Merge pull request #762 from yuriks/memmap

Memory: Use a table based lookup scheme to read from memory regions

1 files changed, 202 insertions, 0 deletions

diff --git a/src/core/memory.cpp b/src/core/memory.cpp
new file mode 100644
index 000000000..5d8069acd
--- /dev/null
+++ b/src/core/memory.cpp
@@ -0,0 +1,202 @@
+// Copyright 2015 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <array>
+
+#include "common/assert.h"
+#include "common/common_types.h"
+#include "common/logging/log.h"
+#include "common/swap.h"
+
+#include "core/hle/config_mem.h"
+#include "core/hle/shared_page.h"
+#include "core/hw/hw.h"
+#include "core/mem_map.h"
+#include "core/memory.h"
+
+namespace Memory {
+
+const u32 PAGE_MASK = PAGE_SIZE - 1;
+const int PAGE_BITS = 12;
+
+enum class PageType {
+    /// Page is unmapped and should cause an access error.
+    Unmapped,
+    /// Page is mapped to regular memory. This is the only type you can get pointers to.
+    Memory,
+    /// Page is mapped to a I/O region. Writing and reading to this page is handled by functions.
+    Special,
+};
+
+/**
+ * A (reasonably) fast way of allowing switchable and remmapable process address spaces. It loosely
+ * mimics the way a real CPU page table works, but instead is optimized for minimal decoding and
+ * fetching requirements when acessing. In the usual case of an access to regular memory, it only
+ * requires an indexed fetch and a check for NULL.
+ */
+struct PageTable {
+    static const size_t NUM_ENTRIES = 1 << (32 - PAGE_BITS);
+
+    /**
+     * Array of memory pointers backing each page. An entry can only be non-null if the
+     * corresponding entry in the `attributes` array is of type `Memory`.
+     */
+    std::array<u8*, NUM_ENTRIES> pointers;
+
+    /**
+     * Array of fine grained page attributes. If it is set to any value other than `Memory`, then
+     * the corresponding entry in `pointer` MUST be set to null.
+     */
+    std::array<PageType, NUM_ENTRIES> attributes;
+};
+
+/// Singular page table used for the singleton process
+static PageTable main_page_table;
+/// Currently active page table
+static PageTable* current_page_table = &main_page_table;
+
+static void MapPages(u32 base, u32 size, u8* memory, PageType type) {
+    LOG_DEBUG(HW_Memory, "Mapping %p onto %08X-%08X", memory, base * PAGE_SIZE, (base + size) * PAGE_SIZE);
+
+    u32 end = base + size;
+
+    while (base != end) {
+        ASSERT_MSG(base < PageTable::NUM_ENTRIES, "out of range mapping at %08X", base);
+
+        if (current_page_table->attributes[base] != PageType::Unmapped) {
+            LOG_ERROR(HW_Memory, "overlapping memory ranges at %08X", base * PAGE_SIZE);
+        }
+        current_page_table->attributes[base] = type;
+        current_page_table->pointers[base] = memory;
+
+        base += 1;
+        memory += PAGE_SIZE;
+    }
+}
+
+void InitMemoryMap() {
+    main_page_table.pointers.fill(nullptr);
+    main_page_table.attributes.fill(PageType::Unmapped);
+}
+
+void MapMemoryRegion(VAddr base, u32 size, u8* target) {
+    ASSERT_MSG((size & PAGE_MASK) == 0, "non-page aligned size: %08X", size);
+    ASSERT_MSG((base & PAGE_MASK) == 0, "non-page aligned base: %08X", base);
+    MapPages(base / PAGE_SIZE, size / PAGE_SIZE, target, PageType::Memory);
