![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to alloc.c CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Research Unix] / researchv9 / X11 / src / X.V11R1 / clients / xmh|
Return to alloc.c CVS log | Up to [Research Unix] / researchv9 / X11 / src / X.V11R1 / clients / xmh |
1.1 ! root 1: /* $Header: alloc.c,v 1.1 87/09/11 08:18:47 toddb Exp $ */ ! 2: #ifndef lint ! 3: static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83"; ! 4: #endif ! 5: ! 6: /****************************************************************************** ! 7: This is the standard malloc routines, with some extra debugging stuff so I'll ! 8: know when I trash memory somewhere. ! 9: ******************************************************************************/ ! 10: ! 11: #define debug ! 12: #define RCHECK ! 13: ! 14: /* ! 15: * malloc.c (Caltech) 2/21/82 ! 16: * Chris Kingsley, kingsley@cit-20. ! 17: * ! 18: * This is a very fast storage allocator. It allocates blocks of a small ! 19: * number of different sizes, and keeps free lists of each size. Blocks that ! 20: * don't exactly fit are passed up to the next larger size. In this ! 21: * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long. ! 22: * This is designed for use in a program that uses vast quantities of memory, ! 23: * but bombs when it runs out. ! 24: */ ! 25: ! 26: #include <sys/types.h> ! 27: ! 28: #define NULL 0 ! 29: ! 30: /* ! 31: * The overhead on a block is at least 4 bytes. When free, this space ! 32: * contains a pointer to the next free block, and the bottom two bits must ! 33: * be zero. When in use, the first byte is set to MAGIC, and the second ! 34: * byte is the size index. The remaining bytes are for alignment. ! 35: * If range checking is enabled and the size of the block fits ! 36: * in two bytes, then the top two bytes hold the size of the requested block ! 37: * plus the range checking words, and the header word MINUS ONE. ! 38: */ ! 39: union overhead { ! 40: union overhead *ov_next; /* when free */ ! 41: struct { ! 42: u_char ovu_magic; /* magic number */ ! 43: u_char ovu_index; /* bucket # */ ! 44: #ifdef RCHECK ! 45: u_short ovu_size; /* actual block size */ ! 46: u_int ovu_rmagic; /* range magic number */ ! 47: #endif ! 48: } ovu; ! 49: #define ov_magic ovu.ovu_magic ! 50: #define ov_index ovu.ovu_index ! 51: #define ov_size ovu.ovu_size ! 52: #define ov_rmagic ovu.ovu_rmagic ! 53: }; ! 54: ! 55: #define MAGIC 0xff /* magic # on accounting info */ ! 56: #define RMAGIC 0x55555555 /* magic # on range info */ ! 57: #ifdef RCHECK ! 58: #define RSLOP sizeof (u_int) ! 59: #else ! 60: #define RSLOP 0 ! 61: #endif ! 62: ! 63: /* ! 64: * nextf[i] is the pointer to the next free block of size 2^(i+3). The ! 65: * smallest allocatable block is 8 bytes. The overhead information ! 66: * precedes the data area returned to the user. ! 67: */ ! 68: #define NBUCKETS 30 ! 69: static union overhead *nextf[NBUCKETS]; ! 70: extern char *sbrk(); ! 71: ! 72: #ifdef MSTATS ! 73: /* ! 74: * nmalloc[i] is the difference between the number of mallocs and frees ! 75: * for a given block size. ! 76: */ ! 77: static u_int nmalloc[NBUCKETS]; ! 78: #include <stdio.h> ! 79: #endif ! 80: ! 81: #ifdef debug ! 82: #define ASSERT(p) if (!(p)) botch("p"); else ! 83: static ! 84: botch(s) ! 85: char *s; ! 86: { ! 87: ! 88: (void)printf("assertion botched: %s\n", s); ! 89: (void)abort(); ! 90: } ! 91: #else ! 92: #define ASSERT(p) ! 93: #endif ! 94: ! 95: char * ! 96: malloc(nbytes) ! 97: register unsigned nbytes; ! 98: { ! 99: register union overhead *p; ! 100: register int bucket = 0; ! 101: register unsigned shiftr; ! 102: ! 103: /* ! 104: * Convert amount of memory requested into ! 105: * closest block size stored in hash buckets ! 106: * which satisfies request. Account for ! 