930 lines
30 KiB
C++
930 lines
30 KiB
C++
/* ----------------------------------------------------------------------------
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* umm_malloc.c - a memory allocator for embedded systems (microcontrollers)
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 Ralph Hempel
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* ----------------------------------------------------------------------------
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*
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* Note: this version is significantly modified from the version
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* distributed by Ralph Hempel. In particular, block numbers are
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* 32 bits in this version.
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* ----------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stddef.h>
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#include <string.h>
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#include <stdbool.h>
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#include <math.h>
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#include "umm-malloc.hpp"
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/*
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* --------------------------------------------------------------------------
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* UMM_BEST_FIT (default)
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*
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* Set this if you want to use a best-fit algorithm for allocating new blocks.
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* On by default, turned off by UMM_FIRST_FIT
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*
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* UMM_FIRST_FIT
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*
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* Set this if you want to use a first-fit algorithm for allocating new blocks.
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* Faster than UMM_BEST_FIT but can result in higher fragmentation.
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*
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* ----------------------------------------------------------------------------
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*/
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#define UMM_BEST_FIT
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#undef UMM_FIRST_FIT
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/*
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* --------------------------------------------------------------------------
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*
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* Three macros to make it easier to protect the memory allocator in a
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* multitasking system. You should set these macros up to use whatever your
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* system uses for this purpose. You can disable interrupts entirely, or just
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* disable task switching - it's up to you
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*
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* NOTE WELL that these macros MUST be allowed to nest, because umm_free() is
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* called from within umm_malloc()
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*
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* --------------------------------------------------------------------------
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*/
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#define UMM_CRITICAL_DECL(tag)
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#define UMM_CRITICAL_ENTRY(tag)
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#define UMM_CRITICAL_EXIT(tag)
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/*
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* --------------------------------------------------------------------------
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*
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* Debug Logging.
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*
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* --------------------------------------------------------------------------
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*/
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// #define DBGLOG(format, ...) { fprintf(stderr, format,##__VA_ARGS__); fflush(stderr); }
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#define DBGLOG(format, ...)
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/* ------------------------------------------------------------------------- */
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typedef struct umm_ptr_t {
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uint32_t next;
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uint32_t prev;
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} umm_ptr;
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typedef struct umm_block_t {
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union {
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umm_ptr used;
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} header;
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union {
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umm_ptr free;
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uint8_t data[8];
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} body;
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} umm_block;
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#define UMM_FREELIST_MASK ((uint32_t)(0x80000000))
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#define UMM_BLOCKNO_MASK ((uint32_t)(0x7FFFFFFF))
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/* ------------------------------------------------------------------------- */
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struct umm_heap_config {
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umm_block *pheap;
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size_t heap_size;
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uint32_t numblocks;
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};
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static struct umm_heap_config umm_heap_current;
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#define UMM_HEAP (umm_heap_current.pheap)
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#define UMM_HEAPSIZE (umm_heap_current.heap_size)
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#define UMM_NUMBLOCKS (umm_heap_current.numblocks)
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#define UMM_BLOCKSIZE (sizeof(umm_block))
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#define UMM_BLOCK_LAST (UMM_NUMBLOCKS - 1)
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/* -------------------------------------------------------------------------
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* These macros evaluate to the address of the block and data respectively
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*/
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#define UMM_BLOCK(b) (UMM_HEAP[b])
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#define UMM_DATA(b) (UMM_BLOCK(b).body.data)
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/* -------------------------------------------------------------------------
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* These macros evaluate to the index of the block - NOT the address!!!
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*/
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#define UMM_NBLOCK(b) (UMM_BLOCK(b).header.used.next)
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#define UMM_PBLOCK(b) (UMM_BLOCK(b).header.used.prev)
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#define UMM_NFREE(b) (UMM_BLOCK(b).body.free.next)
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#define UMM_PFREE(b) (UMM_BLOCK(b).body.free.prev)
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/* ----------------------------------------------------------------------------
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* One of the coolest things about this little library is that it's VERY
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* easy to get debug information about the memory heap by simply iterating
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* through all of the memory blocks.
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*
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* As you go through all the blocks, you can check to see if it's a free
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* block by looking at the high order bit of the next block index. You can
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* also see how big the block is by subtracting the next block index from
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* the current block number.
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*
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* The umm_info function does all of that and makes the results available
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* in the ummHeapInfo structure.
