/**************************************************************************** * mm/mm_heap/mm_malloc.c * * Copyright (C) 2007, 2009, 2013-2014, 2017 Gregory Nutt. All rights * reserved. * Author: Gregory Nutt * * 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. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 * COPYRIGHT OWNER OR CONTRIBUTORS 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ #ifndef NULL # define NULL ((void *)0) #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: mm_malloc * * Description: * Find the smallest chunk that satisfies the request. Take the memory from * that chunk, save the remaining, smaller chunk (if any). * * 8-byte alignment of the allocated data is assured. * ****************************************************************************/ FAR void *mm_malloc(FAR struct mm_heap_s *heap, size_t size) { FAR struct mm_freenode_s *node; size_t alignsize; void *ret = NULL; int ndx; /* Ignore zero-length allocations */ if (size < 1) { return NULL; } /* Adjust the size to account for (1) the size of the allocated node and * (2) to make sure that it is an even multiple of our granule size. */ alignsize = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE); DEBUGASSERT(alignsize >= size); /* Check for integer overflow */ DEBUGASSERT(alignsize >= MM_MIN_CHUNK); DEBUGASSERT(alignsize >= SIZEOF_MM_FREENODE); /* We need to hold the MM semaphore while we muck with the nodelist. */ mm_takesemaphore(heap); /* Get the location in the node list to start the search. Special case * really big allocations */ if (alignsize >= MM_MAX_CHUNK) { ndx = MM_NNODES - 1; } else { /* Convert the request size into a nodelist index */ ndx = mm_size2ndx(alignsize); } /* Search for a large enough chunk in the list of nodes. This list is * ordered by size, but will have occasional zero sized nodes as we visit * other mm_nodelist[] entries. */ for (node = heap->mm_nodelist[ndx].flink; node && node->size < alignsize; node = node->flink) { DEBUGASSERT(node->blink->flink == node); } /* If we found a node with non-zero size, then this is one to use. Since * the list is ordered, we know that is must be best fitting chunk * available. */ if (node) { FAR struct mm_freenode_s *remainder; FAR struct mm_freenode_s *next; size_t remaining; /* Remove the node. There must be a predecessor, but there may not be * a successor node. */ DEBUGASSERT(node->blink); node->blink->flink = node->flink; if (node->flink) { node->flink->blink = node->blink; } /* Check if we have to split the free node into one of the allocated * size and another smaller freenode. In some cases, the remaining * bytes can be smaller (they may be SIZEOF_MM_ALLOCNODE). In that * case, we will just carry the few wasted bytes at the end of the * allocation. */ remaining = node->size - alignsize; if (remaining >= SIZEOF_MM_FREENODE) { /* Get a pointer to the next node in physical memory */ next = (FAR struct mm_freenode_s *)(((FAR char *)node) + node->size); /* Create the remainder node */ remainder = (FAR struct mm_freenode_s *) (((FAR char *)node) + alignsize); remainder->size = remaining; remainder->preceding = alignsize; /* Adjust the size of the node under consideration */ node->size = alignsize; /* Adjust the 'preceding' size of the (old) next node, preserving * the allocated flag. */ next->preceding = remaining | (next->preceding & MM_ALLOC_BIT); /* Add the remainder back into the nodelist */ mm_addfreechunk(heap, remainder); } /* Handle the case of an exact size match */ node->preceding |= MM_ALLOC_BIT; ret = (void *)((FAR char *)node + SIZEOF_MM_ALLOCNODE); } DEBUGASSERT(ret == NULL || mm_heapmember(heap, ret)); mm_givesemaphore(heap); #ifdef CONFIG_MM_FILL_ALLOCATIONS if (ret) { memset(ret, 0xaa, alignsize - SIZEOF_MM_ALLOCNODE); } #endif /* If CONFIG_DEBUG_MM is defined, then output the result of the allocation * to the SYSLOG. */ #ifdef CONFIG_DEBUG_MM if (!ret) { mwarn("WARNING: Allocation failed, size %d\n", alignsize); } else { minfo("Allocated %p, size %d\n", ret, alignsize); } #endif return ret; }