GitHub issue #47: add test and fix

src/ECS/Query/Chunk.cs

@@ -68,23 +68,23 @@ public readonly struct Chunk<T>
     /// </code>
     /// </remarks>
     public              Span<TTo>  AsSpan256<TTo>() where TTo : struct
-                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, 0, (Length + StructPadding<T>.PadCount256) & 0x7fff_ffe0));
+                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, start, (Length + StructPadding<T>.PadCount256) & 0x7fff_ffe0));
 
     /// <summary>
     /// Return the components as a <see cref="Span{TTo}"/> of type <typeparamref name="TTo"/>.<br/>
     /// The returned <see cref="Span{TTo}"/> contains padding elements on its tail to enable assignment to Vector128{TTo}.<br/>
     /// See <a href="https://friflo.gitbook.io/friflo.engine.ecs/documentation/query-optimization#query-vectorization-simd">Example.</a>.
     /// </summary>
     public              Span<TTo>  AsSpan128<TTo>() where TTo : struct
-                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, 0, (Length + StructPadding<T>.PadCount128) & 0x7fff_fff0));
+                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, start, (Length + StructPadding<T>.PadCount128) & 0x7fff_fff0));
 
     /// <summary>
     /// Return the components as a <see cref="Span{TTo}"/> of type <typeparamref name="TTo"/>.<br/>
     /// The returned <see cref="Span{TTo}"/> contains padding elements on its tail to enable assignment to Vector512.<br/>
     ///  See <a href="https://friflo.gitbook.io/friflo.engine.ecs/documentation/query-optimization#query-vectorization-simd">Example.</a>.
     /// </summary>
     public              Span<TTo>  AsSpan512<TTo>() where TTo : struct
-                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, 0, (Length + StructPadding<T>.PadCount512) & 0x7fff_ffc0));
+                        => MemoryMarshal.Cast<T, TTo>(new Span<T>(ArchetypeComponents, start, (Length + StructPadding<T>.PadCount512) & 0x7fff_ffc0));
 
     /// <summary>
     /// The step value in a for loop when converting a <see cref="AsSpan128{TTo}"/> value to a Vector128{T}.

src/Tests/ECS/Github/Test_GitHub_47.cs

@@ -0,0 +1,35 @@
+using System;
+using Friflo.Engine.ECS;
+using NUnit.Framework;
+using Tests.Utils;
+
+// ReSharper disable InconsistentNaming
+namespace Tests.ECS.Github
+{
+    /// https://github.com/friflo/Friflo.Engine.ECS/issues/47
+    public static class Test_GitHub_47
+    {
+        [Test]
+        public static void Parallel_QueryJob_using_AsSpan()
+        {
+            const int threads = 2;
+            Console.WriteLine("Threads count: "+ threads);
+            var runner  = new ParallelJobRunner(threads);
+            var store = new EntityStore() {JobRunner = runner};
+            for (int n = 0; n < 64; n++) {
+                store.CreateEntity(new MyComponent1 { a = n });
+            }
+
+            var query = store.Query<MyComponent1>();
+            var queryJob = query.ForEach((chunk, _) =>
+            {
+                Span<int> values = chunk.AsSpan256<int>();
+                for (int i = 0; i < values.Length; i++) {
+                    Mem.AreEqual(chunk[i].a, values[i]);
+                }
+            });
+            queryJob.MinParallelChunkLength = 16;
+            queryJob.RunParallel();
+        }
+    }
+}