multimalloc.h

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#ifndef _MULTIMALLOC_H_
#define _MULTIMALLOC_H_

#include <assert.h>

#include <fstream.h>


#include "dynarray.h"
#include "stack.h"


template <class SuperHeap>
class MultiMalloc : public SuperHeap {
public:


        MultiMalloc (void) {
                //f.open ("multimalloc.log");
        }

        ~MultiMalloc (void) {
                //f.close ();
        }

        // Sets ptr to a list of up to num objects of size sz
        // and returns how many free objects ptr points to.
        int multimalloc (int num, size_t sz, void *& ptr)
        {
                //f << "multimalloc from " << this << endl << flush;
                // printf ("multimalloc\n");
                assert (num > 0);
                if (stk.empty()) {
#if 0
                        //f << "malloc " << num << ", " << sz << "\n" << flush;
                        ptr = SuperHeap::malloc (sz);
                        assert (size(ptr) >= sz);
                        assert (sz >= sizeof(FreeObject *));
                        FreeObject * p = (FreeObject *) ptr;
                        for (int i = 1; i < num; i++) {
                                p->next = (FreeObject *) SuperHeap::malloc (sz);
                                p = p->next;
                                assert (size(p) >= sz);
                        }
                        p->next = NULL;
#else
                        size_t sz1 = align(sz + sizeof(double));
                        ptr = SuperHeap::malloc (num * sz1); // Allow room for size & thread info.
                        ptr = (double *) ptr + 1;
                        FreeObject * p = (FreeObject *) ptr;
                        for (int i = 0; i < num - 1; i++) {
                                size(p) = sz;
                                FreeObject * next = (FreeObject *) (((unsigned long) p) + sz1);
                                p->next = next;
                                p = p->next;
                        }
                        size(p) = sz;
                        p->next = NULL;
                        assert (size(p) + ((unsigned long) p) <= ((unsigned long) ptr + num * sz1));
#endif

#ifndef NDEBUG
                        p = (FreeObject *) ptr;
                        int c = 0;
                        while (p != NULL) {
                                c++;
                                p = p->next;
                        }
                        assert (c == num);
#endif
                        return num;
                } else {
                        // Pop off some memory from the stack.
                        assert (!stk.empty());
                        np v = stk.pop();
                        // JUST FOR CHECKING --
                        assert (v.num == num);
                        ptr = v.ptr;
                        assert (v.num > 0);
                        assert (size(ptr) >= sz);
                        //f << "multimalloc " << v.num << ", " << sz << "\n" << flush;
                        return v.num;
                }
        }

        // Frees all num items pointed to by ptr.
        void multifree (int num, void * ptr)
        {
                // printf ("multifree\n");
                np v;
                //f << "multifree " << num << ", size = " << size(ptr) << "\n" << flush;
                v.num = num;
                v.ptr = ptr;
                stk.push (v);
        }

private:

        MultiMalloc (const MultiMalloc&);
        MultiMalloc& operator=(const MultiMalloc&);

        class np {
        public:
                int num;
                void * ptr;
        };

        class FreeObject {
        public:
                FreeObject * next;
        };

        void * malloc (size_t);
        void free (void *);

        Stack<np, DynArray<np> > stk;
        //ofstream f;

        static inline size_t align (size_t sz) {
                return (sz + (sizeof(double) - 1)) & ~(sizeof(double) - 1);
        }

};


#endif

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