Mac/mwerks/malloc/malloc.c

   1 /*
   2  * Attempt at a memory allocator for the Mac, Jack Jansen, CWI, 1995-1997.
   3  *
   4  * Code adapted from BSD malloc, which is:
   5  *
   6  * Copyright (c) 1983 Regents of the University of California.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  */
  37
  38 #if defined(LIBC_SCCS) && !defined(lint)
  39 /*static char *sccsid = "from: @(#)malloc.c     5.11 (Berkeley) 2/23/91";*/
  40 static char *rcsid = "$Id$";
  41 #endif /* LIBC_SCCS and not lint */
  42
  43 /*
  44  * malloc.c (Caltech) 2/21/82
  45  * Chris Kingsley, kingsley@cit-20. Modified by Jack Jansen, CWI.
  46  *
  47  * This is a very fast storage allocator.  It allocates blocks of a small
  48  * number of different sizes, and keeps free lists of each size.  Blocks that
  49  * don't exactly fit are passed up to the next larger size.
  50  *
  51  * Blocks over a certain size are directly allocated by calling NewPtr.
  52  *
  53  */
  54
  55 #ifdef USE_MALLOC_DEBUG
  56 /* You may also selectively enable some of these (but some are interdependent) */
  57 #define DEBUG
  58 #define DEBUG2
  59 #define MSTATS
  60 #define RCHECK
  61 #define VCHECK
  62 #endif /* USE_MALLOC_DEBUG */
  63
  64 /*
  65  * Set the next define if you want to return memory that is aligned to 32-byte
  66  * boundaries. This allows 604 (and, to a lesser extent, any PPC) programs to
  67  * make better use of the L1 cache.
  68  */
  69 /* #define USE_CACHE_ALIGNED 8  /* The alignment (in 4-byte words) */
  70
  71 typedef unsigned char u_char;
  72 typedef unsigned long u_long;
  73 typedef unsigned int u_int;
  74 typedef unsigned short u_short;
  75 typedef u_long caddr_t;
  76
  77 #include <Memory.h>
  78 #include <stdlib.h>
  79 #include <string.h>
  80
  81 #define NULL 0
  82
  83 static void morecore();
  84
  85 /*
  86  * The overhead on a block is at least 4 bytes.  When free, this space
  87  * contains a pointer to the next free block, and the bottom two bits must
  88  * be zero.  When in use, the first byte is set to MAGIC, and the second
  89  * byte is the size index.  The remaining bytes are for alignment.
  90  * If range checking is enabled then a second word holds the size of the
  91  * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
  92  * The order of elements is critical: ov_magic must overlay the low order
  93  * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
  94  */
  95 union   overhead {
  96         union   overhead *ov_next;      /* when free */
  97         struct {
  98                 u_char  ovu_magic0;     /* magic number */
  99                 u_char  ovu_index;      /* bucket # */
 100                 u_char  ovu_unused;     /* unused */
 101                 u_char  ovu_magic1;     /* other magic number */
 102 #ifdef RCHECK
 103                 u_short ovu_rmagic;     /* range magic number */
 104                 u_long  ovu_size;       /* actual block size */
 105 #endif
 106         } ovu;
 107 #define ov_magic0       ovu.ovu_magic0
 108 #define ov_magic1       ovu.ovu_magic1
 109 #define ov_index        ovu.ovu_index
 110 #define ov_rmagic       ovu.ovu_rmagic
 111 #define ov_size         ovu.ovu_size
 112 #ifdef USE_CACHE_ALIGNED
 113         struct cachealigner {
 114                 u_long  ovalign[USE_CACHE_ALIGNED];
 115         } ovu_aligner;
 116 #endif /* USE_CACHE_ALIGN */
 117 };
 118
 119 #define MAGIC           0xef            /* magic # on accounting info */
 120 #define RMAGIC          0x5555          /* magic # on range info */
 121
 122 #ifdef RCHECK
 123 #define RSLOP           sizeof (u_short)
 124 #else
 125 #define RSLOP           0
 126 #endif
 127
 128 #define OVERHEAD (sizeof(union overhead) + RSLOP)
 129
 130 /*
 131  * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
 132  * smallest allocatable block is 8 bytes.  The overhead information
 133  * precedes the data area returned to the user.
 134  */
 135 #define NBUCKETS 11
 136 #define MAXMALLOC (1<<(NBUCKETS+2))
 137 static  union overhead *nextf[NBUCKETS];
 138
 139 #ifdef MSTATS
 140 /*
 141  * nmalloc[i] is the difference between the number of mallocs and frees
 142  * for a given block size.
