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pinebuds/services/interconnection/umm_malloc/umm_malloc.c

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C
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#include "umm_malloc.h"
#include "cmsis_os.h"
#include "dbglog.h"
#include "stdint.h"
#include <stdio.h>
#include <string.h>
/* Use the default DBGLOG_LEVEL and DBGLOG_FUNCTION */
unsigned char umm_heap_array[UMM_MALLOC_CFG_HEAP_SIZE];
/* ------------------------------------------------------------------------- */
UMM_H_ATTPACKPRE typedef struct umm_ptr_t {
unsigned short int next;
unsigned short int prev;
} UMM_H_ATTPACKSUF umm_ptr;
UMM_H_ATTPACKPRE typedef struct umm_block_t {
union {
umm_ptr used;
} header;
union {
umm_ptr free;
unsigned char data[4];
} body;
} UMM_H_ATTPACKSUF umm_block;
#define UMM_FREELIST_MASK (0x8000)
#define UMM_BLOCKNO_MASK (0x7FFF)
/* ------------------------------------------------------------------------- */
umm_block *umm_heap = NULL;
unsigned short int umm_numblocks = 0;
#define UMM_NUMBLOCKS (umm_numblocks)
/* ------------------------------------------------------------------------ */
#define UMM_BLOCK(b) (umm_heap[b])
#define UMM_NBLOCK(b) (UMM_BLOCK(b).header.used.next)
#define UMM_PBLOCK(b) (UMM_BLOCK(b).header.used.prev)
#define UMM_NFREE(b) (UMM_BLOCK(b).body.free.next)
#define UMM_PFREE(b) (UMM_BLOCK(b).body.free.prev)
#define UMM_DATA(b) (UMM_BLOCK(b).body.data)
static osMutexId umm_clock_mutex_id = NULL;
osMutexDef(umm_clock_mutex);
/* ------------------------------------------------------------------------ */
void LOCK_UMM_CLOCK(void) {
if (osMutexWait(umm_clock_mutex_id, osWaitForever) != osOK)
DBGLOG_INFO(1, "%s Error", __func__);
}
void UNLOCK_UMM_CLOCK(void) {
if (osMutexRelease(umm_clock_mutex_id) != osOK)
DBGLOG_INFO(1, "%s Error", __func__);
}
/* ------------------------------------------------------------------------ */
static void trace_umm_blocks_info(void) {
unsigned short int blockSize = 0;
unsigned short int cf = 0;
cf = UMM_NFREE(0);
blockSize = blockSize;
DBGLOG_INFO(1, "fisrt free block %d", cf);
while (cf) {
blockSize = (UMM_NBLOCK(cf) & UMM_BLOCKNO_MASK) - cf;
DBGLOG_INFO(2, "Looking at block %6i size %6i\n", cf, blockSize);
cf = UMM_NFREE(cf);
}
}
/* ------------------------------------------------------------------------ */
static unsigned short int umm_blocks(size_t size) {
/*
* The calculation of the block size is not too difficult, but there are
* a few little things that we need to be mindful of.
*
* When a block removed from the free list, the space used by the free
* pointers is available for data. That's what the first calculation
* of size is doing.
*/
if (size <= (sizeof(((umm_block *)0)->body)))
return (1);
/*
* If it's for more than that, then we need to figure out the number of
* additional whole blocks the size of an umm_block are required.
*/
size -= (1 + (sizeof(((umm_block *)0)->body)));
return (2 + size / (sizeof(umm_block)));
}
/* ------------------------------------------------------------------------ */
/*
* Split the block `c` into two blocks: `c` and `c + blocks`.
*
* - `new_freemask` should be `0` if `c + blocks` used, or `UMM_FREELIST_MASK`
* otherwise.
*
* Note that free pointers are NOT modified by this function.
*/
static void umm_split_block(unsigned short int c, unsigned short int blocks,
unsigned short int new_freemask) {
UMM_NBLOCK(c + blocks) = (UMM_NBLOCK(c) & UMM_BLOCKNO_MASK) | new_freemask;
UMM_PBLOCK(c + blocks) = c;
UMM_PBLOCK(UMM_NBLOCK(c) & UMM_BLOCKNO_MASK) = (c + blocks);
UMM_NBLOCK(c) = (c + blocks);
}
/* ------------------------------------------------------------------------ */
static void umm_disconnect_from_free_list(unsigned short int c) {
/* Disconnect this block from the FREE list */
UMM_NFREE(UMM_PFREE(c)) = UMM_NFREE(c);
UMM_PFREE(UMM_NFREE(c)) = UMM_PFREE(c);
/* And clear the free block indicator */
UMM_NBLOCK(c) &= (~UMM_FREELIST_MASK);
}
/* ------------------------------------------------------------------------
* The umm_assimilate_up() function assumes that UMM_NBLOCK(c) does NOT
* have the UMM_FREELIST_MASK bit set!
