2.11BSD/src/bin/tcsh/tc.alloc.c
/*
* tc.alloc.c (Caltech) 2/21/82
* Chris Kingsley, kingsley@cit-20.
*
* This is a very fast storage allocator. It allocates blocks of a small
* number of different sizes, and keeps free lists of each size. Blocks that
* don't exactly fit are passed up to the next larger size. In this
* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
* This is designed for use in a program that uses vast quantities of memory,
* but bombs when it runs out.
*/
/*-
* Copyright (c) 1980, 1991 The Regents of the University of California.
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
*/
#include "config.h"
#if !defined(lint) && !defined(pdp11)
static char *rcsid()
{ return "$Id: tc.alloc.c,v 3.0.1 1996/04/04 21:49:28 sms Exp $"; }
#endif
#include "sh.h"
char *memtop = NULL; /* PWP: top of current memory */
char *membot = NULL; /* PWP: bottom of allocatable memory */
#ifndef SYSMALLOC
#define RCHECK
#define DEBUG
#ifndef NULL
#define NULL 0
#endif
typedef unsigned char U_char; /* we don't really have signed chars */
#ifdef pdp11
typedef u_long U_int;
#else
typedef unsigned int U_int;
#endif
typedef unsigned short U_short;
/*
* The overhead on a block is at least 4 bytes. When free, this space
* contains a pointer to the next free block, and the bottom two bits must
* be zero. When in use, the first byte is set to MAGIC, and the second
* byte is the size index. The remaining bytes are for alignment.
* If range checking is enabled and the size of the block fits
* in two bytes, then the top two bytes hold the size of the requested block
* plus the range checking words, and the header word MINUS ONE.
*/
#define MEMALIGN(a) (((a) + ROUNDUP) & ~ROUNDUP)
union overhead {
union overhead *ov_next; /* when free */
struct {
U_char ovu_magic; /* magic number */
U_char ovu_index; /* bucket # */
#ifdef RCHECK
U_short ovu_size; /* actual block size */
U_int ovu_rmagic; /* range magic number */
#endif
} ovu;
#define ov_magic ovu.ovu_magic
#define ov_index ovu.ovu_index
#define ov_size ovu.ovu_size
#define ov_rmagic ovu.ovu_rmagic
};
#define MAGIC 0xfd /* magic # on accounting info */
#define RMAGIC 0x55555555 /* magic # on range info */
#ifdef RCHECK
#define RSLOP sizeof (U_int)
#else
#define RSLOP 0
#endif
#ifdef SUNOS4
/*
* SunOS localtime() overwrites the 9th byte on an 8 byte malloc()....
* So we align to 16 bytes...
*/
#define ROUNDUP 15
#else
#define ROUNDUP 7
#endif
/*
* nextf[i] is the pointer to the next free block of size 2^(i+3). The
* smallest allocatable block is 8 bytes. The overhead information
* precedes the data area returned to the user.
*/
#define NBUCKETS 30
static union overhead *nextf[NBUCKETS];
#ifdef notdef
extern char *sbrk();
#endif
/*
* nmalloc[i] is the difference between the number of mallocs and frees
* for a given block size.
*/
static U_int nmalloc[NBUCKETS];
static int findbucket __P((union overhead *, int));
static void morecore __P((int));
#ifdef DEBUG
#define CHECK(a, str, p) \
if (a) { \
xprintf(str, p); \
xprintf("memtop = %lx membot = %lx.\n", memtop, membot); \
abort(); \
} \
else
#else
#define CHECK(a, str, p) \
if (a) { \
xprintf(str, p); \
xprintf("memtop = %lx membot = %lx.\n", memtop, membot); \
return; \
} \
else
#endif
memalign_t
malloc(nbytes)
register size_t nbytes;
{
#ifndef lint
register union overhead *p;
register int bucket = 0;
register unsigned shiftr;
/*
* Convert amount of memory requested into closest block size stored in
* hash buckets which satisfies request. Account for space used per block
* for accounting.
*/
nbytes = MEMALIGN(MEMALIGN(sizeof(union overhead)) + nbytes + RSLOP);
shiftr = (nbytes - 1) >> 2;
/* apart from this loop, this is O(1) */
while (shiftr >>= 1)
bucket++;
/*
* If nothing in hash bucket right now, request more memory from the
* system.
*/
if (nextf[bucket] == NULL)
morecore(bucket);
if ((p = (union overhead *) nextf[bucket]) == NULL) {
child++;
#ifndef DEBUG
stderror(ERR_NOMEM);
#else
showall();
xprintf("nbytes=%d: Out of memory\n", nbytes);
abort();
#endif
/* fool lint */
return ((memalign_t) 0);
}
/* remove from linked list */
nextf[bucket] = nextf[bucket]->ov_next;
p->ov_magic = MAGIC;
p->ov_index = bucket;
nmalloc[bucket]++;
#ifdef RCHECK
/*
* Record allocated size of block and bound space with magic numbers.