107: * space used per block for accounting. ! 108: */ ! 109: nbytes += sizeof (union overhead) + RSLOP; ! 110: nbytes = (nbytes + 3) &~ 3; ! 111: shiftr = (nbytes - 1) >> 2; ! 112: /* apart from this loop, this is O(1) */ ! 113: while (shiftr >>= 1) ! 114: bucket++; ! 115: /* ! 116: * If nothing in hash bucket right now, ! 117: * request more memory from the system. ! 118: */ ! 119: if (nextf[bucket] == NULL) ! 120: morecore(bucket); ! 121: if ((p = (union overhead *)nextf[bucket]) == NULL) ! 122: return (NULL); ! 123: /* remove from linked list */ ! 124: nextf[bucket] = nextf[bucket]->ov_next; ! 125: p->ov_magic = MAGIC; ! 126: p->ov_index= bucket; ! 127: #ifdef MSTATS ! 128: nmalloc[bucket]++; ! 129: #endif ! 130: #ifdef RCHECK ! 131: /* ! 132: * Record allocated size of block and ! 133: * bound space with magic numbers. ! 134: */ ! 135: if (nbytes <= 0x10000) ! 136: p->ov_size = nbytes - 1; ! 137: p->ov_rmagic = RMAGIC; ! 138: *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC; ! 139: #endif ! 140: return ((char *)(p + 1)); ! 141: } ! 142: ! 143: /* ! 144: * Allocate more memory to the indicated bucket. ! 145: */ ! 146: static ! 147: morecore(bucket) ! 148: register bucket; ! 149: { ! 150: register union overhead *op; ! 151: register int rnu; /* 2^rnu bytes will be requested */ ! 152: register int nblks; /* become nblks blocks of the desired size */ ! 153: register int siz; ! 154: ! 155: if (nextf[bucket]) ! 156: return; ! 157: /* ! 158: * Insure memory is allocated ! 159: * on a page boundary. Should ! 160: * make getpageize call? ! 161: */ ! 162: op = (union overhead *)sbrk(0); ! 163: if ((int)op & 0x3ff) ! 164: (void)sbrk(1024 - ((int)op & 0x3ff)); ! 165: /* take 2k unless the block is bigger than that */ ! 166: rnu = (bucket <= 8) ? 11 : bucket + 3; ! 167: nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */ ! 168: if (rnu < bucket) ! 169: rnu = bucket; ! 170: op = (union overhead *)sbrk(1 << rnu); ! 171: /* no more room! */ ! 172: if ((int)op == -1) ! 173: return; ! 174: /* ! 175: * Round up to minimum allocation size boundary ! 176: * and deduct from block count to reflect. ! 177: */ ! 178: if ((int)op & 7) { ! 179: op = (union overhead *)(((int)op + 8) &~ 7); ! 180: nblks--; ! 181: } ! 182: /* ! 183: * Add new memory allocated to that on ! 184: * free list for this hash bucket. ! 185: */ ! 186: nextf[bucket] = op; ! 187: siz = 1 << (bucket + 3); ! 188: while (--nblks > 0) { ! 189: op->ov_next = (union overhead *)((caddr_t)op + siz); ! 190: op = (union overhead *)((caddr_t)op + siz); ! 191: } ! 192: } ! 193: ! 194: void free(cp) ! 195: char *cp; ! 196: { ! 197: register int size; ! 198: register union overhead *op; ! 199: ! 200: if (cp == NULL) ! 201: return; ! 202: op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); ! 203: #ifdef debug ! 204: ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */ ! 205: #else ! 206: if (op->ov_magic != MAGIC) ! 207: return; /* sanity */ ! 208: #endif ! 209: #ifdef RCHECK ! 210: ASSERT(op->ov_rmagic == RMAGIC); ! 211: if (op->ov_index <= 13) ! 212: ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC); ! 213: #endif ! 214: ASSERT(op->ov_index < NBUCKETS); ! 215: size = op->ov_index; ! 216: op->ov_next = nextf[size]; ! 217: nextf[size] = op; ! 218: #ifdef MSTATS ! 219: nmalloc[size]--; ! 220: #endif ! 221: } ! 222: ! 223: /* ! 224: * When a program attempts "storage compaction" as mentioned in the ! 225: * old malloc man page, it realloc's an already freed block. Usually ! 226: * this is the last block it freed; occasionally it might be farther ! 227: * back. We have to search all the free lists for the block in order ! 228: * to determine its bucket: 1st we make one pass thru the lists ! 229: * checking only the first block in each; if that fails we search ! 