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* ----------------------------------------------------------------------------
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*/
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typedef struct UMM_HEAP_INFO_t {
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unsigned int totalEntries;
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unsigned int usedEntries;
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unsigned int freeEntries;
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unsigned int totalBlocks;
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unsigned int usedBlocks;
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unsigned int freeBlocks;
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unsigned int freeBlocksSquared;
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unsigned int maxFreeContiguousBlocks;
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int usage_metric;
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int fragmentation_metric;
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}
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UMM_HEAP_INFO;
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static UMM_HEAP_INFO ummHeapInfo;
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static void compute_usage_metric(void)
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{
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if (0 == ummHeapInfo.freeBlocks) {
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ummHeapInfo.usage_metric = -1; // No free blocks!
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} else {
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ummHeapInfo.usage_metric = (int)((ummHeapInfo.usedBlocks * 100) / (ummHeapInfo.freeBlocks));
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}
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}
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static void compute_fragmentation_metric(void)
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{
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if (0 == ummHeapInfo.freeBlocks) {
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ummHeapInfo.fragmentation_metric = 0; // No free blocks ... so no fragmentation either!
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} else {
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ummHeapInfo.fragmentation_metric = 100 - (((uint32_t)(sqrtf(ummHeapInfo.freeBlocksSquared)) * 100) / (ummHeapInfo.freeBlocks));
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}
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}
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#define DBGLOG_32_BIT_PTR(x) ((uint32_t)(((uintptr_t)(x)) & 0xffffffff))
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void umm_info() {
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uint32_t blockNo = 0;
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UMM_CRITICAL_DECL(id_info);
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/* Protect the critical section... */
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UMM_CRITICAL_ENTRY(id_info);
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/*
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* Clear out all of the entries in the ummHeapInfo structure before doing
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* any calculations..
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*/
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memset(&ummHeapInfo, 0, sizeof(ummHeapInfo));
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DBGLOG("\n");
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DBGLOG("+----------+-------+--------+--------+-------+--------+--------+\n");
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DBGLOG("|0x%08x|B %5i|NB %5i|PB %5i|Z %5i|NF %5i|PF %5i|\n",
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DBGLOG_32_BIT_PTR(&UMM_BLOCK(blockNo)),
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blockNo,
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UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK,
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UMM_PBLOCK(blockNo),
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(UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK) - blockNo,
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UMM_NFREE(blockNo),
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UMM_PFREE(blockNo));
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/*
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* Now loop through the block lists, and keep track of the number and size
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* of used and free blocks. The terminating condition is an nb pointer with
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* a value of zero...
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*/
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blockNo = UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK;
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while (UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK) {
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size_t curBlocks = (UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK) - blockNo;
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++ummHeapInfo.totalEntries;
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ummHeapInfo.totalBlocks += curBlocks;
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/* Is this a free block? */
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if (UMM_NBLOCK(blockNo) & UMM_FREELIST_MASK) {
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++ummHeapInfo.freeEntries;
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ummHeapInfo.freeBlocks += curBlocks;
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ummHeapInfo.freeBlocksSquared += (curBlocks * curBlocks);
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if (ummHeapInfo.maxFreeContiguousBlocks < curBlocks) {
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ummHeapInfo.maxFreeContiguousBlocks = curBlocks;
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}
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DBGLOG("|0x%08x|B %5i|NB %5i|PB %5i|Z %5u|NF %5i|PF %5i|\n",
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DBGLOG_32_BIT_PTR(&UMM_BLOCK(blockNo)),
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blockNo,
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UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK,
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UMM_PBLOCK(blockNo),
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(uint32_t)curBlocks,
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UMM_NFREE(blockNo),
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UMM_PFREE(blockNo));
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} else {
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++ummHeapInfo.usedEntries;
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ummHeapInfo.usedBlocks += curBlocks;
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DBGLOG("|0x%08x|B %5i|NB %5i|PB %5i|Z %5u| |\n",
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DBGLOG_32_BIT_PTR(&UMM_BLOCK(blockNo)),
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blockNo,
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UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK,
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UMM_PBLOCK(blockNo),
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(uint32_t)curBlocks);
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}
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blockNo = UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK;
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}
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/*
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* The very last block is used as a placeholder to indicate that
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* there are no more blocks in the heap, so it cannot be used
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* for anything - at the same time, the size of this block must
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* ALWAYS be exactly 1 !
