowerBitCount <= 64)
                         currentLow = (_lowerBits[wordIndex] >> startBit) & _lowerMask;
                     else
                     {
@@ -107,7 +107,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse
                 if ((ulong)rank >= ItemCount)
                     return false;
 
-                lowerBitsOffset += lowerBitCount;
+                lowerBitsOffset += _lowerBitCount;
             }
     }
 

Original file line number	Diff line number	Diff line change
`@@ -59,7 +59,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse`
`59`	`59`
`60`	`60`	`ulong window = _upperBits[currWord] & (ulong.MaxValue << (int)(position & 63));`
`61`	`61`	`ulong targetLow = (ulong)value & _lowerMask;`
`62`		`- long lowerBitsOffset = rank * lowerBitCount;`
	`62`	`+ long lowerBitsOffset = rank * _lowerBitCount;`
`63`	`63`
`64`	`64`	`while (true)`
`65`	`65`	`{`
`@@ -85,7 +85,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse`
`85`	`85`	`int startBit = (int)(lowerBitsOffset & 63);`
`86`	`86`
`87`	`87`	`ulong currentLow;`
`88`		`- if (startBit + lowerBitCount <= 64)`
	`88`	`+ if (startBit + _lowerBitCount <= 64)`
`89`	`89`	`currentLow = (_lowerBits[wordIndex] >> startBit) & _lowerMask;`
`90`	`90`	`else`
`91`	`91`	`{`
`@@ -107,7 +107,7 @@ internal static class EliasFanoStructure_Int32_1000_natural_sparse`
`107`	`107`	`if ((ulong)rank >= ItemCount)`
`108`	`108`	`return false;`
`109`	`109`
`110`		`- lowerBitsOffset += lowerBitCount;`
	`110`	`+ lowerBitsOffset += _lowerBitCount;`
`111`	`111`	`}`
`112`	`112`	`}`
`113`	`113`