From 2c0f29a89263b7a0404334ee6b5a93bf5995d808 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 5 Jul 2026 11:25:22 +0100
Subject: Support Int64 in java-transient-0

---
 .../java/org/zwobble/example/Transient0Tests.java  | 15 +++++++
 examples/10-transient-0/src/data.hob               |  5 +++
 .../javatransient0/JavaTransient0Generator.java    | 52 +++++++++++++++-------
 3 files changed, 57 insertions(+), 15 deletions(-)

diff --git a/examples/10-transient-0/output/java-junit/src/test/java/org/zwobble/example/Transient0Tests.java b/examples/10-transient-0/output/java-junit/src/test/java/org/zwobble/example/Transient0Tests.java
index 232ecf1..09a23a3 100644
--- a/examples/10-transient-0/output/java-junit/src/test/java/org/zwobble/example/Transient0Tests.java
+++ b/examples/10-transient-0/output/java-junit/src/test/java/org/zwobble/example/Transient0Tests.java
@@ -7,6 +7,7 @@ import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.zwobble.example.types.data.HobgoblinTransient0Data;
 import org.zwobble.example.types.data.StructWithInt32;
+import org.zwobble.example.types.data.StructWithInt64;
 
 public class Transient0Tests {
     @Test
@@ -22,4 +23,18 @@ public class Transient0Tests {
 
         Assertions.assertEquals(value, decodedValue);
     }
+
+    @Test
+    public void structWithInt64() throws IOException {
+        var value = new StructWithInt64(10, 25);
+
+        var outputStream = new ByteArrayOutputStream();
+        HobgoblinTransient0Data.encodeStructWithInt64(value, outputStream);
+        var bytes = outputStream.toByteArray();
+
+        var inputStream = new ByteArrayInputStream(bytes);
+        var decodedValue = HobgoblinTransient0Data.decodeStructWithInt64(inputStream);
+
+        Assertions.assertEquals(value, decodedValue);
+    }
 }
diff --git a/examples/10-transient-0/src/data.hob b/examples/10-transient-0/src/data.hob
index 4cc43ad..e447f21 100644
--- a/examples/10-transient-0/src/data.hob
+++ b/examples/10-transient-0/src/data.hob
@@ -2,3 +2,8 @@ struct StructWithInt32 {
     field a: Int32;
     field b: Int32;
 }
+
+struct StructWithInt64 {
+    field a: Int64;
+    field b: Int64;
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
index b18c30a..9d8a428 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatransient0/JavaTransient0Generator.java
@@ -191,6 +191,8 @@ public class JavaTransient0Generator implements Generator {
             case SimpleNativeType simpleNativeType ->  {
                 if (simpleNativeType.equals(NativeTypes.INT_32)) {
                     yield generateEncodeInt32(value);
+                } else if (simpleNativeType.equals(NativeTypes.INT_64)) {
+                    yield generateEncodeInt64(value);
                 } else {
                     throw new UnsupportedOperationException("TODO");
                 }
@@ -227,6 +229,8 @@ public class JavaTransient0Generator implements Generator {
             case SimpleNativeType simpleNativeType ->  {
                 if (simpleNativeType.equals(NativeTypes.INT_32)) {
                     yield generateDecodeInt32(target);
+                } else if (simpleNativeType.equals(NativeTypes.INT_64)) {
+                    yield generateDecodeInt64(target);
                 } else {
                     throw new UnsupportedOperationException("TODO");
                 }
@@ -260,26 +264,44 @@ public class JavaTransient0Generator implements Generator {
         return generateDecodeInt(target, 32, JavaTypeRef.INT);
     }
 
+    private static Stream<JavaBlockStatement> generateEncodeInt64(JavaExpression value) {
+        return generateEncodeInt(value, 64);
+    }
+
+    private static Stream<JavaBlockStatement> generateDecodeInt64(
+        JavaIdentifier target
+    ) {
+        return generateDecodeInt(target, 64, JavaTypeRef.INT);
+    }
+
     private static Stream<JavaBlockStatement> generateEncodeInt(
         JavaExpression value,
         int bits
     ) {
         return byteIndicesInBits(bits)
-            .mapToObj(shiftBy -> new JavaExpressionStatement(
-                new JavaMethodCall(
-                    new JavaRef(OUTPUT_STREAM_NAME),
-                    JavaIdentifier.of("write"),
-                    List.of(new JavaBinaryOperation(
-                        JavaBinaryOperator.BITWISE_AND,
-                        new JavaBinaryOperation(
-                            JavaBinaryOperator.UNSIGNED_RIGHT_SHIFT,
-                            value,
-                            new JavaIntegerLiteral(shiftBy)
-                        ),
-                        new JavaIntegerLiteral(0xff)
-                    ))
-                )
-            ));
+            .mapToObj(shiftBy -> {
+                JavaExpression byteToWrite = new JavaBinaryOperation(
+                    JavaBinaryOperator.BITWISE_AND,
+                    new JavaBinaryOperation(
+                        JavaBinaryOperator.UNSIGNED_RIGHT_SHIFT,
+                        value,
+                        new JavaIntegerLiteral(shiftBy)
+                    ),
+                    new JavaIntegerLiteral(0xff)
+                );
+
+                if (bits > 32) {
+                    byteToWrite = new JavaCast(JavaTypeRef.INT, byteToWrite);
+                }
+
+                return new JavaExpressionStatement(
+                    new JavaMethodCall(
+                        new JavaRef(OUTPUT_STREAM_NAME),
+                        JavaIdentifier.of("write"),
+                        List.of(byteToWrite)
+                    )
+                );
+            });
     }
 
     private static Stream<JavaBlockStatement> generateDecodeInt(
-- 
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