Diff: include/opencv2/flann/allocator.h

Revision:

0:0e0631af0305

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/opencv2/flann/allocator.h	Fri Jan 29 04:53:38 2021 +0000
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+/***********************************************************************
+ * Software License Agreement (BSD License)
+ *
+ * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
+ * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
+ *
+ * THE BSD LICENSE
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *************************************************************************/
+
+#ifndef OPENCV_FLANN_ALLOCATOR_H_
+#define OPENCV_FLANN_ALLOCATOR_H_
+
+#include <stdlib.h>
+#include <stdio.h>
+
+
+namespace cvflann
+{
+
+/**
+ * Allocates (using C's malloc) a generic type T.
+ *
+ * Params:
+ *     count = number of instances to allocate.
+ * Returns: pointer (of type T*) to memory buffer
+ */
+template <typename T>
+T* allocate(size_t count = 1)
+{
+    T* mem = (T*) ::malloc(sizeof(T)*count);
+    return mem;
+}
+
+
+/**
+ * Pooled storage allocator
+ *
+ * The following routines allow for the efficient allocation of storage in
+ * small chunks from a specified pool.  Rather than allowing each structure
+ * to be freed individually, an entire pool of storage is freed at once.
+ * This method has two advantages over just using malloc() and free().  First,
+ * it is far more efficient for allocating small objects, as there is
+ * no overhead for remembering all the information needed to free each
+ * object or consolidating fragmented memory.  Second, the decision about
+ * how long to keep an object is made at the time of allocation, and there
+ * is no need to track down all the objects to free them.
+ *
+ */
+
+const size_t     WORDSIZE=16;
+const  size_t     BLOCKSIZE=8192;
+
+class PooledAllocator
+{
+    /* We maintain memory alignment to word boundaries by requiring that all
+        allocations be in multiples of the machine wordsize.  */
+    /* Size of machine word in bytes.  Must be power of 2. */
+    /* Minimum number of bytes requested at a time from	the system.  Must be multiple of WORDSIZE. */
+
+
+    int     remaining;  /* Number of bytes left in current block of storage. */
+    void*   base;     /* Pointer to base of current block of storage. */
+    void*   loc;      /* Current location in block to next allocate memory. */
+    int     blocksize;
+
+
+public:
+    int     usedMemory;
+    int     wastedMemory;
+
+    /**
+        Default constructor. Initializes a new pool.
+     */
+    PooledAllocator(int blockSize = BLOCKSIZE)
+    {
+        blocksize = blockSize;
+        remaining = 0;
+        base = NULL;
+
+        usedMemory = 0;
+        wastedMemory = 0;
+    }
+
+    /**
+     * Destructor. Frees all the memory allocated in this pool.
+     */
+    ~PooledAllocator()
+    {
+        void* prev;
+
+        while (base != NULL) {
+            prev = *((void**) base); /* Get pointer to prev block. */
+            ::free(base);
+            base = prev;
+        }
+    }
+
+    /**
+     * Returns a pointer to a piece of new memory of the given size in bytes
+     * allocated from the pool.
+     */
+    void* allocateMemory(int size)
+    {
+        int blockSize;
+
+        /* Round size up to a multiple of wordsize.  The following expression
+            only works for WORDSIZE that is a power of 2, by masking last bits of
+            incremented size to zero.
+         */
+        size = (size + (WORDSIZE - 1)) & ~(WORDSIZE - 1);
+
+        /* Check whether a new block must be allocated.  Note that the first word
+            of a block is reserved for a pointer to the previous block.
+         */
+        if (size > remaining) {
+
+            wastedMemory += remaining;
+
+            /* Allocate new storage. */
+            blockSize = (size + sizeof(void*) + (WORDSIZE-1) > BLOCKSIZE) ?
+                        size + sizeof(void*) + (WORDSIZE-1) : BLOCKSIZE;
+
+            // use the standard C malloc to allocate memory
+            void* m = ::malloc(blockSize);
+            if (!m) {
+                fprintf(stderr,"Failed to allocate memory.\n");
+                return NULL;
+            }
+
+            /* Fill first word of new block with pointer to previous block. */
+            ((void**) m)[0] = base;
+            base = m;
+
+            int shift = 0;
+            //int shift = (WORDSIZE - ( (((size_t)m) + sizeof(void*)) & (WORDSIZE-1))) & (WORDSIZE-1);
+
+            remaining = blockSize - sizeof(void*) - shift;
+            loc = ((char*)m + sizeof(void*) + shift);
+        }
+        void* rloc = loc;
+        loc = (char*)loc + size;
+        remaining -= size;
+
+        usedMemory += size;
+
+        return rloc;
+    }
+
+    /**
+     * Allocates (using this pool) a generic type T.
+     *
+     * Params:
+     *     count = number of instances to allocate.
+     * Returns: pointer (of type T*) to memory buffer
+     */
+    template <typename T>
+    T* allocate(size_t count = 1)
+    {
+        T* mem = (T*) this->allocateMemory((int)(sizeof(T)*count));
+        return mem;
+    }
+
+};
+
+}
+
+#endif //OPENCV_FLANN_ALLOCATOR_H_