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*/
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DBGLOG("|0x%08x|B %5i|NB %5i|PB %5i|Z %5i|NF %5i|PF %5i|\n",
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DBGLOG_32_BIT_PTR(&UMM_BLOCK(blockNo)),
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blockNo,
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UMM_NBLOCK(blockNo) & UMM_BLOCKNO_MASK,
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UMM_PBLOCK(blockNo),
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UMM_NUMBLOCKS - blockNo,
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UMM_NFREE(blockNo),
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UMM_PFREE(blockNo));
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DBGLOG("+----------+-------+--------+--------+-------+--------+--------+\n");
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DBGLOG("Total Entries %5i Used Entries %5i Free Entries %5i\n",
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ummHeapInfo.totalEntries,
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ummHeapInfo.usedEntries,
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ummHeapInfo.freeEntries);
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DBGLOG("Total Blocks %5i Used Blocks %5i Free Blocks %5i\n",
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ummHeapInfo.totalBlocks,
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ummHeapInfo.usedBlocks,
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ummHeapInfo.freeBlocks);
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DBGLOG("+--------------------------------------------------------------+\n");
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compute_usage_metric();
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DBGLOG("Usage Metric: %5i\n", ummHeapInfo.usage_metric);
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compute_fragmentation_metric();
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DBGLOG("Fragmentation Metric: %5i\n", ummHeapInfo.fragmentation_metric);
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DBGLOG("+--------------------------------------------------------------+\n");
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/* Release the critical section... */
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UMM_CRITICAL_EXIT(id_info);
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}
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/* ------------------------------------------------------------------------ */
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static uint32_t umm_blocks(size_t size) {
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/*
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* The calculation of the block size is not too difficult, but there are
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* a few little things that we need to be mindful of.
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*
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* When a block removed from the free list, the space used by the free
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* pointers is available for data. That's what the first calculation
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* of size is doing.
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*
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* We don't check for the special case of (size == 0) here as this needs
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* special handling in the caller depending on context. For example when we
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* realloc() a block to size 0 it should simply be freed.
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*
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* We do NOT need to check for allocating more blocks than the heap can
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* possibly hold - the allocator figures this out for us.
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*
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* There are only two cases left to consider:
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*
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* 1. (size <= body) Obviously this is just one block
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* 2. (blocks > (2^15)) This should return ((2^15)) to force a
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* failure when the allocator runs
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*
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* If the requested size is greater that 32677-2 blocks (max block index
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* minus the overhead of the top and bottom bookkeeping blocks) then we
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* will return an incorrectly truncated value when the result is cast to
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* a uint32_t.
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*/
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if (size <= (sizeof(((umm_block *)0)->body))) {
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return 1;
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}
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/*
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* If it's for more than that, then we need to figure out the number of
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* additional whole blocks the size of an umm_block are required, so
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* reduce the size request by the number of bytes in the body of the
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* first block.
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*/
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size -= (sizeof(((umm_block *)0)->body));
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/* NOTE WELL that we take advantage of the fact that INT16_MAX is the
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* number of blocks that we can index in 15 bits :-)
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*
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* The below expression looks wierd, but it's right. Assuming body
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* size of 4 bytes and a block size of 8 bytes:
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*
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* BYTES (BYTES-BODY) (BYTES-BODY-1)/BLOCKSIZE BLOCKS
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* 1 n/a n/a 1
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* 5 1 0 2
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* 12 8 0 2
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* 13 9 1 3
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*/
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size_t blocks = (2 + ((size-1) / (UMM_BLOCKSIZE)));
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if (blocks > (INT16_MAX)) {
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blocks = INT16_MAX;
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}
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return (uint32_t)blocks;
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}
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/* ------------------------------------------------------------------------ */
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/*
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* Split the block `c` into two blocks: `c` and `c + blocks`.
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*
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* - `new_freemask` should be `0` if `c + blocks` used, or `UMM_FREELIST_MASK`
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* otherwise.
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*
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* Note that free pointers are NOT modified by this function.
