UserspaceEmulator: Start sketching out a SoftMMU class :^)

This Emulator sub-object will keep track of all active memory regions
and handle memory read/write operations from the CPU.

A memory region is currently represented by a virtual Region object
that can implement arbitrary behavior by overriding read/write ops.

1 files changed, 67 insertions, 0 deletions

diff --git a/DevTools/UserspaceEmulator/SoftMMU.cpp b/DevTools/UserspaceEmulator/SoftMMU.cpp
new file mode 100644
index 0000000000..0545894ac8
--- /dev/null
+++ b/DevTools/UserspaceEmulator/SoftMMU.cpp
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "SoftMMU.h"
+
+namespace UserspaceEmulator {
+
+SoftMMU::Region* SoftMMU::find_region(u32 address)
+{
+    for (auto& region : m_regions) {
+        if (region.contains(address))
+            return &region;
+    }
+    return nullptr;
+}
+
+void SoftMMU::add_region(NonnullOwnPtr<Region> region)
+{
+    ASSERT(!find_region(region->base()));
+    // FIXME: More sanity checks pls
+    m_regions.append(move(region));
+}
+
+u32 SoftMMU::read32(u32 address)
+{
+    auto* region = find_region(address);
+    if (!region) {
+        TODO();
+    }
+
+    return region->read32(address - region->base());
+}
+
+void SoftMMU::write32(u32 address, u32 value)
+{
+    auto* region = find_region(address);
+    if (!region) {
+        TODO();
+    }
+
+    region->write32(address - region->base(), value);
+}
+
+}