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 #ifndef NULL
  82 #define NULL 0
  83 #endif
  84
  85 static void morecore();
  86
  87 /*
  88  * The overhead on a block is at least 4 bytes.  When free, this space
  89  * contains a pointer to the next free block, and the bottom two bits must
  90  * be zero.  When in use, the first byte is set to MAGIC, and the second
  91  * byte is the size index.  The remaining bytes are for alignment.
  92  * If range checking is enabled then a second word holds the size of the
  93  * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
  94  * The order of elements is critical: ov_magic must overlay the low order
  95  * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
  96  */
  97 union   overhead {
  98         union   overhead *ov_next;      /* when free */
  99         struct {
 100                 u_char  ovu_magic0;     /* magic number */
 101                 u_char  ovu_index;      /* bucket # */
 102                 u_char  ovu_unused;     /* unused */
 103                 u_char  ovu_magic1;     /* other magic number */
 104 #ifdef RCHECK
 105                 u_short ovu_rmagic;     /* range magic number */
 106                 u_long  ovu_size;       /* actual block size */
 107 #endif
 108         } ovu;
 109 #define ov_magic0       ovu.ovu_magic0
 110 #define ov_magic1       ovu.ovu_magic1
 111 #define ov_index        ovu.ovu_index
 112 #define ov_rmagic       ovu.ovu_rmagic
 113 #define ov_size         ovu.ovu_size
 114 #ifdef USE_CACHE_ALIGNED
 115         struct cachealigner {
 116                 u_long  ovalign[USE_CACHE_ALIGNED];
 117         } ovu_aligner;
 118 #endif /* USE_CACHE_ALIGN */
 119 };
 120
 121 #define MAGIC           0xef            /* magic # on accounting info */
 122 #define RMAGIC          0x5555          /* magic # on range info */
 123
 124 #ifdef RCHECK
 125 #define RSLOP           sizeof (u_short)
 126 #else
 127 #define RSLOP           0
 128 #endif
 129
 130 #define OVERHEAD (sizeof(union overhead) + RSLOP)
 131
 132 /*
 133  * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
 134  * smallest allocatable block is 8 bytes.  The overhead information
 135  * precedes the data area returned to the user.
 136  */
 137 #define NBUCKETS 11
 138 #define MAXMALLOC (1<<(NBUCKETS+2))
 139 static  union overhead *nextf[NBUCKETS];
 140
 141 #ifdef MSTATS
 142 /*
 143  * nmalloc[i] is the difference between the number of mallocs and frees
 144  * for a given block size.
 145  */
 146 static  u_int nmalloc[NBUCKETS+1];
 147 #include <stdio.h>
 148 #endif
 149
 150 #if defined(DEBUG) || defined(RCHECK) || defined(DEBUG2)
 151 #define ASSERT(p)   if (!(p)) botch(# p)
 152 #include <stdio.h>
 153 static
 154 botch(s)
 155         char *s;
 156 {
 157         fprintf(stderr, "\r\nmalloc assertion botched: %s\r\n", s);
 158         (void) fflush(stderr);          /* just in case user buffered it */
 159         abort();
 160 }
 161 #else
 162 #define ASSERT(p)
 163 #endif
 164
 165 void *
 166 malloc(nbytes)
 167         size_t nbytes;
 168 {
 169         register union overhead *op;
 170         register long bucket;
 171         register unsigned amt;
 172
 173         /*
 174         ** First the simple case: we simple allocate big blocks directly
 175         */
 176         if ( nbytes + OVERHEAD >= MAXMALLOC ) {
 177                 op = (union overhead *)NewPtr(nbytes+OVERHEAD);
 178                 if ( op == NULL )
 179                         return NULL;
 180                 op->ov_magic0 = op->ov_magic1 = MAGIC;
 181                 op->ov_index = 0xff;
 182 #ifdef MSTATS
 183                 nmalloc[NBUCKETS]++;
 184 #endif
 185 #ifdef RCHECK
 186                 /*
 187                  * Record allocated size of block and
 188                  * bound space with magic numbers.
