decompile malloc

src/malloc.c

@@ -0,0 +1,224 @@
+#include "global.h"
+
+static void *sHeapStart;
+static u32 sHeapSize;
+
+static EWRAM_DATA struct MemBlock *head = NULL;
+static EWRAM_DATA struct MemBlock *pos = NULL;
+static EWRAM_DATA struct MemBlock *splitBlock = NULL;
+
+#define MALLOC_SYSTEM_ID 0xA3A3
+
+struct MemBlock {
+    // Whether this block is currently allocated.
+    bool16 flag;
+
+    // Magic number used for error checking. Should equal MALLOC_SYSTEM_ID.
+    u16 magic_number;
+
+    // Size of the block (not including this header struct).
+    u32 size;
+
+    // Previous block pointer. Equals sHeapStart if this is the first block.
+    struct MemBlock *prev;
+
+    // Next block pointer. Equals sHeapStart if this is the last block.
+    struct MemBlock *next;
+
+    // Data in the memory block. (Arrays of length 0 are a GNU extension.)
+    u8 data[0];
+};
+
+void PutMemBlockHeader(void *block, struct MemBlock *prev, struct MemBlock *next, u32 size)
+{
+    struct MemBlock *header = (struct MemBlock *)block;
+
+    header->flag = FALSE;
+    header->magic_number = MALLOC_SYSTEM_ID;
+    header->size = size;
+    header->prev = prev;
+    header->next = next;
+}
+
+void PutFirstMemBlockHeader(void *block, u32 size)
+{
+    PutMemBlockHeader(block, (struct MemBlock *)block, (struct MemBlock *)block, size - sizeof(struct MemBlock));
+}
+
+void *AllocInternal(void *heapStart, u32 size)
+{
+    u32 foundBlockSize;
+
+    head = (struct MemBlock *)heapStart;
+    pos = head;
+
+    // Alignment
+    if (size & 3)
+        size = 4 * ((size / 4) + 1);
+
+    for (;;) {
+        // Loop through the blocks looking for unused block that's big enough.
+
+        if (!pos->flag) {
+            foundBlockSize = pos->size;
+
+            if (foundBlockSize >= size) {
+                if (foundBlockSize - size < 2 * sizeof(struct MemBlock)) {
+                    // The block isn't much bigger than the requested size,
+                    // so just use it.
+                    pos->flag = TRUE;
+                    return pos->data;
+                } else {
+                    // The block is significantly bigger than the requested
+                    // size, so split the rest into a separate block.
+                    int splitBlockSize = foundBlockSize;
+                    splitBlockSize -= sizeof(struct MemBlock);
+                    splitBlockSize -= size;
+
+                    splitBlock = (struct MemBlock *)(pos->data + size);
+
+                    pos->flag = TRUE;
+                    pos->size = size;
+
+                    PutMemBlockHeader(splitBlock, pos, pos->next, splitBlockSize);
+
+                    pos->next = splitBlock;
+
+                    if (splitBlock->next != head)
+                        splitBlock->next->prev = splitBlock;
+                    return pos->data;
+                }
+            }
+        }
+
+        if (pos->next == head)
+        {
+            AGB_ASSERT_EX(0, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 174);
+            return NULL;
+        }
+
+        pos = pos->next;
+    }
+}
+
+void FreeInternal(void *heapStart, void *p)
+{
+    AGB_ASSERT_EX(p != NULL, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 195);
+
+    if (p) {
+        struct MemBlock *head = (struct MemBlock *)heapStart;
+        struct MemBlock *pos = (struct MemBlock *)((u8 *)p - sizeof(struct MemBlock));
+        AGB_ASSERT_EX(pos->magic_number == MALLOC_SYSTEM_ID, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 204);
+        AGB_ASSERT_EX(pos->flag == TRUE, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 205);
+        pos->flag = FALSE;
+
+        // If the freed block isn't the last one, merge with the next block
+        // if it's not in use.
+        if (pos->next != head) {
+            if (!pos->next->flag) {
+                AGB_ASSERT_EX(pos->next->magic_number == MALLOC_SYSTEM_ID, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 211);
+                pos->size += sizeof(struct MemBlock) + pos->next->size;
+                pos->next->magic_number = 0;
+                pos->next = pos->next->next;
+                if (pos->next != head)
+                    pos->next->prev = pos;
+            }
+        }
+
+        // If the freed block isn't the first one, merge with the previous block
+        // if it's not in use.
+        if (pos != head) {
+            if (!pos->prev->flag) {
+                AGB_ASSERT_EX(pos->prev->magic_number == MALLOC_SYSTEM_ID, "C:/WORK/POKeFRLG/src/pm_lgfr_ose/source/gflib/malloc.c", 228);
+
+                pos->prev->next = pos->next;
+
+                if (pos->next != head)
+                    pos->next->prev = pos->prev;
+
+                pos->magic_number = 0;
+                pos->prev->size += sizeof(struct MemBlock) + pos->size;
+            }
+        }
+    }
+}
+
+void *AllocZeroedInternal(void *heapStart, u32 size)
+{
+    void *mem = AllocInternal(heapStart, size);
+
+    if (mem != NULL) {
+        if (size & 3)
+            size = 4 * ((size / 4) + 1);
+
+        CpuFill32(0, mem, size);
+    }
+
+    return mem;
+}
+
+bool32 CheckMemBlockInternal(void *heapStart, void *pointer)
+{
+    struct MemBlock *head = (struct MemBlock *)heapStart;
+    struct MemBlock *block = (struct MemBlock *)((u8 *)pointer - sizeof(struct MemBlock));
+
+    if (block->magic_number != MALLOC_SYSTEM_ID)
+        return FALSE;
+
+    if (block->next->magic_number != MALLOC_SYSTEM_ID)
+        return FALSE;
+
+    if (block->next != head && block->next->prev != block)
+        return FALSE;
+
+    if (block->prev->magic_number != MALLOC_SYSTEM_ID)
+        return FALSE;
+
+    if (block->prev != head && block->prev->next != block)
+        return FALSE;
+
+    if (block->next != head && block->next != (struct MemBlock *)(block->data + block->size))
+        return FALSE;
+
+    return TRUE;
+}
+
+void InitHeap(void *heapStart, u32 heapSize)
+{
+    sHeapStart = heapStart;
+    sHeapSize = heapSize;
+    PutFirstMemBlockHeader(heapStart, heapSize);
+}
+
+void *Alloc(u32 size)
+{
+    AllocInternal(sHeapStart, size);
+}
+
+void *AllocZeroed(u32 size)
+{
+    AllocZeroedInternal(sHeapStart, size);
+}
+
+void Free(void *pointer)
+{
+    FreeInternal(sHeapStart, pointer);
+}
+
+bool32 CheckMemBlock(void *pointer)
+{
+    return CheckMemBlockInternal(sHeapStart, pointer);
+}
+
+bool32 CheckHeap()
+{
+    struct MemBlock *pos = (struct MemBlock *)sHeapStart;
+
+    do {
+        if (!CheckMemBlockInternal(sHeapStart, pos->data))
+            return FALSE;
+        pos = pos->next;
+    } while (pos != (struct MemBlock *)sHeapStart);
+
+    return TRUE;
+}