+}
+
+void MapIoRegion(VAddr base, u32 size) {
+    ASSERT_MSG((size & PAGE_MASK) == 0, "non-page aligned size: %08X", size);
+    ASSERT_MSG((base & PAGE_MASK) == 0, "non-page aligned base: %08X", base);
+    MapPages(base / PAGE_SIZE, size / PAGE_SIZE, nullptr, PageType::Special);
+}
+
+template <typename T>
+T Read(const VAddr vaddr) {
+    const u8* page_pointer = current_page_table->pointers[vaddr >> PAGE_BITS];
+    if (page_pointer) {
+        return *reinterpret_cast<const T*>(page_pointer + (vaddr & PAGE_MASK));
+    }
+
+    PageType type = current_page_table->attributes[vaddr >> PAGE_BITS];
+    switch (type) {
+    case PageType::Unmapped:
+        LOG_ERROR(HW_Memory, "unmapped Read%lu @ 0x%08X", sizeof(T) * 8, vaddr);
+        return 0;
+    case PageType::Memory:
+        ASSERT_MSG(false, "Mapped memory page without a pointer @ %08X", vaddr);
+    case PageType::Special:
+        LOG_ERROR(HW_Memory, "I/O reads aren't implemented yet @ %08X", vaddr);
+        return 0;
+    default:
+        UNREACHABLE();
+    }
+}
+
+template <typename T>
+void Write(const VAddr vaddr, const T data) {
+    u8* page_pointer = current_page_table->pointers[vaddr >> PAGE_BITS];
+    if (page_pointer) {
+        *reinterpret_cast<T*>(page_pointer + (vaddr & PAGE_MASK)) = data;
+        return;
+    }
+
+    PageType type = current_page_table->attributes[vaddr >> PAGE_BITS];
+    switch (type) {
+    case PageType::Unmapped:
+        LOG_ERROR(HW_Memory, "unmapped Write%lu 0x%08X @ 0x%08X", sizeof(data) * 8, (u32) data, vaddr);
+        return;
+    case PageType::Memory:
+        ASSERT_MSG(false, "Mapped memory page without a pointer @ %08X", vaddr);
+    case PageType::Special:
+        LOG_ERROR(HW_Memory, "I/O writes aren't implemented yet @ %08X", vaddr);
+        return;
+    default:
+        UNREACHABLE();
+    }
+}
+
+u8* GetPointer(const VAddr vaddr) {
+    u8* page_pointer = current_page_table->pointers[vaddr >> PAGE_BITS];
+    if (page_pointer) {
+        return page_pointer + (vaddr & PAGE_MASK);
+    }
+
+    LOG_ERROR(HW_Memory, "unknown GetPointer @ 0x%08x", vaddr);
+    return nullptr;
+}
+
+u8* GetPhysicalPointer(PAddr address) {
+    return GetPointer(PhysicalToVirtualAddress(address));
+}
+
+u8 Read8(const VAddr addr) {
+    return Read<u8>(addr);
+}
+
+u16 Read16(const VAddr addr) {
+    return Read<u16_le>(addr);
+}
+
+u32 Read32(const VAddr addr) {
+    return Read<u32_le>(addr);
+}
+
+u64 Read64(const VAddr addr) {
+    return Read<u64_le>(addr);
+}
+
+void Write8(const VAddr addr, const u8 data) {
+    Write<u8>(addr, data);
+}
+
+void Write16(const VAddr addr, const u16 data) {
+    Write<u16_le>(addr, data);
+}
+
+void Write32(const VAddr addr, const u32 data) {
+    Write<u32_le>(addr, data);
+}
+
+void Write64(const VAddr addr, const u64 data) {
+    Write<u64_le>(addr, data);
+}
+
+void WriteBlock(const VAddr addr, const u8* data, const size_t size) {
+    u32 offset = 0;
+    while (offset < (size & ~3)) {
+        Write32(addr + offset, *(u32*)&data[offset]);
+        offset += 4;
+    }
+
+    if (size & 2) {
+        Write16(addr + offset, *(u16*)&data[offset]);
+        offset += 2;
+    }
+
+    if (size & 1)
+        Write8(addr + offset, data[offset]);
+}
+
+} // namespace