*/
static void umm_assimilate_up(unsigned short int c) {
if (UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_FREELIST_MASK) {
/*
* The next block is a free block, so assimilate up and remove it from
* the free list
*/
DBGLOG_DEBUG(2, "%d Assimilate up to next block %d, which is FREE\n", c,
UMM_NBLOCK(c));
/* Disconnect the next block from the FREE list */
umm_disconnect_from_free_list(UMM_NBLOCK(c));
/* Assimilate the next block with this one */
UMM_PBLOCK(UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_BLOCKNO_MASK) = c;
UMM_NBLOCK(c) = UMM_NBLOCK(UMM_NBLOCK(c)) & UMM_BLOCKNO_MASK;
}
}
/* ------------------------------------------------------------------------
* The umm_assimilate_down() function assumes that UMM_NBLOCK(c) does NOT
* have the UMM_FREELIST_MASK bit set!
*/
static unsigned short int umm_assimilate_down(unsigned short int c,
unsigned short int freemask) {
UMM_NBLOCK(UMM_PBLOCK(c)) = UMM_NBLOCK(c) | freemask;
UMM_PBLOCK(UMM_NBLOCK(c)) = UMM_PBLOCK(c);
return (UMM_PBLOCK(c));
}
/* ------------------------------------------------------------------------- */
void umm_init(void) {
/* init heap pointer and size, and memset it to 0 */
umm_heap = (umm_block *)UMM_MALLOC_CFG_HEAP_ADDR;
umm_numblocks = (UMM_MALLOC_CFG_HEAP_SIZE / sizeof(umm_block));
DBGLOG_DEBUG(3, "%s umm_heap %p blocks number %d", __func__, umm_heap,
umm_numblocks);
if (umm_clock_mutex_id == NULL) {
umm_clock_mutex_id = osMutexCreate((osMutex(umm_clock_mutex)));
}
memset(umm_heap, 0x00, UMM_MALLOC_CFG_HEAP_SIZE);
/* setup initial blank heap structure */
{
/* index of the 0th `umm_block` */
const unsigned short int block_0th = 0;
/* index of the 1st `umm_block` */
const unsigned short int block_1th = 1;
/* index of the latest `umm_block` */
const unsigned short int block_last = UMM_NUMBLOCKS - 1;
/* setup the 0th `umm_block`, which just points to the 1st */
UMM_NBLOCK(block_0th) = block_1th;
UMM_NFREE(block_0th) = block_1th;
UMM_PFREE(block_0th) = block_1th;
/*
* Now, we need to set the whole heap space as a huge free block. We should
* not touch the 0th `umm_block`, since it's special: the 0th `umm_block`
* is the head of the free block list. It's a part of the heap invariant.
*
* See the detailed explanation at the beginning of the file.
*/
/*
* 1th `umm_block` has pointers:
*
* - next `umm_block`: the latest one
* - prev `umm_block`: the 0th
*
* Plus, it's a free `umm_block`, so we need to apply `UMM_FREELIST_MASK`
*
* And it's the last free block, so the next free block is 0.
*/
UMM_NBLOCK(block_1th) = block_last | UMM_FREELIST_MASK;
UMM_NFREE(block_1th) = 0;
UMM_PBLOCK(block_1th) = block_0th;
UMM_PFREE(block_1th) = block_0th;
/*
* latest `umm_block` has pointers:
*
* - next `umm_block`: 0 (meaning, there are no more `umm_blocks`)
* - prev `umm_block`: the 1st
*
* It's not a free block, so we don't touch NFREE / PFREE at all.
*/
UMM_NBLOCK(block_last) = 0;
UMM_PBLOCK(block_last) = block_1th;
}
}
/* ------------------------------------------------------------------------ */
void umm_free(void *ptr) {
unsigned short int c;
/* If we're being asked to free a NULL pointer, well that's just silly! */
if ((void *)0 == ptr) {
DBGLOG_DEBUG(0, "free a null pointer -> do nothing\n");
return;
}
/*
* 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!
