From 03a83877a5fa055543ca5bc62adac269cf59dc93 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 24 Jun 2023 19:52:45 +0100
Subject: WASM binary format: support memory sections

---
 .../wasm/structure/ast/modules/WasmMemory.java     |  6 ++++++
 .../wasm/structure/ast/modules/WasmModule.java     | 14 +++++++++++++
 .../structure/binary/WasmBinaryFormatModules.java  | 24 ++++++++++++++++++----
 3 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmMemory.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmMemory.java b/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmMemory.java
new file mode 100644
index 00000000..01f5141a
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmMemory.java
@@ -0,0 +1,6 @@
+package org.shedlang.compiler.backends.wasm.structure.ast.modules;
+
+import org.shedlang.compiler.backends.wasm.structure.ast.types.WasmMemoryType;
+
+public record WasmMemory(WasmMemoryType type) {
+}
diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmModule.java b/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmModule.java
index e37c4641..d8757402 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmModule.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/structure/ast/modules/WasmModule.java
@@ -7,9 +7,11 @@ import org.shedlang.compiler.util.P;
 public record WasmModule(
     PVector<WasmFuncType> types,
     PVector<WasmTable> tables,
+    PVector<WasmMemory> memories,
     PVector<WasmImport> imports
 ) {
     public static final WasmModule EMPTY = new WasmModule(
+        P.vector(),
         P.vector(),
         P.vector(),
         P.vector()
@@ -19,6 +21,7 @@ public record WasmModule(
         return new WasmModule(
             types.plus(type),
             tables,
+            memories,
             imports
         );
     }
@@ -27,6 +30,16 @@ public record WasmModule(
         return new WasmModule(
             types,
             tables.plus(table),
+            memories,
+            imports
+        );
+    }
+
+    public WasmModule addMemory(WasmMemory memory) {
+        return new WasmModule(
+            types,
+            tables,
+            memories.plus(memory),
             imports
         );
     }
@@ -35,6 +48,7 @@ public record WasmModule(
         return new WasmModule(
             types,
             tables,
+            memories,
             imports.plus(import_)
         );
     }
diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/structure/binary/WasmBinaryFormatModules.java b/src/main/java/org/shedlang/compiler/backends/wasm/structure/binary/WasmBinaryFormatModules.java
index bd4525af..8945d7ed 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/structure/binary/WasmBinaryFormatModules.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/structure/binary/WasmBinaryFormatModules.java
@@ -2,10 +2,7 @@ package org.shedlang.compiler.backends.wasm.structure.binary;
 
 import org.pcollections.PVector;
 import org.shedlang.compiler.backends.wasm.structure.BinaryWriter;
-import org.shedlang.compiler.backends.wasm.structure.ast.modules.WasmModule;
-import org.shedlang.compiler.backends.wasm.structure.ast.modules.WasmImport;
-import org.shedlang.compiler.backends.wasm.structure.ast.modules.WasmImportDescriptor;
-import org.shedlang.compiler.backends.wasm.structure.ast.modules.WasmTable;
+import org.shedlang.compiler.backends.wasm.structure.ast.modules.*;
 import org.shedlang.compiler.backends.wasm.structure.ast.types.WasmFuncType;
 
 import java.io.IOException;
@@ -186,6 +183,24 @@ public class WasmBinaryFormatModules {
         writeTableType(table.type(), writer);
     }
 
+    // == Memory Section ==
+
+    private static void writeMemorySection(WasmModule module, BinaryWriter writer) throws IOException {
+        if (module.memories().size() > 0) {
+            writeSection(SectionId.MEMORY, writer, () -> {
+                writeVec(
+                    module.memories(),
+                    memory -> writeMemory(memory, writer),
+                    writer
+                );
+            });
+        }
+    }
+
+    private static void writeMemory(WasmMemory memory, BinaryWriter writer) {
+        writeMemoryType(memory.type(), writer);
+    }
+
     // == Modules ==
 
     private static final byte[] WASM_MAGIC = HexFormat.of().parseHex("0061736D");
@@ -198,6 +213,7 @@ public class WasmBinaryFormatModules {
         writeTypeSection(module.types(), writer);
         writeImportSection(module, writer);
         writeTableSection(module, writer);
+        writeMemorySection(module, writer);
         writeNameSection(module, writer);
 
         outputStream.write(writer.toBytes());
-- 
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