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*/
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static void umm_split_block(uint32_t c,
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uint32_t blocks,
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uint32_t new_freemask) {
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UMM_NBLOCK(c + blocks) = (UMM_NBLOCK(c) & UMM_BLOCKNO_MASK) | new_freemask;
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UMM_PBLOCK(c + blocks) = c;
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UMM_PBLOCK(UMM_NBLOCK(c) & UMM_BLOCKNO_MASK) = (c + blocks);
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UMM_NBLOCK(c) = (c + blocks);
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}
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/* ------------------------------------------------------------------------ */
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static void umm_disconnect_from_free_list(uint32_t c) {
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/* Disconnect this block from the FREE list */
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UMM_NFREE(UMM_PFREE(c)) = UMM_NFREE(c);
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UMM_PFREE(UMM_NFREE(c)) = UMM_PFREE(c);
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/* And clear the free block indicator */
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UMM_NBLOCK(c) &= (~UMM_FREELIST_MASK);
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}
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/* ------------------------------------------------------------------------
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* The umm_assimilate_up() function does not assume that UMM_NBLOCK(c)
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* has the UMM_FREELIST_MASK bit set. It only assimilates up if the
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* next block is free.
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*/
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static void umm_assimilate_up(uint32_t c) {
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if (UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_FREELIST_MASK) {
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/*
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* The next block is a free block, so assimilate up and remove it from
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* the free list
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*/
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DBGLOG("Assimilate up to next block, which is FREE\n");
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/* Disconnect the next block from the FREE list */
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umm_disconnect_from_free_list(UMM_NBLOCK(c));
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/* Assimilate the next block with this one */
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UMM_PBLOCK(UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_BLOCKNO_MASK) = c;
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UMM_NBLOCK(c) = UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_BLOCKNO_MASK;
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}
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}
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/* ------------------------------------------------------------------------
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* The umm_assimilate_down() function assumes that UMM_NBLOCK(c) does NOT
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* have the UMM_FREELIST_MASK bit set. In other words, try to assimilate
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* up before assimilating down.
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*/
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static uint32_t umm_assimilate_down(uint32_t c, uint32_t freemask) {
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// We are going to assimilate down to the previous block because
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// it was free, so remove it from the fragmentation metric
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UMM_NBLOCK(UMM_PBLOCK(c)) = UMM_NBLOCK(c) | freemask;
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UMM_PBLOCK(UMM_NBLOCK(c)) = UMM_PBLOCK(c);
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return UMM_PBLOCK(c);
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}
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/* ------------------------------------------------------------------------- */
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void umm_init_heap(void *ptr, size_t size)
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{
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/* init heap pointer and size, and memset it to 0 */
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UMM_HEAP = (umm_block *)ptr;
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UMM_HEAPSIZE = size;
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UMM_NUMBLOCKS = (UMM_HEAPSIZE / UMM_BLOCKSIZE);
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memset(UMM_HEAP, 0x00, UMM_HEAPSIZE);
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/* Set up umm_block[0], which just points to umm_block[1] */
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UMM_NBLOCK(0) = 1;
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UMM_NFREE(0) = 1;
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UMM_PFREE(0) = 1;
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/*
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* Now, we need to set the whole heap space as a huge free block. We should
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* not touch umm_block[0], since it's special: umm_block[0] is the head of
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* the free block list. It's a part of the heap invariant.
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*
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* See the detailed explanation at the beginning of the file.
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*
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* umm_block[1] has pointers:
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*
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* - next `umm_block`: the last one umm_block[n]
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* - prev `umm_block`: umm_block[0]
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*
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* Plus, it's a free `umm_block`, so we need to apply `UMM_FREELIST_MASK`
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*
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* And it's the last free block, so the next free block is 0 which marks
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* the end of the list. The previous block and free block pointer are 0
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* too, there is no need to initialize these values due to the init code
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* that memsets the entire umm_ space to 0.
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*/
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UMM_NBLOCK(1) = UMM_BLOCK_LAST | UMM_FREELIST_MASK;
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/*
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* Last umm_block[n] has the next block index at 0, meaning it's
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* the end of the list, and the previous block is umm_block[1].
|
|
*
|
|
* The last block is a special block and can never be part of the
|
|
* free list, so its pointers are left at 0 too.