*
* NOTE: See the new umm_info() function that you can use to see if a ptr is
* on the free list!
*/
/* Protect the critical section... */
UMM_CRITICAL_ENTRY();
/* Figure out which block we're in. Note the use of truncated division... */
c = (((char *)ptr) - (char *)(&(umm_heap[0]))) / sizeof(umm_block);
DBGLOG_DEBUG(2, "Freeing block %6i %p\n", c, ptr);
/* 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_DEBUG(1, "Assimilate down to next block %d, which is FREE\n",
UMM_PBLOCK(c));
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_DEBUG(0, "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;
}
/* Release the critical section... */
UMM_CRITICAL_EXIT();
}
/* ------------------------------------------------------------------------ */
void *umm_malloc(size_t size) {
unsigned short int blocks;
unsigned short int blockSize = 0;
unsigned short int bestSize;
unsigned short int bestBlock;
unsigned short int cf;
if (umm_heap == NULL) {
umm_init();
}
/*
* 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_DEBUG(0, "malloc a block of 0 bytes -> do nothing\n");
return ((void *)NULL);
}
/* Protect the critical section... */
UMM_CRITICAL_ENTRY();
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 = 0x7FFF;
while (cf) {
blockSize = (UMM_NBLOCK(cf) & UMM_BLOCKNO_MASK) - cf;
DBGLOG_DEBUG(2, "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 (0x7FFF != 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_DEBUG(2, "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_DEBUG(2, "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_DEBUG(1, "Can't allocate %5i blocks\n", blocks);
trace_umm_blocks_info();
/* Release the critical section... */
UMM_CRITICAL_EXIT();
return ((void *)NULL);
}
/* Release the critical section... */
UMM_CRITICAL_EXIT();
return ((void *)&UMM_DATA(cf));
}
/* ------------------------------------------------------------------------ */
void *umm_realloc(void *ptr, size_t size) {
unsigned short int blocks;
unsigned short int blockSize;
unsigned short int prevBlockSize = 0;
unsigned short int nextBlockSize = 0;
unsigned short int c;
size_t curSize;
if (umm_heap == NULL) {
umm_init();
}
/*
* 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_DEBUG(0, "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_DEBUG(0, "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 = (((char *)ptr) - (char *)(&(umm_heap[0]))) / sizeof(umm_block);
/* 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 * sizeof(umm_block)) - (sizeof(((umm_block *)0)->header));
/* Protect the critical section... */
UMM_CRITICAL_ENTRY();
/* 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_DEBUG(
4, "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
* enough memory, assimilate the next block.
* 3. 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.
* 4. 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.
* 5. 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.
*
* 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.
*/
if (blockSize >= blocks) {
DBGLOG_DEBUG(1, "realloc the same or smaller size block - %i, do nothing\n",
blocks);
/* This space intentionally left blank */
} else if ((blockSize + nextBlockSize) >= blocks) {
DBGLOG_DEBUG(1, "realloc using next block - %i\n", blocks);
umm_assimilate_up(c);
blockSize += nextBlockSize;
} else if ((prevBlockSize + blockSize) >= blocks) {
DBGLOG_DEBUG(1, "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;
} else if ((prevBlockSize + blockSize + nextBlockSize) >= blocks) {
DBGLOG_DEBUG(1, "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);
} else {
DBGLOG_DEBUG(1, "realloc a completely new block %i\n", blocks);
void *oldptr = ptr;
if ((ptr = umm_malloc(size))) {
DBGLOG_DEBUG(2,
"realloc %i to a bigger block %i, copy, and free the old\n",
blockSize, blocks);
memcpy(ptr, oldptr, curSize);
umm_free(oldptr);
} else {
DBGLOG_DEBUG(2,
"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_DEBUG(2, "split and free %i blocks from %i\n", blocks, blockSize);
umm_split_block(c, blocks, 0);
umm_free((void *)&UMM_DATA(c + blocks));
}
/* Release the critical section... */
UMM_CRITICAL_EXIT();
return (ptr);
}
/* ------------------------------------------------------------------------ */
void *umm_calloc(size_t num, size_t item_size) {
void *ret;
ret = umm_malloc((size_t)(item_size * num));
if (ret)
memset(ret, 0x00, (size_t)(item_size * num));
return ret;
}
/* ------------------------------------------------------------------------ */
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