memory: Make getter functions const qualified where applicable (#5251)

Many of these functions are capable of being used within const contexts,
so we can apply the const qualifier in some cases and add const based
overloads for others, which makes the interface a little bit more
flexible and const-correct.

src/core/memory.cpp

@@ -266,7 +266,7 @@ void MemorySystem::UnmapRegion(PageTable& page_table, VAddr base, u32 size) {
     MapPages(page_table, base / PAGE_SIZE, size / PAGE_SIZE, nullptr, PageType::Unmapped);
 }
 
-MemoryRef MemorySystem::GetPointerForRasterizerCache(VAddr addr) {
+MemoryRef MemorySystem::GetPointerForRasterizerCache(VAddr addr) const {
     if (addr >= LINEAR_HEAP_VADDR && addr < LINEAR_HEAP_VADDR_END) {
         return {impl->fcram_mem, addr - LINEAR_HEAP_VADDR};
     }
@@ -394,7 +394,7 @@ bool IsValidVirtualAddress(const Kernel::Process& process, const VAddr vaddr) {
     return false;
 }
 
-bool MemorySystem::IsValidPhysicalAddress(const PAddr paddr) {
+bool MemorySystem::IsValidPhysicalAddress(const PAddr paddr) const {
     return GetPhysicalPointer(paddr) != nullptr;
 }
 
@@ -414,6 +414,21 @@ u8* MemorySystem::GetPointer(const VAddr vaddr) {
     return nullptr;
 }
 
+const u8* MemorySystem::GetPointer(const VAddr vaddr) const {
+    const u8* page_pointer = impl->current_page_table->pointers[vaddr >> PAGE_BITS];
+    if (page_pointer) {
+        return page_pointer + (vaddr & PAGE_MASK);
+    }
+
+    if (impl->current_page_table->attributes[vaddr >> PAGE_BITS] ==
+        PageType::RasterizerCachedMemory) {
+        return GetPointerForRasterizerCache(vaddr);
+    }
+
+    LOG_ERROR(HW_Memory, "unknown GetPointer @ 0x{:08x}", vaddr);
+    return nullptr;
+}
+
 std::string MemorySystem::ReadCString(VAddr vaddr, std::size_t max_length) {
     std::string string;
     string.reserve(max_length);
@@ -432,7 +447,11 @@ u8* MemorySystem::GetPhysicalPointer(PAddr address) {
     return GetPhysicalRef(address);
 }
 
-MemoryRef MemorySystem::GetPhysicalRef(PAddr address) {
+const u8* MemorySystem::GetPhysicalPointer(PAddr address) const {
+    return GetPhysicalRef(address);
+}
+
+MemoryRef MemorySystem::GetPhysicalRef(PAddr address) const {
     struct MemoryArea {
         PAddr paddr_base;
         u32 size;
@@ -911,17 +930,22 @@ void WriteMMIO<u64>(MMIORegionPointer mmio_handler, VAddr addr, const u64 data)
     mmio_handler->Write64(addr, data);
 }
 
-u32 MemorySystem::GetFCRAMOffset(const u8* pointer) {
+u32 MemorySystem::GetFCRAMOffset(const u8* pointer) const {
     ASSERT(pointer >= impl->fcram.get() && pointer <= impl->fcram.get() + Memory::FCRAM_N3DS_SIZE);
     return static_cast<u32>(pointer - impl->fcram.get());
 }
 
-u8* MemorySystem::GetFCRAMPointer(u32 offset) {
+u8* MemorySystem::GetFCRAMPointer(std::size_t offset) {
     ASSERT(offset <= Memory::FCRAM_N3DS_SIZE);
     return impl->fcram.get() + offset;
 }
 
-MemoryRef MemorySystem::GetFCRAMRef(u32 offset) {
+const u8* MemorySystem::GetFCRAMPointer(std::size_t offset) const {
+    ASSERT(offset <= Memory::FCRAM_N3DS_SIZE);
+    return impl->fcram.get() + offset;
+}
+
+MemoryRef MemorySystem::GetFCRAMRef(std::size_t offset) const {
     ASSERT(offset <= Memory::FCRAM_N3DS_SIZE);
     return MemoryRef(impl->fcram_mem, offset);
 }

src/core/memory.h

@@ -339,25 +339,30 @@ public:
 
     std::string ReadCString(VAddr vaddr, std::size_t max_length);
 
-    /**
+    /// Gets a pointer to the memory region beginning at the specified physical address.
-     * Gets a pointer to the memory region beginning at the specified physical address.
-     */
     u8* GetPhysicalPointer(PAddr address);
 
-    MemoryRef GetPhysicalRef(PAddr address);
+    /// Gets a pointer to the memory region beginning at the specified physical address.
+    const u8* GetPhysicalPointer(PAddr address) const;
+
+    MemoryRef GetPhysicalRef(PAddr address) const;
 
     u8* GetPointer(VAddr vaddr);
+    const u8* GetPointer(VAddr vaddr) const;
 
-    bool IsValidPhysicalAddress(PAddr paddr);
+    bool IsValidPhysicalAddress(PAddr paddr) const;
 
     /// Gets offset in FCRAM from a pointer inside FCRAM range
-    u32 GetFCRAMOffset(const u8* pointer);
+    u32 GetFCRAMOffset(const u8* pointer) const;
 
     /// Gets pointer in FCRAM with given offset
-    u8* GetFCRAMPointer(u32 offset);
+    u8* GetFCRAMPointer(std::size_t offset);
+
+    /// Gets pointer in FCRAM with given offset
+    const u8* GetFCRAMPointer(std::size_t offset) const;
 
     /// Gets a serializable ref to FCRAM with the given offset
-    MemoryRef GetFCRAMRef(u32 offset);
+    MemoryRef GetFCRAMRef(std::size_t offset) const;
 
     /**
      * Mark each page touching the region as cached.
@@ -385,7 +390,7 @@ private:
      * Since the cache only happens on linear heap or VRAM, we know the exact physical address and
      * pointer of such virtual address
      */
-    MemoryRef GetPointerForRasterizerCache(VAddr addr);
+    MemoryRef GetPointerForRasterizerCache(VAddr addr) const;
 
     void MapPages(PageTable& page_table, u32 base, u32 size, MemoryRef memory, PageType type);