|
|
*/
|
|
|
|
UMM_PBLOCK(UMM_BLOCK_LAST) = 1;
|
|
|
|
// DBGLOG(true, "nblock(0) %04x pblock(0) %04x nfree(0) %04x pfree(0) %04x\n", UMM_NBLOCK(0) & UMM_BLOCKNO_MASK, UMM_PBLOCK(0), UMM_NFREE(0), UMM_PFREE(0));
|
|
// DBGLOG(true, "nblock(1) %04x pblock(1) %04x nfree(1) %04x pfree(1) %04x\n", UMM_NBLOCK(1) & UMM_BLOCKNO_MASK, UMM_PBLOCK(1), UMM_NFREE(1), UMM_PFREE(1));
|
|
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------
|
|
* Must be called only from within critical sections guarded by
|
|
* UMM_CRITICAL_ENTRY(id) and UMM_CRITICAL_EXIT(id).
|
|
*/
|
|
|
|
static void umm_free_core(void *ptr) {
|
|
|
|
uint32_t c;
|
|
|
|
/*
|
|
* FIXME: At some point it might be a good idea to add a check to make sure
|
|
* that the pointer we're being asked to free up is actually within
|
|
* the umm_heap!
|
|
*
|
|
*/
|
|
|
|
/* Figure out which block we're in. Note the use of truncated division... */
|
|
|
|
c = (((uint8_t *)ptr) - (uint8_t *)(&(UMM_HEAP[0]))) / UMM_BLOCKSIZE;
|
|
|
|
DBGLOG("Freeing block %6i\n", c);
|
|
|
|
/* Now let's assimilate this block with the next one if possible. */
|
|
|
|
umm_assimilate_up(c);
|
|
|
|
/* Then assimilate with the previous block if possible */
|
|
|
|
if (UMM_NBLOCK(UMM_PBLOCK(c)) & UMM_FREELIST_MASK) {
|
|
|
|
DBGLOG("Assimilate down to previous block, which is FREE\n");
|
|
|
|
c = umm_assimilate_down(c, UMM_FREELIST_MASK);
|
|
} else {
|
|
/*
|
|
* The previous block is not a free block, so add this one to the head
|
|
* of the free list
|
|
*/
|
|
DBGLOG("Just add to head of free list\n");
|
|
|
|
UMM_PFREE(UMM_NFREE(0)) = c;
|
|
UMM_NFREE(c) = UMM_NFREE(0);
|
|
UMM_PFREE(c) = 0;
|
|
UMM_NFREE(0) = c;
|
|
|
|
UMM_NBLOCK(c) |= UMM_FREELIST_MASK;
|
|
}
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------ */
|
|
|
|
void umm_free(void *ptr) {
|
|
UMM_CRITICAL_DECL(id_free);
|
|
|
|
/* If we're being asked to free a NULL pointer, well that's just silly! */
|
|
|
|
if ((void *)0 == ptr) {
|
|
DBGLOG("free a null pointer -> do nothing\n");
|
|
|
|
return;
|
|
}
|
|
|
|
/* Free the memory withing a protected critical section */
|
|
|
|
UMM_CRITICAL_ENTRY(id_free);
|
|
|
|
umm_free_core(ptr);
|
|
|
|
UMM_CRITICAL_EXIT(id_free);
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------
|
|
* Must be called only from within critical sections guarded by
|
|
* UMM_CRITICAL_ENTRY(id) and UMM_CRITICAL_EXIT(id).
|
|
*/
|
|
|
|
static void *umm_malloc_core(size_t size) {
|
|
uint32_t blocks;
|
|
uint32_t blockSize = 0;
|
|
|
|
uint32_t bestSize;
|
|
uint32_t bestBlock;
|
|
|
|
uint32_t cf;
|
|
|
|
blocks = umm_blocks(size);
|
|
|
|
/*
|
|
* Now we can scan through the free list until we find a space that's big
|
|
* enough to hold the number of blocks we need.
|
|
*
|
|
* This part may be customized to be a best-fit, worst-fit, or first-fit
|
|
* algorithm
|
|
*/
|
|
|
|
cf = UMM_NFREE(0);
|
|
|
|
bestBlock = UMM_NFREE(0);
|
|
bestSize = 0x7FFFFFFF;
|
|
|
|
while (cf) {
|
|
blockSize = (UMM_NBLOCK(cf) & UMM_BLOCKNO_MASK) - cf;
|
|
|
|
DBGLOG("Looking at block %6i size %6i\n", cf, blockSize);
|
|
|
|
#if defined UMM_BEST_FIT
|
|
if ((blockSize >= blocks) && (blockSize < bestSize)) {
|
|
bestBlock = cf;
|
|
bestSize = blockSize;
|
|
}
|
|
#elif defined UMM_FIRST_FIT
|
|
/* This is the first block that fits! */
|
|
if ((blockSize >= blocks)) {
|
|
break;
|
|
}
|
|
#else
|
|
#error "No UMM_*_FIT is defined - check umm_malloc_cfg.h"
|
|
#endif
|
|
|
|
cf = UMM_NFREE(cf);
|
|
}
|
|
|
|
if (0x7FFFFFFF != bestSize) {
|
|
cf = bestBlock;
|
|
blockSize = bestSize;
|
|
}
|
|
|
|
if (UMM_NBLOCK(cf) & UMM_BLOCKNO_MASK && blockSize >= blocks) {
|
|
|
|
/*
|
|
* This is an existing block in the memory heap, we just need to split off
|
|
* what we need, unlink it from the free list and mark it as in use, and
|
|
* link the rest of the block back into the freelist as if it was a new
|
|
* block on the free list...