*/
if (nbytes <= 0x10000)
p->ov_size = nbytes - 1;
p->ov_rmagic = RMAGIC;
*((U_int *) (((caddr_t) p) + nbytes - RSLOP)) = RMAGIC;
#endif
return ((memalign_t) (((caddr_t) p) + MEMALIGN(sizeof(union overhead))));
#else
if (nbytes)
return ((memalign_t) 0);
else
return ((memalign_t) 0);
#endif /* !lint */
}
#ifndef lint
/*
* Allocate more memory to the indicated bucket.
*/
static void
morecore(bucket)
register bucket;
{
register union overhead *op;
register int rnu; /* 2^rnu bytes will be requested */
register int nblks; /* become nblks blocks of the desired size */
register int siz;
if (nextf[bucket])
return;
/*
* Insure memory is allocated on a page boundary. Should make getpageize
* call?
*/
op = (union overhead *) sbrk(0);
memtop = (char *) op;
if (membot == NULL)
membot = memtop;
if ((int) op & 0x3ff) {
memtop = (char *) sbrk(1024 - ((int) op & 0x3ff));
memtop += 1024 - ((int) op & 0x3ff);
}
/* take 2k unless the block is bigger than that */
rnu = (bucket <= 8) ? 11 : bucket + 3;
nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
if (rnu < bucket)
rnu = bucket;
memtop = (char *) sbrk(1 << rnu); /* PWP */
op = (union overhead *) memtop;
memtop += 1 << rnu;
/* no more room! */
if ((int) op == -1)
return;
/*
* Round up to minimum allocation size boundary and deduct from block count
* to reflect.
*/
if (((U_int) op) & ROUNDUP) {
op = (union overhead *) (((U_int) op + (ROUNDUP + 1)) & ~ROUNDUP);
nblks--;
}
/*
* Add new memory allocated to that on free list for this hash bucket.
*/
nextf[bucket] = op;
siz = 1 << (bucket + 3);
while (--nblks > 0) {
op->ov_next = (union overhead *) (((caddr_t) op) + siz);
op = (union overhead *) (((caddr_t) op) + siz);
}
}
#endif
void
free(cp)
ptr_t cp;
{
#ifndef lint
register int size;
register union overhead *op;
if (cp == NULL)
return;
CHECK(!memtop || !membot, "free(%lx) called before any allocations.", cp);
CHECK(cp > (ptr_t) memtop, "free(%lx) above top of memory.", cp);
CHECK(cp < (ptr_t) membot, "free(%lx) above top of memory.", cp);
op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
CHECK(op->ov_magic != MAGIC, "free(%lx) bad block.", cp);
#ifdef RCHECK
if (op->ov_index <= 13)
CHECK(*(U_int *) ((caddr_t) op + op->ov_size + 1 - RSLOP) != RMAGIC,
"free(%lx) bad range check.", cp);
#endif
CHECK(op->ov_index >= NBUCKETS, "free(%lx) bad block index.", cp);
size = op->ov_index;
op->ov_next = nextf[size];
nextf[size] = op;
nmalloc[size]--;
#else
if (cp == NULL)
return;
#endif
}
memalign_t
calloc(i, j)
size_t i, j;
{
#ifndef lint
register char *cp, *scp;
i *= j;
scp = cp = (char *) xmalloc((size_t) i);
if (i != 0)
do
*cp++ = 0;
while (--i);
return (scp);
#else
if (i && j)
return ((memalign_t) 0);
else
return ((memalign_t) 0);
#endif
}
#ifndef lint
/* PWP: a bcopy that does overlapping extents correctly */
static void
mybcopy(from, to, len)
char *from, *to;
register unsigned len;
{
register char *sp, *dp;
if (from == to)
return;
if (from < to) {
/* len is unsigned, len > 0 is equivalent to len != 0 */
for (sp = &from[len - 1], dp = &to[len - 1]; len != 0; len--, sp--, dp--)
*dp = *sp;
}
else {
/* len is unsigned, len > 0 is equivalent to len != 0 */
for (sp = from, dp = to; len != 0; len--, sp++, dp++)
*dp = *sp;
}
}
#endif
/*
* When a program attempts "storage compaction" as mentioned in the
* old malloc man page, it realloc's an already freed block. Usually
* this is the last block it freed; occasionally it might be farther
* back. We have to search all the free lists for the block in order
* to determine its bucket: 1st we make one pass thru the lists
* checking only the first block in each; if that fails we search
* ``realloc_srchlen'' blocks in each list for a match (the variable
* is extern so the caller can modify it). If that fails we just copy
* however many bytes was given to realloc() and hope it's not huge.