 143  */
 144 static  u_int nmalloc[NBUCKETS+1];
 145 #include <stdio.h>
 146 #endif
 147
 148 #if defined(DEBUG) || defined(RCHECK) || defined(DEBUG2)
 149 #define ASSERT(p)   if (!(p)) botch(# p)
 150 #include <stdio.h>
 151 static
 152 botch(s)
 153         char *s;
 154 {
 155         fprintf(stderr, "\r\nmalloc assertion botched: %s\r\n", s);
 156         (void) fflush(stderr);          /* just in case user buffered it */
 157         abort();
 158 }
 159 #else
 160 #define ASSERT(p)
 161 #endif
 162
 163 void *
 164 malloc(nbytes)
 165         size_t nbytes;
 166 {
 167         register union overhead *op;
 168         register long bucket;
 169         register unsigned amt;
 170
 171         /*
 172         ** First the simple case: we simple allocate big blocks directly
 173         */
 174         if ( nbytes + OVERHEAD >= MAXMALLOC ) {
 175                 op = (union overhead *)NewPtr(nbytes+OVERHEAD);
 176                 if ( op == NULL )
 177                         return NULL;
 178                 op->ov_magic0 = op->ov_magic1 = MAGIC;
 179                 op->ov_index = 0xff;
 180 #ifdef MSTATS
 181                 nmalloc[NBUCKETS]++;
 182 #endif
 183 #ifdef RCHECK
 184                 /*
 185                  * Record allocated size of block and
 186                  * bound space with magic numbers.
 187                  */
 188                 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 189                 op->ov_rmagic = RMAGIC;
 190                 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 191 #endif
 192                 return (void *)(op+1);
 193         }
 194         /*
 195          * Convert amount of memory requested into closest block size
 196          * stored in hash buckets which satisfies request.
 197          * Account for space used per block for accounting.
 198          */
 199 #ifndef RCHECK
 200         amt = 8;        /* size of first bucket */
 201         bucket = 0;
 202 #else
 203         amt = 16;       /* size of first bucket */
 204         bucket = 1;
 205 #endif
 206         while (nbytes + OVERHEAD > amt) {
 207                 amt <<= 1;
 208                 if (amt == 0)
 209                         return (NULL);
 210                 bucket++;
 211         }
 212 #ifdef DEBUG2
 213         ASSERT( bucket < NBUCKETS );
 214 #endif
 215         /*
 216          * If nothing in hash bucket right now,
 217          * request more memory from the system.
 218          */
 219         if ((op = nextf[bucket]) == NULL) {
 220                 morecore(bucket);
 221                 if ((op = nextf[bucket]) == NULL)
 222                         return (NULL);
 223         }
 224         /* remove from linked list */
 225         nextf[bucket] = op->ov_next;
 226         op->ov_magic0 = op->ov_magic1 = MAGIC;
 227         op->ov_index = bucket;
 228 #ifdef MSTATS
 229         nmalloc[bucket]++;
 230 #endif
 231 #ifdef RCHECK
 232         /*
 233          * Record allocated size of block and
 234          * bound space with magic numbers.
 235          */
 236         op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 237         op->ov_rmagic = RMAGIC;
 238         *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 239 #endif
 240 #ifdef VCHECK
 241         memset((char *)(op+1), 0x41, nbytes);
 242 #endif
 243         return ((char *)(op + 1));
 244 }
 245
 246 /*
 247  * Allocate more memory to the indicated bucket.
 248  */
 249 static void
 250 morecore(bucket)
 251         int bucket;
 252 {
 253         register union overhead *op;
 254         register long sz;               /* size of desired block */
 255         long amt;                       /* amount to allocate */
 256         int nblks;                      /* how many blocks we get */
 257
 258         /*
 259          * sbrk_size <= 0 only for big, FLUFFY, requests (about
 260          * 2^30 bytes on a VAX, I think) or for a negative arg.
 261          */
 262         sz = 1 << (bucket + 3);
 263 #ifdef DEBUG2
 264         ASSERT(sz > 0);
 265 #endif
 266         amt = MAXMALLOC;
 267         nblks = amt / sz;
 268 #ifdef DEBUG2
 269         ASSERT(nblks*sz == amt);
 270 #endif
 271 #ifdef USE_CACHE_ALIGNED
 272         op = (union overhead *)NewPtr(amt+4*USE_CACHE_ALIGNED);
 273 #else
 274         op = (union overhead *)NewPtr(amt);
 275 #endif
 276         /* no more room! */
 277         if (op == NULL)
 278                 return;
 279 #ifdef USE_CACHE_ALIGNED
 280 #define ALIGN_MASK (4*USE_CACHE_ALIGNED-1)
 281         while ((long)op & ALIGN_MASK )
 282                 op = (union overhead *)((long)op+1);
 283 #endif /* USE_CACHE_ALIGNED */
 284         /*
 285          * Add new memory allocated to that on
 286          * free list for this hash bucket.