|
|
*/
|
|
|
|
if (blockSize == blocks) {
|
|
/* It's an exact fit and we don't neet to split off a block. */
|
|
DBGLOG("Allocating %6i blocks starting at %6i - exact\n", blocks, cf);
|
|
|
|
/* Disconnect this block from the FREE list */
|
|
|
|
umm_disconnect_from_free_list(cf);
|
|
} else {
|
|
|
|
/* It's not an exact fit and we need to split off a block. */
|
|
DBGLOG("Allocating %6i blocks starting at %6i - existing\n", blocks, cf);
|
|
|
|
/*
|
|
* split current free block `cf` into two blocks. The first one will be
|
|
* returned to user, so it's not free, and the second one will be free.
|
|
*/
|
|
umm_split_block(cf, blocks, UMM_FREELIST_MASK /*new block is free*/);
|
|
|
|
/*
|
|
* `umm_split_block()` does not update the free pointers (it affects
|
|
* only free flags), but effectively we've just moved beginning of the
|
|
* free block from `cf` to `cf + blocks`. So we have to adjust pointers
|
|
* to and from adjacent free blocks.
|
|
*/
|
|
|
|
/* previous free block */
|
|
UMM_NFREE(UMM_PFREE(cf)) = cf + blocks;
|
|
UMM_PFREE(cf + blocks) = UMM_PFREE(cf);
|
|
|
|
/* next free block */
|
|
UMM_PFREE(UMM_NFREE(cf)) = cf + blocks;
|
|
UMM_NFREE(cf + blocks) = UMM_NFREE(cf);
|
|
}
|
|
|
|
} else {
|
|
/* Out of memory */
|
|
|
|
DBGLOG("Can't allocate %5i blocks\n", blocks);
|
|
|
|
return (void *)NULL;
|
|
}
|
|
|
|
return (void *)&UMM_DATA(cf);
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------ */
|
|
|
|
void *umm_malloc(size_t size) {
|
|
UMM_CRITICAL_DECL(id_malloc);
|
|
|
|
void *ptr = NULL;
|
|
|
|
/*
|
|
* the very first thing we do is figure out if we're being asked to allocate
|
|
* a size of 0 - and if we are we'll simply return a null pointer. if not
|
|
* then reduce the size by 1 byte so that the subsequent calculations on
|
|
* the number of blocks to allocate are easier...
|
|
*/
|
|
|
|
if (0 == size) {
|
|
DBGLOG("malloc a block of 0 bytes -> do nothing\n");
|
|
|
|
return ptr;
|
|
}
|
|
|
|
/* Allocate the memory withing a protected critical section */
|
|
|
|
UMM_CRITICAL_ENTRY(id_malloc);
|
|
|
|
ptr = umm_malloc_core(size);
|
|
|
|
UMM_CRITICAL_EXIT(id_malloc);
|
|
|
|
return ptr;
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------ */
|
|
|
|
void *umm_realloc(void *ptr, size_t size) {
|
|
UMM_CRITICAL_DECL(id_realloc);
|
|
|
|
uint32_t blocks;
|
|
uint32_t blockSize;
|
|
uint32_t prevBlockSize = 0;
|
|
uint32_t nextBlockSize = 0;
|
|
|
|
uint32_t c;
|
|
|
|
size_t curSize;
|
|
|
|
/*
|
|
* This code looks after the case of a NULL value for ptr. The ANSI C
|
|
* standard says that if ptr is NULL and size is non-zero, then we've
|
|
* got to work the same a malloc(). If size is also 0, then our version
|
|
* of malloc() returns a NULL pointer, which is OK as far as the ANSI C
|
|
* standard is concerned.
