From 9ff787bf61a4124d93107f3ae45881b26f3329a1 Mon Sep 17 00:00:00 2001
From: Subv <subv2112@gmail.com>
Date: Wed, 10 Oct 2018 18:59:27 -0500
Subject: [PATCH] Kernel/Memory: Added a function to first a suitable guest
 address at which to allocate a region of a given size.

---
 src/core/hle/kernel/vm_manager.cpp | 22 ++++++++++++++++++++++
 src/core/hle/kernel/vm_manager.h   |  8 ++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/core/hle/kernel/vm_manager.cpp b/src/core/hle/kernel/vm_manager.cpp
index e412309fdd..f79ada52b6 100644
--- a/src/core/hle/kernel/vm_manager.cpp
+++ b/src/core/hle/kernel/vm_manager.cpp
@@ -119,6 +119,28 @@ ResultVal<VMManager::VMAHandle> VMManager::MapMemoryBlock(VAddr target,
     return MakeResult<VMAHandle>(MergeAdjacent(vma_handle));
 }
 
+ResultVal<VAddr> VMManager::FindFreeRegion(u32 size) {
+    VAddr base = GetAddressSpaceBaseAddress();
+
+    // Find the first Free VMA.
+    VMAHandle vma_handle = std::find_if(vma_map.begin(), vma_map.end(), [&](const auto& vma) {
+        if (vma.second.type != VMAType::Free)
+            return false;
+
+        VAddr vma_end = vma.second.base + vma.second.size;
+        return vma_end > base && vma_end >= base + size;
+    });
+
+    if (vma_handle == vma_map.end()) {
+        // TODO(Subv): Find the correct error code here.
+        return ResultCode(-1);
+    }
+
+    VAddr target = std::max(base, vma_handle->second.base);
+
+    return MakeResult<VAddr>(target);
+}
+
 ResultVal<VMManager::VMAHandle> VMManager::MapBackingMemory(VAddr target, u8* memory, u64 size,
                                                             MemoryState state) {
     ASSERT(memory != nullptr);
diff --git a/src/core/hle/kernel/vm_manager.h b/src/core/hle/kernel/vm_manager.h
index 015559a64c..096205134d 100644
--- a/src/core/hle/kernel/vm_manager.h
+++ b/src/core/hle/kernel/vm_manager.h
@@ -147,6 +147,14 @@ public:
     ResultVal<VMAHandle> MapMemoryBlock(VAddr target, std::shared_ptr<std::vector<u8>> block,
                                         std::size_t offset, u64 size, MemoryState state);
 
+    /**
+     * Finds the first free address that can hold a region of the desired size.
+     *
+     * @param size Size of the desired region.
+     * @returns The found free address.
+     */
+    ResultVal<VAddr> FindFreeRegion(u32 size);
+
     /**
      * Maps an unmanaged host memory pointer at a given address.
      *