 287          */
 288         nextf[bucket] = op;
 289         while (--nblks > 0) {
 290                 op->ov_next = (union overhead *)((caddr_t)op + sz);
 291                 op = (union overhead *)((caddr_t)op + sz);
 292         }
 293         op->ov_next = (union overhead *)NULL;
 294 }
 295
 296 void
 297 free(cp)
 298         void *cp;
 299 {
 300         register long size;
 301         register union overhead *op;
 302
 303         if (cp == NULL)
 304                 return;
 305         op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
 306 #ifdef DEBUG
 307         ASSERT(op->ov_magic0 == MAGIC);         /* make sure it was in use */
 308         ASSERT(op->ov_magic1 == MAGIC);
 309 #else
 310         if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
 311                 return;                         /* sanity */
 312 #endif
 313 #ifdef RCHECK
 314         ASSERT(op->ov_rmagic == RMAGIC);
 315         ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
 316 #endif
 317 #ifdef VCHECK
 318         memset(cp, 43, op->ov_size);
 319 #endif
 320         size = op->ov_index;
 321         if ( size == 0xff ) {
 322 #ifdef MSTATS
 323                 nmalloc[NBUCKETS]--;
 324 #endif
 325                 DisposePtr((Ptr)op);
 326                 return;
 327         }
 328         ASSERT(size < NBUCKETS);
 329         op->ov_next = nextf[size];      /* also clobbers ov_magic */
 330         nextf[size] = op;
 331 #ifdef MSTATS
 332         nmalloc[size]--;
 333 #endif
 334 }
 335
 336 void *
 337 realloc(cp, nbytes)
 338         void *cp;
 339         size_t nbytes;
 340 {
 341         int i;
 342         union overhead *op;
 343         int expensive;
 344         u_long maxsize;
 345
 346         if (cp == NULL)
 347                 return (malloc(nbytes));
 348         op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
 349 #ifdef DEBUG
 350         ASSERT(op->ov_magic0 == MAGIC);         /* make sure it was in use */
 351         ASSERT(op->ov_magic1 == MAGIC);
 352 #else
 353         if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
 354                 return NULL;                            /* sanity */
 355 #endif
 356 #ifdef RCHECK
 357         ASSERT(op->ov_rmagic == RMAGIC);
 358         ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
 359 #endif
 360         i = op->ov_index;
 361         /*
 362         ** First the malloc/copy cases
 363         */
 364         expensive = 0;
 365         if ( i == 0xff ) {
 366                 /* Big block. See if it has to stay big */
 367                 if (nbytes+OVERHEAD > MAXMALLOC) {
 368                         /* Yup, try to resize it first */
 369                         SetPtrSize((Ptr)op, nbytes+OVERHEAD);
 370                         if ( MemError() == 0 ) {
 371 #ifdef RCHECK
 372                                 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 373                                 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 374 #endif
 375                                 return cp;
 376                         }
 377                         /* Nope, failed. Take the long way */
 378                 }
 379                 maxsize = GetPtrSize((Ptr)op);
 380                 expensive = 1;
 381         } else {
 382                 maxsize = 1 << (i+3);
 383                 if ( nbytes + OVERHEAD > maxsize )
 384                         expensive = 1;
 385                 else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) )
 386                         expensive = 1;
 387         }
 388         if ( expensive ) {
 389                 void *newp;
 390
 391                 newp = malloc(nbytes);
 392                 if ( newp == NULL ) {
 393                         return NULL;
 394                 }
 395                 maxsize -= OVERHEAD;
 396                 if ( maxsize < nbytes )
 397                         nbytes = maxsize;
 398                 memcpy(newp, cp, nbytes);
 399                 free(cp);
 400                 return newp;
 401         }
 402         /*
 403         ** Ok, we don't have to copy, it fits as-is
 404         */
 405 #ifdef RCHECK
 406         op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 407         *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 408 #endif
 409         return(cp);
 410 }
 411
 412
 413 #ifdef MSTATS
 414 /*
 415  * mstats - print out statistics about malloc
 416  *
 417  * Prints two lines of numbers, one showing the length of the free list
 418  * for each size category, the second showing the number of mallocs -
 419  * frees for each size category.
 420  */
 421 mstats(s)
 422         char *s;
 423 {
 424         register int i, j;
 425         register union overhead *p;
 426         int totfree = 0,
 427         totused = 0;
 428
 429         fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
 430         for (i = 0; i < NBUCKETS; i++) {
 431                 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
 432                         ;
 433                 fprintf(stderr, " %d", j);
 434                 totfree += j * (1 << (i + 3));
 435         }
 436         fprintf(stderr, "\nused:\t");
 437         for (i = 0; i < NBUCKETS; i++) {
 438                 fprintf(stderr, " %d", nmalloc[i]);
 439                 totused += nmalloc[i] * (1 << (i + 3));
 440         }
 441         fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
 442             totused, totfree);
 443         fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", MAXMALLOC, nmalloc[NBUCKETS]);
 444 }
 445 #endif