|
|
*/
|
|
|
|
if (((void *)NULL == ptr)) {
|
|
DBGLOG("realloc the NULL pointer - call malloc()\n");
|
|
|
|
return umm_malloc(size);
|
|
}
|
|
|
|
/*
|
|
* Now we're sure that we have a non_NULL ptr, but we're not sure what
|
|
* we should do with it. If the size is 0, then the ANSI C standard says that
|
|
* we should operate the same as free.
|
|
*/
|
|
|
|
if (0 == size) {
|
|
DBGLOG("realloc to 0 size, just free the block\n");
|
|
|
|
umm_free(ptr);
|
|
|
|
return (void *)NULL;
|
|
}
|
|
|
|
/*
|
|
* Otherwise we need to actually do a reallocation. A naiive approach
|
|
* would be to malloc() a new block of the correct size, copy the old data
|
|
* to the new block, and then free the old block.
|
|
*
|
|
* While this will work, we end up doing a lot of possibly unnecessary
|
|
* copying. So first, let's figure out how many blocks we'll need.
|
|
*/
|
|
|
|
blocks = umm_blocks(size);
|
|
|
|
/* Figure out which block we're in. Note the use of truncated division... */
|
|
|
|
c = (((uint8_t *)ptr) - (uint8_t *)(&(UMM_HEAP[0]))) / UMM_BLOCKSIZE;
|
|
|
|
/* Figure out how big this block is ... the free bit is not set :-) */
|
|
|
|
blockSize = (UMM_NBLOCK(c) - c);
|
|
|
|
/* Figure out how many bytes are in this block */
|
|
|
|
curSize = (blockSize * UMM_BLOCKSIZE) - (sizeof(((umm_block *)0)->header));
|
|
|
|
/* Protect the critical section... */
|
|
UMM_CRITICAL_ENTRY(id_realloc);
|
|
|
|
/* Now figure out if the previous and/or next blocks are free as well as
|
|
* their sizes - this will help us to minimize special code later when we
|
|
* decide if it's possible to use the adjacent blocks.
|
|
*
|
|
* We set prevBlockSize and nextBlockSize to non-zero values ONLY if they
|
|
* are free!
|
|
*/
|
|
|
|
if ((UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_FREELIST_MASK)) {
|
|
nextBlockSize = (UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_BLOCKNO_MASK) - UMM_NBLOCK(c);
|
|
}
|
|
|
|
if ((UMM_NBLOCK(UMM_PBLOCK(c)) & UMM_FREELIST_MASK)) {
|
|
prevBlockSize = (c - UMM_PBLOCK(c));
|
|
}
|
|
|
|
DBGLOG("realloc blocks %i blockSize %i nextBlockSize %i prevBlockSize %i\n", blocks, blockSize, nextBlockSize, prevBlockSize);
|
|
|
|
/*
|
|
* Ok, now that we're here we know how many blocks we want and the current
|
|
* blockSize. The prevBlockSize and nextBlockSize are set and we can figure
|
|
* out the best strategy for the new allocation as follows:
|
|
*
|
|
* 1. If the new block is the same size or smaller than the current block do
|
|
* nothing.
|
|
* 2. If the next block is free and adding it to the current block gives us
|
|
* EXACTLY enough memory, assimilate the next block. This avoids unwanted
|
|
* fragmentation of free memory.
|
|
*
|
|
* The following cases may be better handled with memory copies to reduce
|
|
* fragmentation
|
|
*
|
|
* 3. If the previous block is NOT free and the next block is free and
|
|
* adding it to the current block gives us enough memory, assimilate
|
|
* the next block. This may introduce a bit of fragmentation.
|
|
* 4. If the prev block is free and adding it to the current block gives us
|
|
* enough memory, remove the previous block from the free list, assimilate
|
|
* it, copy to the new block.
|
|
* 5. If the prev and next blocks are free and adding them to the current
|
|
* block gives us enough memory, assimilate the next block, remove the
|
|
* previous block from the free list, assimilate it, copy to the new block.
|
|
* 6. Otherwise try to allocate an entirely new block of memory. If the
|
|
* allocation works free the old block and return the new pointer. If
|
|
* the allocation fails, return NULL and leave the old block intact.
