Add linearMemAlign() (current implementation sucks)

diff --git a/libctru/include/3ds/linear.h b/libctru/include/3ds/linear.h
index ae4c915c71c20a70cb9df87d6ceca28601254002..8fe2c7d805d807be28eb59609e6e0932ff601bc2 100644 (file)
--- a/libctru/include/3ds/linear.h
+++ b/libctru/include/3ds/linear.h
@@ -1,7 +1,8 @@
 #pragma once
 
 // Functions for allocating/deallocating memory from linear heap
-void* linearAlloc(size_t size);
-void* linearRealloc(void* mem, size_t size);
+void* linearAlloc(size_t size); // returns a 16-byte aligned address
+void* linearMemAlign(size_t size, size_t alignment); // WARNING: wastes 'alignment' bytes
+void* linearRealloc(void* mem, size_t size); // not implemented yet
 void linearFree(void* mem);
 u32 linearSpaceFree(); // get free linear space in bytes

diff --git a/libctru/source/allocator/linear.cpp b/libctru/source/allocator/linear.cpp
index 83d1143ae01d7cdbc0c650460e24b6a6d732a932..0a47275b8a4dc01ce66455b42f2224c9f403447a 100644 (file)
--- a/libctru/source/allocator/linear.cpp
+++ b/libctru/source/allocator/linear.cpp
@@ -16,24 +16,44 @@ static bool linearInit()
        return false;
 }
 
-void* linearAlloc(size_t size)
+void* linearMemAlign(size_t size, size_t alignment)
 {
+       // Enforce minimum alignment
+       if (alignment < 16)
+               alignment = 16;
+
+       // Convert alignment to shift amount
+       int shift;
+       for (shift = 4; shift < 32; shift ++)
+       {
+               if ((1U<<shift) == alignment)
+                       break;
+       }
+       if (shift == 32) // Invalid alignment
+               return nullptr;
+
        // Initialize the pool if it is not ready
        if (!sLinearPool.Ready() && !linearInit())
                return nullptr;
 
        // Reserve memory for MemChunk structure
-       size += 16;
+       size += alignment;
 
        // Allocate the chunk
        MemChunk chunk;
-       if (!sLinearPool.Allocate(chunk, size, 4)) // 16-byte alignment
+       if (!sLinearPool.Allocate(chunk, size, shift))
                return nullptr;
 
        // Copy the MemChunk structure and return memory
        auto addr = chunk.addr;
        *(MemChunk*)addr = chunk;
-       return addr + 16;
+       *(u32*)(addr + alignment - sizeof(u32)) = alignment;
+       return addr + alignment;
+}
+
+void* linearAlloc(size_t size)
+{
+       return linearMemAlign(size, 16);
 }
 
 void* linearRealloc(void* mem, size_t size)
@@ -45,7 +65,8 @@ void* linearRealloc(void* mem, size_t size)
 void linearFree(void* mem)
 {
        // Find MemChunk structure and free the chunk
-       auto pChunk = (MemChunk*)((u8*)mem - 16);
+       u32 alignment = *((u32*)mem - 1);
+       auto pChunk = (MemChunk*)((u8*)mem - alignment);
        sLinearPool.Deallocate(*pChunk);
 }