Slightly optimized remaining length calculation by using bit shifting…

… instead.
MeltyPlayer · Nov 25, 2024 · c586fcc · c586fcc
1 parent 5ab6f0f
commit c586fcc
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Showing 2 changed files with 65 additions and 6 deletions.
diff --git a/Schema Tests/binary/attributes/sequence/RSequenceUntilEndOfStreamAttributeTests.cs b/Schema Tests/binary/attributes/sequence/RSequenceUntilEndOfStreamAttributeTests.cs
@@ -102,7 +102,7 @@ public void Write(IBinaryWriter bw) {
   }
 
   [Test]
-  public void TestIntArrayUntilEndOfStream() {
+  public void TestInt24ArrayUntilEndOfStream() {
     BinarySchemaTestUtil.AssertGenerated(
         """
 
@@ -114,6 +114,7 @@ namespace foo.bar;
         [BinarySchema]
         public partial class Wrapper : IBinaryConvertible {
           [RSequenceUntilEndOfStream]
+          [NumberFormat(SchemaNumberType.INT24)]
           public int[] Field { get; set; }
         }
         """,
@@ -126,7 +127,57 @@ namespace foo.bar;
 
         public partial class Wrapper {
           public void Read(IBinaryReader br) {
-            this.Field = br.ReadInt32s((br.Length - br.Position) / 4);
+            this.Field = new int[(br.Length - br.Position) / 3];
+            for (var i = 0; i < this.Field.Length; ++i) {
+              this.Field[i] = br.ReadInt24();
+            }
+          }
+        }
+
+        """,
+        """
+        using System;
+        using schema.binary;
+
+        namespace foo.bar;
+
+        public partial class Wrapper {
+          public void Write(IBinaryWriter bw) {
+            for (var i = 0; i < this.Field.Length; ++i) {
+              bw.WriteInt24(this.Field[i]);
+            }
+          }
+        }
+
+        """);
+  }
+
+  [Test]
+  public void TestInt32ArrayUntilEndOfStream() {
+    BinarySchemaTestUtil.AssertGenerated(
+        """
+
+        using schema.binary;
+        using schema.binary.attributes;
+
+        namespace foo.bar;
+
+        [BinarySchema]
+        public partial class Wrapper : IBinaryConvertible {
+          [RSequenceUntilEndOfStream]
+          public int[] Field { get; set; }
+        }
+        """,
+        """
+        using System;
+        using System.Collections.Generic;
+        using schema.binary;
+
+        namespace foo.bar;
+
+        public partial class Wrapper {
+          public void Read(IBinaryReader br) {
+            this.Field = br.ReadInt32s((br.Length - br.Position) >> 2);
           }
         }
 

diff --git a/Schema/src/binary/text/BinarySchemaReaderGenerator.cs b/Schema/src/binary/text/BinarySchemaReaderGenerator.cs
@@ -579,11 +579,19 @@ var qualifiedElementName
                                             out var size)) {
                 var remainingLengthAccessor =
                     $"{READER}.Length - {READER}.Position";
-                var readCountAccessor = size == 1
-                    ? remainingLengthAccessor
-                    : $"({remainingLengthAccessor}) / {size}";
 
-                // Members that don't need to be cast are the easiest to read.
+                var sizeLog2 = Math.Log(size, 2);
+
+                string readCountAccessor;
+                if (size == 1) {
+                  readCountAccessor = remainingLengthAccessor;
+                } else if (sizeLog2 % 1 == 0) {
+                  readCountAccessor
+                      = $"({remainingLengthAccessor}) >> {sizeLog2}";
+                } else {
+                  readCountAccessor = $"({remainingLengthAccessor}) / {size}";
+                }
+
                 var elementType = arrayType.ElementType;
                 if (SchemaGeneratorUtil.TryToGetLabelForMethodWithoutCast(
                         elementType,