*/
#ifndef lint
int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
#endif /* lint */
memalign_t
realloc(cp, nbytes)
ptr_t cp;
size_t nbytes;
{
#ifndef lint
register U_int onb;
union overhead *op;
char *res;
register int i;
int was_alloced = 0;
if (cp == NULL)
return (malloc(nbytes));
op = (union overhead *) (((caddr_t) cp) - MEMALIGN(sizeof(union overhead)));
if (op->ov_magic == MAGIC) {
was_alloced++;
i = op->ov_index;
}
else
/*
* Already free, doing "compaction".
*
* Search for the old block of memory on the free list. First, check the
* most common case (last element free'd), then (this failing) the last
* ``realloc_srchlen'' items free'd. If all lookups fail, then assume
* the size of the memory block being realloc'd is the smallest
* possible.
*/
if ((i = findbucket(op, 1)) < 0 &&
(i = findbucket(op, realloc_srchlen)) < 0)
i = 0;
onb = MEMALIGN(nbytes + MEMALIGN(sizeof(union overhead)) + RSLOP);
/* avoid the copy if same size block */
if (was_alloced && (onb < (1 << (i + 3))) && (onb >= (1 << (i + 2))))
return ((memalign_t) cp);
if ((res = malloc(nbytes)) == NULL)
return (NULL);
if (cp != res) /* common optimization */
mybcopy(cp, res, nbytes);
if (was_alloced)
free(cp);
return (res);
#else
if (cp && nbytes)
return ((memalign_t) 0);
else
return ((memalign_t) 0);
#endif /* !lint */
}
#ifndef lint
/*
* Search ``srchlen'' elements of each free list for a block whose
* header starts at ``freep''. If srchlen is -1 search the whole list.
* Return bucket number, or -1 if not found.
*/
static int
findbucket(freep, srchlen)
union overhead *freep;
int srchlen;
{
register union overhead *p;
register int i, j;
for (i = 0; i < NBUCKETS; i++) {
j = 0;
for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
if (p == freep)
return (i);
j++;
}
}
return (-1);
}
#endif
#else /* SYSMALLOC */
/**
** ``Protected versions'' of malloc, realloc, calloc, and free
**
** On many systems:
**
** 1. malloc(0) is bad
** 2. free(0) is bad
** 3. realloc(0, n) is bad
** 4. realloc(n, 0) is bad
**
** Also we call our error routine if we run out of memory.
**/
memalign_t
Malloc(n)
size_t n;
{
ptr_t ptr;
n = n ? n : 1;
if ((ptr = malloc(n)) == (ptr_t) 0) {
child++;
stderror(ERR_NOMEM);
}
return ((memalign_t) ptr);
}
memalign_t
Realloc(p, n)
ptr_t p;
register size_t n;
{
ptr_t ptr;
n = n ? n : 1;
if ((ptr = (p ? realloc(p, n) : malloc(n))) == (ptr_t) 0) {
child++;
stderror(ERR_NOMEM);
}
return ((memalign_t) ptr);
}
memalign_t
Calloc(s, n)
register size_t s, n;
{
register char *sptr;
ptr_t ptr;
n *= s;
n = n ? n : 1;
if ((ptr = malloc(n)) == (ptr_t) 0) {
child++;
stderror(ERR_NOMEM);
}
sptr = (char *) ptr;
if (n != 0)
do
*sptr++ = 0;
while (--n);
return ((memalign_t) ptr);
}
void
Free(p)
ptr_t p;
{
if (p) {
free(p);
/*
* jpn: free() doesn't NULL pointers on all systems
* but tcsh seems to expect it: see sh.c where comment that
* xfree doesn't care if called twice on same pointers,
* and fact that Free here tests pointer before freeing it.
*/
p = NULL;
}
}
#endif /* SYSMALLOC */
#ifndef pdp11
/*
* mstats - print out statistics about malloc
*
* Prints two lines of numbers, one showing the length of the free list
* for each size category, the second showing the number of mallocs -
* frees for each size category.
*/
void
showall()
{
#ifndef SYSMALLOC
register int i, j;
register union overhead *p;
int totfree = 0, totused = 0;
xprintf("tcsh current memory allocation:\nfree:\t");
for (i = 0; i < NBUCKETS; i++) {
for (j = 0, p = nextf[i]; p; p = p->ov_next, j++);
xprintf(" %4d", j);
totfree += j * (1 << (i + 3));
}
xprintf("\nused:\t");
for (i = 0; i < NBUCKETS; i++) {
xprintf(" %4d", nmalloc[i]);
totused += nmalloc[i] * (1 << (i + 3));
}
xprintf("\n\tTotal in use: %d, total free: %d\n",
totused, totfree);
xprintf("\tAllocated memory from 0x%lx to 0x%lx. Real top at 0x%lx\n",
membot, memtop, (char *) sbrk(0));
#else
xprintf("Allocated memory from 0x%lx to 0x%lx (%ld).\n",
(long)membot, (long)(memtop = (char *) sbrk(0)),(long)(memtop - membot));
#endif /* SYSMALLOC */
}
#endif /* pdp11 */