 189                  */
 190                 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 191                 op->ov_rmagic = RMAGIC;
 192                 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 193 #endif
 194                 return (void *)(op+1);
 195         }
 196         /*
 197          * Convert amount of memory requested into closest block size
 198          * stored in hash buckets which satisfies request.
 199          * Account for space used per block for accounting.
 200          */
 201 #ifndef RCHECK
 202         amt = 8;        /* size of first bucket */
 203         bucket = 0;
 204 #else
 205         amt = 16;       /* size of first bucket */
 206         bucket = 1;
 207 #endif
 208         while (nbytes + OVERHEAD > amt) {
 209                 amt <<= 1;
 210                 if (amt == 0)
 211                         return (NULL);
 212                 bucket++;
 213         }
 214 #ifdef DEBUG2
 215         ASSERT( bucket < NBUCKETS );
 216 #endif
 217         /*
 218          * If nothing in hash bucket right now,
 219          * request more memory from the system.
 220          */
 221         if ((op = nextf[bucket]) == NULL) {
 222                 morecore(bucket);
 223                 if ((op = nextf[bucket]) == NULL)
 224                         return (NULL);
 225         }
 226         /* remove from linked list */
 227         nextf[bucket] = op->ov_next;
 228         op->ov_magic0 = op->ov_magic1 = MAGIC;
 229         op->ov_index = bucket;
 230 #ifdef MSTATS
 231         nmalloc[bucket]++;
 232 #endif
 233 #ifdef RCHECK
 234         /*
 235          * Record allocated size of block and
 236          * bound space with magic numbers.
 237          */
 238         op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 239         op->ov_rmagic = RMAGIC;
 240         *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 241 #endif
 242 #ifdef VCHECK
 243         memset((char *)(op+1), 0x41, nbytes);
 244 #endif
 245         return ((char *)(op + 1));
 246 }
 247
 248 /*
 249  * Allocate more memory to the indicated bucket.
 250  */
 251 static void
 252 morecore(bucket)
 253         int bucket;
 254 {
 255         register union overhead *op;
 256         register long sz;               /* size of desired block */
 257         long amt;                       /* amount to allocate */
 258         int nblks;                      /* how many blocks we get */
 259
 260         /*
 261          * sbrk_size <= 0 only for big, FLUFFY, requests (about
 262          * 2^30 bytes on a VAX, I think) or for a negative arg.
 263          */
 264         sz = 1 << (bucket + 3);
 265 #ifdef DEBUG2
 266         ASSERT(sz > 0);
 267 #endif
 268         amt = MAXMALLOC;
 269         nblks = amt / sz;
 270 #ifdef DEBUG2
 271         ASSERT(nblks*sz == amt);
 272 #endif
 273 #ifdef USE_CACHE_ALIGNED
 274         op = (union overhead *)NewPtr(amt+4*USE_CACHE_ALIGNED);
 275 #else
 276         op = (union overhead *)NewPtr(amt);
 277 #endif
 278         /* no more room! */
 279         if (op == NULL)
 280                 return;
 281 #ifdef USE_CACHE_ALIGNED
 282 #define ALIGN_MASK (4*USE_CACHE_ALIGNED-1)
 283         while ((long)op & ALIGN_MASK )
 284                 op = (union overhead *)((long)op+1);
 285 #endif /* USE_CACHE_ALIGNED */
 286         /*
 287          * Add new memory allocated to that on
 288          * free list for this hash bucket.
