[HLE] Add RandomExports HLE (#413)

src/SharpEmu.Libs/Random/RandomExports.cs

@@ -0,0 +1,39 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using System.Security.Cryptography;
+using SharpEmu.HLE;
+
+namespace SharpEmu.Libs.Random;
+
+public static class RandomExports
+{
+    private const int RandomErrorInvalid = unchecked((int)0x817C0016);
+    private const int MaxRandomBytes = 64;
+
+    [SysAbiExport(
+        Nid = "PI7jIZj4pcE",
+        ExportName = "sceRandomGetRandomNumber",
+        Target = Generation.Gen4 | Generation.Gen5,
+        LibraryName = "libSceRandom")]
+    public static int RandomGetRandomNumber(CpuContext ctx)
+    {
+        var destination = ctx[CpuRegister.Rdi];
+        var size = ctx[CpuRegister.Rsi];
+        if ((destination == 0 && size != 0) || size > MaxRandomBytes)
+        {
+            return ctx.SetReturn(RandomErrorInvalid);
+        }
+
+        if (size == 0)
+        {
+            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK);
+        }
+
+        Span<byte> bytes = stackalloc byte[(int)size];
+        RandomNumberGenerator.Fill(bytes);
+        return ctx.Memory.TryWrite(destination, bytes)
+            ? ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK)
+            : ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
+    }
+}

tests/SharpEmu.Libs.Tests/Random/RandomExportsTests.cs

@@ -0,0 +1,69 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using SharpEmu.HLE;
+using SharpEmu.Libs.Random;
+using Xunit;
+
+namespace SharpEmu.Libs.Tests.Random;
+
+public sealed class RandomExportsTests
+{
+    private const ulong BaseAddress = 0x1000;
+    private const int RandomErrorInvalid = unchecked((int)0x817C0016);
+
+    [Fact]
+    public void GetRandomNumberWritesRequestedBytes()
+    {
+        var memory = new FakeCpuMemory(BaseAddress, 64);
+        var ctx = CreateContext(memory, BaseAddress, 64);
+
+        Assert.Equal(0, RandomExports.RandomGetRandomNumber(ctx));
+
+        var bytes = new byte[64];
+        Assert.True(memory.TryRead(BaseAddress, bytes));
+        Assert.NotEqual(new byte[64], bytes);
+    }
+
+    [Theory]
+    [InlineData(0, 1)]
+    [InlineData(BaseAddress, 65)]
+    public void GetRandomNumberRejectsInvalidArguments(ulong address, ulong size)
+    {
+        var memory = new FakeCpuMemory(BaseAddress, 64);
+        var ctx = CreateContext(memory, address, size);
+
+        Assert.Equal(RandomErrorInvalid, RandomExports.RandomGetRandomNumber(ctx));
+    }
+
+    [Fact]
+    public void GetRandomNumberAcceptsEmptyRequest()
+    {
+        var memory = new FakeCpuMemory(BaseAddress, 64);
+        var ctx = CreateContext(memory, 0, 0);
+
+        Assert.Equal(0, RandomExports.RandomGetRandomNumber(ctx));
+    }
+
+    [Fact]
+    public void GetRandomNumberReportsUnmappedDestination()
+    {
+        var memory = new FakeCpuMemory(BaseAddress, 64);
+        var ctx = CreateContext(memory, BaseAddress + 64, 1);
+
+        Assert.Equal(
+            (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT,
+            RandomExports.RandomGetRandomNumber(ctx));
+    }
+
+    private static CpuContext CreateContext(
+        ICpuMemory memory,
+        ulong destination,
+        ulong size)
+    {
+        var ctx = new CpuContext(memory, Generation.Gen5);
+        ctx[CpuRegister.Rdi] = destination;
+        ctx[CpuRegister.Rsi] = size;
+        return ctx;
+    }
+}