mem_pool.h

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#pragma once
#include <3ds.h>

struct MemChunk
{
    u8* addr;
    u32 size;
};

struct MemBlock
{
    MemBlock *prev, *next;
    u8* base;
    u32 size;

    static MemBlock* Create(u8* base, u32 size)
    {
        auto b = (MemBlock*)malloc(sizeof(MemBlock));
        if (!b) return nullptr;
        b->prev = nullptr;
        b->next = nullptr;
        b->base = base;
        b->size = size;
        return b;
    }
};

struct MemPool
{
    MemBlock *first, *last;

    bool Ready() { return first != nullptr; }

    void AddBlock(MemBlock* blk)
    {
        blk->prev = last;
        if (last) last->next = blk;
        if (!first) first = blk;
        last = blk;
    }

    void DelBlock(MemBlock* b)
    {
        auto prev = b->prev, &pNext = prev ? prev->next : first;
        auto next = b->next, &nPrev = next ? next->prev : last;
        pNext = next;
        nPrev = prev;
        free(b);
    }

    void InsertBefore(MemBlock* b, MemBlock* p)
    {
        auto prev = b->prev, &pNext = prev ? prev->next : first;
        b->prev = p;
        p->next = b;
        p->prev = prev;
        pNext = p;
    }

    void InsertAfter(MemBlock* b, MemBlock* n)
    {
        auto next = b->next, &nPrev = next ? next->prev : last;
        b->next = n;
        n->prev = b;
        n->next = next;
        nPrev = n;
    }

    //void CoalesceLeft(MemBlock* b);
    void CoalesceRight(MemBlock* b);

    bool Allocate(MemChunk& chunk, u32 size, int align);
    void Deallocate(const MemChunk& chunk);

    void Destroy()
    {
        MemBlock* next = nullptr;
        for (auto b = first; b; b = next)
        {
            next = b->next;
            free(b);
        }
        first = nullptr;
        last = nullptr;
    }

    //void Dump(const char* title);
    u32 GetFreeSpace();
};