summaryrefslogtreecommitdiffstats
path: root/lib/libstand/zalloc.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/libstand/zalloc.c')
-rw-r--r--lib/libstand/zalloc.c302
1 files changed, 302 insertions, 0 deletions
diff --git a/lib/libstand/zalloc.c b/lib/libstand/zalloc.c
new file mode 100644
index 0000000..16a4163
--- /dev/null
+++ b/lib/libstand/zalloc.c
@@ -0,0 +1,302 @@
+/*
+ * This module derived from code donated to the FreeBSD Project by
+ * Matthew Dillon <dillon@backplane.com>
+ *
+ * Copyright (c) 1998 The FreeBSD Project
+ * All rights reserved.
+ *
+ * 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 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+/*
+ * LIB/MEMORY/ZALLOC.C - self contained low-overhead memory pool/allocation
+ * subsystem
+ *
+ * This subsystem implements memory pools and memory allocation
+ * routines.
+ *
+ * Pools are managed via a linked list of 'free' areas. Allocating
+ * memory creates holes in the freelist, freeing memory fills them.
+ * Since the freelist consists only of free memory areas, it is possible
+ * to allocate the entire pool without incuring any structural overhead.
+ *
+ * The system works best when allocating similarly-sized chunks of
+ * memory. Care must be taken to avoid fragmentation when
+ * allocating/deallocating dissimilar chunks.
+ *
+ * When a memory pool is first allocated, the entire pool is marked as
+ * allocated. This is done mainly because we do not want to modify any
+ * portion of a pool's data area until we are given permission. The
+ * caller must explicitly deallocate portions of the pool to make them
+ * available.
+ *
+ * z[n]xalloc() works like z[n]alloc() but the allocation is made from
+ * within the specified address range. If the segment could not be
+ * allocated, NULL is returned. WARNING! The address range will be
+ * aligned to an 8 or 16 byte boundry depending on the cpu so if you
+ * give an unaligned address range, unexpected results may occur.
+ *
+ * If a standard allocation fails, the reclaim function will be called
+ * to recover some space. This usually causes other portions of the
+ * same pool to be released. Memory allocations at this low level
+ * should not block but you can do that too in your reclaim function
+ * if you want. Reclaim does not function when z[n]xalloc() is used,
+ * only for z[n]alloc().
+ *
+ * Allocation and frees of 0 bytes are valid operations.
+ */
+
+#include "zalloc_defs.h"
+
+/*
+ * znalloc() - allocate memory (without zeroing) from pool. Call reclaim
+ * and retry if appropriate, return NULL if unable to allocate
+ * memory.
+ */
+
+void *
+znalloc(MemPool *mp, iaddr_t bytes)
+{
+ /*
+ * align according to pool object size (can be 0). This is
+ * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
+ *
+ */
+ bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
+
+ if (bytes == 0)
+ return((void *)-1);
+
+ /*
+ * locate freelist entry big enough to hold the object. If all objects
+ * are the same size, this is a constant-time function.
+ */
+
+ if (bytes <= mp->mp_Size - mp->mp_Used) {
+ MemNode **pmn;
+ MemNode *mn;
+
+ for (pmn = &mp->mp_First; (mn=*pmn) != NULL; pmn = &mn->mr_Next) {
+ if (bytes > mn->mr_Bytes)
+ continue;
+
+ /*
+ * Cut a chunk of memory out of the beginning of this
+ * block and fixup the link appropriately.
+ */
+
+ {
+ char *ptr = (char *)mn;
+
+ if (mn->mr_Bytes == bytes) {
+ *pmn = mn->mr_Next;
+ } else {
+ mn = (MemNode *)((char *)mn + bytes);
+ mn->mr_Next = ((MemNode *)ptr)->mr_Next;
+ mn->mr_Bytes = ((MemNode *)ptr)->mr_Bytes - bytes;
+ *pmn = mn;
+ }
+ mp->mp_Used += bytes;
+ return(ptr);
+ }
+ }
+ }
+
+ /*
+ * Memory pool is full, return NULL.
+ */
+
+ return(NULL);
+}
+
+/*
+ * zfree() - free previously allocated memory
+ */
+
+void
+zfree(MemPool *mp, void *ptr, iaddr_t bytes)
+{
+ /*
+ * align according to pool object size (can be 0). This is
+ * inclusive of the MEMNODE_SIZE_MASK minimum alignment.
