RandomNumberEngine: add the seed() method

stephengold · Feb 7, 2025 · a67f879 · a67f879
1 parent 069e9d0
commit a67f879
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Showing 5 changed files with 58 additions and 1 deletion.
diff --git a/src/main/java/com/github/stephengold/joltjni/std/DefaultRandomEngine.java b/src/main/java/com/github/stephengold/joltjni/std/DefaultRandomEngine.java
@@ -70,6 +70,17 @@ public int nextInt() {
 
         return result;
     }
+
+    /**
+     * Seed the engine with the specified value.
+     *
+     * @param value the value to use
+     */
+    @Override
+    public void seed(int value) {
+        long generatorVa = va();
+        setSeed(generatorVa, value);
+    }
     // *************************************************************************
     // native private methods
 
@@ -80,4 +91,6 @@ public int nextInt() {
     native private static void free(long generatorVa);
 
     native private static int nextInt(long generatorVa);
+
+    native private static void setSeed(long generatorVa, int value);
 }
diff --git a/src/main/java/com/github/stephengold/joltjni/std/Mt19937.java b/src/main/java/com/github/stephengold/joltjni/std/Mt19937.java
@@ -68,6 +68,17 @@ public int nextInt() {
 
         return result;
     }
+
+    /**
+     * Seed the engine with the specified value.
+     *
+     * @param value the value to use
+     */
+    @Override
+    public void seed(int value) {
+        long generatorVa = va();
+        setSeed(generatorVa, value);
+    }
     // *************************************************************************
     // native private methods
 
@@ -78,4 +89,6 @@ public int nextInt() {
     native private static void free(long generatorVa);
 
     native private static int nextInt(long generatorVa);
+
+    native private static void setSeed(long generatorVa, int value);
 }
diff --git a/src/main/java/com/github/stephengold/joltjni/std/RandomNumberEngine.java b/src/main/java/com/github/stephengold/joltjni/std/RandomNumberEngine.java
@@ -38,4 +38,11 @@ public interface RandomNumberEngine extends ConstJoltPhysicsObject {
      * @return an integer value
      */
     int nextInt();
+
+    /**
+     * Seed the engine with the specified value.
+     *
+     * @param value the value to set
+     */
+    void seed(int value);
 }
diff --git a/src/main/native/glue/d/DefaultRandomEngine.cpp b/src/main/native/glue/d/DefaultRandomEngine.cpp
@@ -1,5 +1,5 @@
 /*
-Copyright (c) 2024 Stephen Gold
+Copyright (c) 2024-2025 Stephen Gold
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -77,4 +77,16 @@ JNIEXPORT jint JNICALL Java_com_github_stephengold_joltjni_std_DefaultRandomEngi
             = reinterpret_cast<default_random_engine *> (generatorVa);
     default_random_engine::result_type result = (*pGenerator)();
     return result;
+}
+
+/*
+ * Class:     com_github_stephengold_joltjni_std_DefaultRandomEngine
+ * Method:    setSeed
+ * Signature: (JI)V
+ */
+JNIEXPORT void JNICALL Java_com_github_stephengold_joltjni_std_DefaultRandomEngine_setSeed
+  (JNIEnv *, jclass, jlong generatorVa, jint value) {
+    default_random_engine * const pGenerator
+            = reinterpret_cast<default_random_engine *> (generatorVa);
+    pGenerator->seed(value);
 }
diff --git a/src/main/native/glue/m/Mt19937.cpp b/src/main/native/glue/m/Mt19937.cpp
@@ -76,4 +76,16 @@ JNIEXPORT jint JNICALL Java_com_github_stephengold_joltjni_std_Mt19937_nextInt
             = reinterpret_cast<mt19937 *> (generatorVa);
     mt19937::result_type result = (*pGenerator)();
     return result;
+}
+
+/*
+ * Class:     com_github_stephengold_joltjni_std_Mt19937
+ * Method:    setSeed
+ * Signature: (JI)V
+ */
+JNIEXPORT void JNICALL Java_com_github_stephengold_joltjni_std_Mt19937_setSeed
+  (JNIEnv *, jclass, jlong generatorVa, jint value) {
+    mt19937 * const pGenerator
+            = reinterpret_cast<mt19937 *> (generatorVa);
+    pGenerator->seed(value);
 }