|
|
*
|
|
* TODO: Add some conditional code to optimise for less fragmentation
|
|
* by simply allocating new memory if we need to copy anyways.
|
|
*
|
|
* All that's left to do is decide if the fit was exact or not. If the fit
|
|
* was not exact, then split the memory block so that we use only the requested
|
|
* number of blocks and add what's left to the free list.
|
|
*/
|
|
|
|
// Case 1 - block is same size or smaller
|
|
if (blockSize >= blocks) {
|
|
DBGLOG("realloc the same or smaller size block - %i, do nothing\n", blocks);
|
|
/* This space intentionally left blank */
|
|
|
|
// Case 2 - block + next block fits EXACTLY
|
|
} else if ((blockSize + nextBlockSize) == blocks) {
|
|
DBGLOG("exact realloc using next block - %i\n", blocks);
|
|
umm_assimilate_up(c);
|
|
blockSize += nextBlockSize;
|
|
|
|
// Case 3 - prev block NOT free and block + next block fits
|
|
} else if ((0 == prevBlockSize) && (blockSize + nextBlockSize) >= blocks) {
|
|
DBGLOG("realloc using next block - %i\n", blocks);
|
|
umm_assimilate_up(c);
|
|
blockSize += nextBlockSize;
|
|
|
|
// Case 4 - prev block + block fits
|
|
} else if ((prevBlockSize + blockSize) >= blocks) {
|
|
DBGLOG("realloc using prev block - %i\n", blocks);
|
|
umm_disconnect_from_free_list(UMM_PBLOCK(c));
|
|
c = umm_assimilate_down(c, 0);
|
|
memmove((void *)&UMM_DATA(c), ptr, curSize);
|
|
ptr = (void *)&UMM_DATA(c);
|
|
blockSize += prevBlockSize;
|
|
|
|
// Case 5 - prev block + block + next block fits
|
|
} else if ((prevBlockSize + blockSize + nextBlockSize) >= blocks) {
|
|
DBGLOG("realloc using prev and next block - %i\n", blocks);
|
|
umm_assimilate_up(c);
|
|
umm_disconnect_from_free_list(UMM_PBLOCK(c));
|
|
c = umm_assimilate_down(c, 0);
|
|
memmove((void *)&UMM_DATA(c), ptr, curSize);
|
|
ptr = (void *)&UMM_DATA(c);
|
|
blockSize += (prevBlockSize + nextBlockSize);
|
|
|
|
// Case 6 - default is we need to realloc a new block
|
|
} else {
|
|
DBGLOG("realloc a completely new block %i\n", blocks);
|
|
void *oldptr = ptr;
|
|
if ((ptr = umm_malloc_core(size))) {
|
|
DBGLOG("realloc %i to a bigger block %i, copy, and free the old\n", blockSize, blocks);
|
|
memcpy(ptr, oldptr, curSize);
|
|
umm_free_core(oldptr);
|
|
} else {
|
|
DBGLOG("realloc %i to a bigger block %i failed - return NULL and leave the old block!\n", blockSize, blocks);
|
|
/* This space intentionally left blnk */
|
|
}
|
|
blockSize = blocks;
|
|
}
|
|
|
|
/* Now all we need to do is figure out if the block fit exactly or if we
|
|
* need to split and free ...
|
|
*/
|
|
|
|
if (blockSize > blocks) {
|
|
DBGLOG("split and free %i blocks from %i\n", blocks, blockSize);
|
|
umm_split_block(c, blocks, 0);
|
|
umm_free_core((void *)&UMM_DATA(c + blocks));
|
|
}
|
|
|
|
/* Release the critical section... */
|
|
UMM_CRITICAL_EXIT(id_realloc);
|
|
|
|
return ptr;
|
|
}
|
|
|
|
|
|
// The openssl library expects a version of malloc that takes
|
|
// extra parameters 'file' and 'line'. We provide these for openssl.
|
|
// The extra parameters are ignored.
|
|
|
|
void *umm_malloc_ssl(size_t size, const char *file, int line) {
|
|
return umm_malloc(size);
|
|
}
|
|
|
|
void *umm_realloc_ssl(void *ptr, size_t size, const char *file, int line) {
|
|
return umm_realloc(ptr, size);
|
|
}
|
|
|
|
void umm_free_ssl(void *ptr, const char *file, int line) {
|
|
umm_free(ptr);
|
|
}
|