+ */
+ bytes = (bytes + MEMNODE_SIZE_MASK) & ~MEMNODE_SIZE_MASK;
+
+ if (bytes == 0)
+ return;
+
+ /*
+ * panic if illegal pointer
+ */
+
+ if ((char *)ptr < (char *)mp->mp_Base ||
+ (char *)ptr + bytes > (char *)mp->mp_End ||
+ ((iaddr_t)ptr & MEMNODE_SIZE_MASK) != 0)
+ panic("zfree(%p,%d): wild pointer", ptr, bytes);
+
+ /*
+ * free the segment
+ */
+
+ {
+ MemNode **pmn;
+ MemNode *mn;
+
+ mp->mp_Used -= bytes;
+
+ for (pmn = &mp->mp_First; (mn = *pmn) != NULL; pmn = &mn->mr_Next) {
+ /*
+ * If area between last node and current node
+ * - check range
+ * - check merge with next area
+ * - check merge with previous area
+ */
+ if ((char *)ptr <= (char *)mn) {
+ /*
+ * range check
+ */
+ if ((char *)ptr + bytes > (char *)mn)
+ panic("zfree(%p,%d): corrupt memlist1",ptr, bytes);
+
+ /*
+ * merge against next area or create independant area
+ */
+
+ if ((char *)ptr + bytes == (char *)mn) {
+ ((MemNode *)ptr)->mr_Next = mn->mr_Next;
+ ((MemNode *)ptr)->mr_Bytes= bytes + mn->mr_Bytes;
+ } else {
+ ((MemNode *)ptr)->mr_Next = mn;
+ ((MemNode *)ptr)->mr_Bytes= bytes;
+ }
+ *pmn = mn = (MemNode *)ptr;
+
+ /*
+ * merge against previous area (if there is a previous
+ * area).
+ */
+
+ if (pmn != &mp->mp_First) {
+ if ((char*)pmn + ((MemNode*)pmn)->mr_Bytes == (char*)ptr) {
+ ((MemNode *)pmn)->mr_Next = mn->mr_Next;
+ ((MemNode *)pmn)->mr_Bytes += mn->mr_Bytes;
+ mn = (MemNode *)pmn;
+ }
+ }
+ return;
+ /* NOT REACHED */
+ }
+ if ((char *)ptr < (char *)mn + mn->mr_Bytes)
+ panic("zfree(%p,%d): corrupt memlist2", ptr, bytes);
+ }
+ /*
+ * We are beyond the last MemNode, append new MemNode. Merge against
+ * previous area if possible.
+ */
+ if (pmn == &mp->mp_First ||
+ (char *)pmn + ((MemNode *)pmn)->mr_Bytes != (char *)ptr
+ ) {
+ ((MemNode *)ptr)->mr_Next = NULL;
+ ((MemNode *)ptr)->mr_Bytes = bytes;
+ *pmn = (MemNode *)ptr;
+ mn = (MemNode *)ptr;
+ } else {
+ ((MemNode *)pmn)->mr_Bytes += bytes;
+ mn = (MemNode *)pmn;
+ }
+ }
+}
+
+/*
+ * zextendPool() - extend memory pool to cover additional space.
+ *
+ * Note: the added memory starts out as allocated, you
+ * must free it to make it available to the memory subsystem.
+ *
+ * Note: mp_Size may not reflect (mp_End - mp_Base) range
+ * due to other parts of the system doing their own sbrk()
+ * calls.
+ */
+
+void
+zextendPool(MemPool *mp, void *base, iaddr_t bytes)
+{
+ if (mp->mp_Size == 0) {
+ mp->mp_Base = base;
+ mp->mp_Used = bytes;
+ mp->mp_End = (char *)base + bytes;
+ } else {
+ void *pend = (char *)mp->mp_Base + mp->mp_Size;
+
+ if (base < mp->mp_Base) {
+ /* mp->mp_Size += (char *)mp->mp_Base - (char *)base; */
+ mp->mp_Used += (char *)mp->mp_Base - (char *)base;
+ mp->mp_Base = base;
+ }
+ base = (char *)base + bytes;
+ if (base > pend) {
+ /* mp->mp_Size += (char *)base - (char *)pend; */
+ mp->mp_Used += (char *)base - (char *)pend;
+ mp->mp_End = (char *)base;
+ }
+ }
+ mp->mp_Size += bytes;
+}
+
+#ifdef ZALLOCDEBUG
+
+void
+zallocstats(MemPool *mp)
+{
+ int abytes = 0;
+ int hbytes = 0;
+ int fcount = 0;
+ MemNode *mn;
+
+ printf("%d bytes reserved", (int) mp->mp_Size);
+
+ mn = mp->mp_First;
+
+ if ((void *)mn != (void *)mp->mp_Base) {
+ abytes += (char *)mn - (char *)mp->mp_Base;
+ }
+
+ while (mn) {
+ if ((char *)mn + mn->mr_Bytes != mp->mp_End) {
+ hbytes += mn->mr_Bytes;
+ ++fcount;
+ }
+ if (mn->mr_Next)
+ abytes += (char *)mn->mr_Next - ((char *)mn + mn->mr_Bytes);
+ mn = mn->mr_Next;
+ }
+ printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",
+ abytes,
+ fcount,
+ hbytes
+ );
+}
+
+#endif
+
OpenPOWER on IntegriCloud