Diff: utility/MemPool.cpp

Revision:

9:a156d3de5647

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/utility/MemPool.cpp	Tue Aug 27 15:01:10 2019 +0000
@@ -0,0 +1,192 @@
+/*
+ mempool.cpp - sleek implementation of a memory pool
+ Copyright (c) 2013 Norbert Truchsess <norbert.truchsess@t-online.de>
+ All rights reserved.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "MemPool.h"
+#include <string.h>
+
+#define POOLOFFSET  1
+
+struct memblock MemPool::    blocks[MEMPOOL_NUM_MEMBLOCKS + 1];
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+void MemPool::init() {
+    memset(&blocks[0], 0, sizeof(blocks));
+    blocks[POOLSTART].begin = MEMPOOL_STARTADDRESS;
+    blocks[POOLSTART].size = 0;
+    blocks[POOLSTART].nextblock = NOBLOCK;
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+memhandle MemPool::allocBlock(memaddress size) {
+    memblock*   best = NULL;
+    memhandle   cur = POOLSTART;
+    memblock*   block = &blocks[POOLSTART];
+    memaddress  bestsize = MEMPOOL_SIZE + 1;
+
+    do {
+        memhandle   next = block->nextblock;
+        memaddress  freesize = (next == NOBLOCK ? blocks[POOLSTART].begin + MEMPOOL_SIZE : blocks[next].begin) -
+            block->begin -
+            block->size;
+        if (freesize == size) {
+            best = &blocks[cur];
+            goto found;
+        }
+
+        if (freesize > size && freesize < bestsize) {
+            bestsize = freesize;
+            best = &blocks[cur];
+        }
+
+        if (next == NOBLOCK) {
+            if (best)
+                goto found;
+            else
+                goto collect;
+        }
+
+        block = &blocks[next];
+        cur = next;
+    } while (true);
+
+collect:
+    {
+        cur = POOLSTART;
+        block = &blocks[POOLSTART];
+
+        memhandle   next;
+        while ((next = block->nextblock) != NOBLOCK) {
+            memaddress      dest = block->begin + block->size;
+            memblock*       nextblock = &blocks[next];
+            memaddress*     src = &nextblock->begin;
+            if (dest != *src)
+            {
+#ifdef MEMPOOL_MEMBLOCK_MV
+                MEMPOOL_MEMBLOCK_MV(dest, *src, nextblock->size);
+#endif
+                *src = dest;
+            }
+
+            block = nextblock;
+        }
+
+        if (blocks[POOLSTART].begin + MEMPOOL_SIZE - block->begin - block->size >= size)
+            best = block;
+        else
+            goto notfound;
+    }
+
+found:
+    {
+        block = &blocks[POOLOFFSET];
+        for (cur = POOLOFFSET; cur < MEMPOOL_NUM_MEMBLOCKS + POOLOFFSET; cur++) {
+            if (block->size) {
+                block++;
+                continue;
+            }
+
+            memaddress  address = best->begin + best->size;
+#ifdef MEMBLOCK_ALLOC
+            MEMBLOCK_ALLOC(address, size);
+#endif
+            block->begin = address;
+            block->size = size;
+            block->nextblock = best->nextblock;
+            best->nextblock = cur;
+            return cur;
+        }
+    }
+
+notfound:
+    return NOBLOCK;
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+void MemPool::freeBlock(memhandle handle) {
+    if (handle == NOBLOCK)
+        return;
+
+    memblock*   b = &blocks[POOLSTART];
+
+    do {
+        memhandle   next = b->nextblock;
+        if (next == handle) {
+            memblock*   f = &blocks[next];
+#ifdef MEMBLOCK_FREE
+            MEMBLOCK_FREE(f->begin, f->size);
+#endif
+            b->nextblock = f->nextblock;
+            f->size = 0;
+            f->nextblock = NOBLOCK;
+            return;
+        }
+
+        if (next == NOBLOCK)
+            return;
+        b = &blocks[next];
+    } while (true);
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+void MemPool::resizeBlock(memhandle handle, memaddress position) {
+    memblock*   block = &blocks[handle];
+    block->begin += position;
+    block->size -= position;
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+void MemPool::resizeBlock(memhandle handle, memaddress position, memaddress size) {
+    memblock*   block = &blocks[handle];
+    block->begin += position;
+    block->size = size;
+}
+
+/**
+ * @brief
+ * @note
+ * @param
+ * @retval
+ */
+memaddress MemPool::blockSize(memhandle handle) {
+    return blocks[handle].size;
+}