230: * ``realloc_srchlen'' blocks in each list for a match (the variable ! 231: * is extern so the caller can modify it). If that fails we just copy ! 232: * however many bytes was given to realloc() and hope it's not huge. ! 233: */ ! 234: int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */ ! 235: ! 236: char * ! 237: realloc(cp, nbytes) ! 238: char *cp; ! 239: unsigned nbytes; ! 240: { ! 241: register u_int onb; ! 242: union overhead *op; ! 243: char *res; ! 244: register int i; ! 245: int was_alloced = 0; ! 246: ! 247: if (cp == NULL) ! 248: return (malloc(nbytes)); ! 249: op = (union overhead *)((caddr_t)cp - sizeof (union overhead)); ! 250: if (op->ov_magic == MAGIC) { ! 251: was_alloced++; ! 252: i = op->ov_index; ! 253: } else { ! 254: /* ! 255: * Already free, doing "compaction". ! 256: * ! 257: * Search for the old block of memory on the ! 258: * free list. First, check the most common ! 259: * case (last element free'd), then (this failing) ! 260: * the last ``realloc_srchlen'' items free'd. ! 261: * If all lookups fail, then assume the size of ! 262: * the memory block being realloc'd is the ! 263: * smallest possible. ! 264: */ ! 265: if ((i = findbucket(op, 1)) < 0 && ! 266: (i = findbucket(op, realloc_srchlen)) < 0) ! 267: i = 0; ! 268: } ! 269: onb = (1 << (i + 3)) - sizeof (*op) - RSLOP; ! 270: /* avoid the copy if same size block */ ! 271: #ifdef NOTDEF ! 272: if (was_alloced && ! 273: nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) { ! 274: #ifdef RCHECK ! 275: unsigned sz; ! 276: sz = (nbytes + sizeof(union overhead) + RSLOP + 3) &~ 3; ! 277: if (sz <= 0x10000) ! 278: op->ov_size = sz - 1; ! 279: *((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC; ! 280: #endif ! 281: return(cp); ! 282: } ! 283: #endif NOTDEF ! 284: if ((res = malloc(nbytes)) == NULL) ! 285: return (NULL); ! 286: if (cp != res) /* common optimization */ ! 287: (void)bcopy(cp, res, (int) ((nbytes < onb) ? nbytes : onb)); ! 288: if (was_alloced) ! 289: free(cp); ! 290: return (res); ! 291: } ! 292: ! 293: /* ! 294: * Search ``srchlen'' elements of each free list for a block whose ! 295: * header starts at ``freep''. If srchlen is -1 search the whole list. ! 296: * Return bucket number, or -1 if not found. ! 297: */ ! 298: static ! 299: findbucket(freep, srchlen) ! 300: union overhead *freep; ! 301: int srchlen; ! 302: { ! 303: register union overhead *p; ! 304: register int i, j; ! 305: ! 306: for (i = 0; i < NBUCKETS; i++) { ! 307: j = 0; ! 308: for (p = nextf[i]; p && j != srchlen; p = p->ov_next) { ! 309: if (p == freep) ! 310: return (i); ! 311: j++; ! 312: } ! 313: } ! 314: return (-1); ! 315: } ! 316: ! 317: #ifdef MSTATS ! 318: /* ! 319: * mstats - print out statistics about malloc ! 320: * ! 321: * Prints two lines of numbers, one showing the length of the free list ! 322: * for each size category, the second showing the number of mallocs - ! 323: * frees for each size category. ! 324: */ ! 325: mstats(s) ! 326: char *s; ! 327: { ! 328: register int i, j; ! 329: register union overhead *p; ! 330: int totfree = 0, ! 331: totused = 0; ! 332: ! 333: (void)fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s); ! 334: for (i = 0; i < NBUCKETS; i++) { ! 335: for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) ! 336: ; ! 337: (void)fprintf(stderr, " %d", j); ! 338: totfree += j * (1 << (i + 3)); ! 339: } ! 340: (void)fprintf(stderr, "\nused:\t"); ! 341: for (i = 0; i < NBUCKETS; i++) { ! 342: (void)fprintf(stderr, " %d", nmalloc[i]); ! 343: totused += nmalloc[i] * (1 << (i + 3)); ! 344: } ! 345: (void)fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n", ! 346: totused, totfree); ! 347: } ! 348: #endif
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.