 289          */
 290         nextf[bucket] = op;
 291         while (--nblks > 0) {
 292                 op->ov_next = (union overhead *)((caddr_t)op + sz);
 293                 op = (union overhead *)((caddr_t)op + sz);
 294         }
 295         op->ov_next = (union overhead *)NULL;
 296 }
 297
 298 void
 299 free(cp)
 300         void *cp;
 301 {
 302         register long size;
 303         register union overhead *op;
 304
 305         if (cp == NULL)
 306                 return;
 307         op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
 308 #ifdef DEBUG
 309         ASSERT(op->ov_magic0 == MAGIC);         /* make sure it was in use */
 310         ASSERT(op->ov_magic1 == MAGIC);
 311 #else
 312         if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
 313                 return;                         /* sanity */
 314 #endif
 315 #ifdef RCHECK
 316         ASSERT(op->ov_rmagic == RMAGIC);
 317         ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
 318 #endif
 319 #ifdef VCHECK
 320         memset(cp, 43, op->ov_size);
 321 #endif
 322         size = op->ov_index;
 323         if ( size == 0xff ) {
 324 #ifdef MSTATS
 325                 nmalloc[NBUCKETS]--;
 326 #endif
 327                 DisposePtr((Ptr)op);
 328                 return;
 329         }
 330         ASSERT(size < NBUCKETS);
 331         op->ov_next = nextf[size];      /* also clobbers ov_magic */
 332         nextf[size] = op;
 333 #ifdef MSTATS
 334         nmalloc[size]--;
 335 #endif
 336 }
 337
 338 void *
 339 realloc(cp, nbytes)
 340         void *cp;
 341         size_t nbytes;
 342 {
 343         int i;
 344         union overhead *op;
 345         int expensive;
 346         u_long maxsize;
 347
 348         if (cp == NULL)
 349                 return (malloc(nbytes));
 350         op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
 351 #ifdef DEBUG
 352         ASSERT(op->ov_magic0 == MAGIC);         /* make sure it was in use */
 353         ASSERT(op->ov_magic1 == MAGIC);
 354 #else
 355         if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
 356                 return NULL;                            /* sanity */
 357 #endif
 358 #ifdef RCHECK
 359         ASSERT(op->ov_rmagic == RMAGIC);
 360         ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
 361 #endif
 362         i = op->ov_index;
 363         /*
 364         ** First the malloc/copy cases
 365         */
 366         expensive = 0;
 367         if ( i == 0xff ) {
 368                 /* Big block. See if it has to stay big */
 369                 if (nbytes+OVERHEAD > MAXMALLOC) {
 370                         /* Yup, try to resize it first */
 371                         SetPtrSize((Ptr)op, nbytes+OVERHEAD);
 372                         if ( MemError() == 0 ) {
 373 #ifdef RCHECK
 374                                 op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 375                                 *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 376 #endif
 377                                 return cp;
 378                         }
 379                         /* Nope, failed. Take the long way */
 380                 }
 381                 maxsize = GetPtrSize((Ptr)op);
 382                 expensive = 1;
 383         } else {
 384                 maxsize = 1 << (i+3);
 385                 if ( nbytes + OVERHEAD > maxsize )
 386                         expensive = 1;
 387                 else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) )
 388                         expensive = 1;
 389         }
 390         if ( expensive ) {
 391                 void *newp;
 392
 393                 newp = malloc(nbytes);
 394                 if ( newp == NULL ) {
 395                         return NULL;
 396                 }
 397                 maxsize -= OVERHEAD;
 398                 if ( maxsize < nbytes )
 399                         nbytes = maxsize;
 400                 memcpy(newp, cp, nbytes);
 401                 free(cp);
 402                 return newp;
 403         }
 404         /*
 405         ** Ok, we don't have to copy, it fits as-is
 406         */
 407 #ifdef RCHECK
 408         op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
 409         *(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
 410 #endif
 411         return(cp);
 412 }
 413
 414
 415 #ifdef MSTATS
 416 /*
 417  * mstats - print out statistics about malloc
 418  *
 419  * Prints two lines of numbers, one showing the length of the free list
 420  * for each size category, the second showing the number of mallocs -
 421  * frees for each size category.
 422  */
 423 mstats(s)
 424         char *s;
 425 {
 426         register int i, j;
 427         register union overhead *p;
 428         int totfree = 0,
 429         totused = 0;
 430
 431         fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
 432         for (i = 0; i < NBUCKETS; i++) {
 433                 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
 434                         ;
 435                 fprintf(stderr, " %d", j);
 436                 totfree += j * (1 << (i + 3));
 437         }
 438         fprintf(stderr, "\nused:\t");
 439         for (i = 0; i < NBUCKETS; i++) {
 440                 fprintf(stderr, " %d", nmalloc[i]);
 441                 totused += nmalloc[i] * (1 << (i + 3));
 442         }
 443         fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
 444             totused, totfree);
 445         fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", MAXMALLOC, nmalloc[NBUCKETS]);
 446 }
 447 #endif