/* $Xorg: t1malloc.c,v 1.3 2000/08/17 19:46:34 cpqbld Exp $ */ /* Copyright International Business Machines, Corp. 1991 * All Rights Reserved * Copyright Lexmark International, Inc. 1991 * All Rights Reserved * * License to use, copy, modify, and distribute this software and its * documentation for any purpose and without fee is hereby granted, * provided that the above copyright notice appear in all copies and that * both that copyright notice and this permission notice appear in * supporting documentation, and that the name of IBM or Lexmark not be * used in advertising or publicity pertaining to distribution of the * software without specific, written prior permission. * * IBM AND LEXMARK PROVIDE THIS SOFTWARE "AS IS", WITHOUT ANY WARRANTIES OF * ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO ANY * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, * AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. THE ENTIRE RISK AS TO THE * QUALITY AND PERFORMANCE OF THE SOFTWARE, INCLUDING ANY DUTY TO SUPPORT * OR MAINTAIN, BELONGS TO THE LICENSEE. SHOULD ANY PORTION OF THE * SOFTWARE PROVE DEFECTIVE, THE LICENSEE (NOT IBM OR LEXMARK) ASSUMES THE * ENTIRE COST OF ALL SERVICING, REPAIR AND CORRECTION. IN NO EVENT SHALL * IBM OR LEXMARK BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF * THIS SOFTWARE. */ /* $XFree86: xc/lib/font/Type1/t1malloc.c,v 1.11 2002/02/18 20:51:57 herrb Exp $ */ /* MALLOC CWEB V0004 LOTS */ /* :h1.MALLOC - Fast Memory Allocation This module is meant to provide portable C-style memory allocation routines (malloc/free). &author. Jeffrey B. Lotspiech (lotspiech@almaden.ibm.com) */ #ifdef HAVE_CONFIG_H #include #endif #ifndef FONTMODULE #include #else #include "Xdefs.h" /* Bool declaration */ #include "Xmd.h" /* INT32 declaration */ #include "os.h" #include "xf86_ansic.h" #endif #include "objects.h" /* get #define for Abort() */ /* :h3.Define NULL In the beginning, C compilers made no assumptions about NULL. It was even theoretically possible that NULL would not be 0. ANSI has tied this down a bit. The following definition seems to be the most popular (in terms of reducing compiler complaints), however, if your compiler is unhappy about it, you can redefine it on the command line: */ #ifndef NULL #include #endif /* Of course, NULL is important because xiMalloc() is defined to return NULL when out of memory. :h2.Data Structures Used to Manage Free Memory :h3.The "freeblock" Structure The list of available memory blocks is a doubly-linked list. Each block begins with the following structure: */ struct freeblock { long size; /* number of 'longs' in block, including this header */ struct freeblock *fore; /* forward in doubly-linked list */ struct freeblock *back; /* backward in doubly-linked list */ } ; /* In addition, each free block has a TRAILER that is simply the 'size' repeated. Thus 'size' is found at the beginning of the block and at the end of the block (size-1 longs away). 'size' includes both the header and the trailer. When a block is allocated, its 'size' is turned negative (both at the beginning and at the end). Thus, checking whether two blocks may be combined is very simple. We merely examine both neighboring blocks' size to see if they are positive (and hence available for combination). The memory address returned to the user is therefore one "long" below the size, and one extra "long" is added to the end of the block (beyond what the user requested) to store the trailing size. :h3."firstfree" and "lastfree", the Anchors to the Free List "firstfree" points to the first available free block; "lastfree" points to the end of the chain of available blocks. These are linked together by initialization code; see :hdref refid=addmem.. */ static struct freeblock firstfree = { 0L, NULL, NULL }; static struct freeblock lastfree = { 0L, NULL, NULL }; /* :h3."firstcombined" and "uncombined", Keeping Track of Uncombined Blocks This module is designed to make the combining of adjacent free memory blocks be very fast. Nonetheless, combining blocks is naturally the most expensive part of any memory system. In an X system, it is worthwhile to defer the combination for a while, because frequently we will end up asking for a block of exactly the same size that we recently returned and we can save ourselves some work. "MAXUNCOMBINED" is the maximum number of uncombined blocks that we will allow at any time: */ #define MAXUNCOMBINED 3 /* "firstcombined" is a pointer into the free list. The uncombined blocks are always at the front of the list. "firstcombined" points to the first block that has been combined. */ static struct freeblock *firstcombined = &lastfree; static short uncombined = 0; /* current number of uncombined blocks */ /* Uncombined blocks have a negative 'size'; in this they are like allocated blocks. We store a distinctive hex pattern in 'size' when we combine a block to help us debug: */ #define COMBINED 0xBADBAD /* :h3.DEBUGWORDS - Extra Memory Saved With Each Block for Debug We add 'DEBUGWORDS' words to each allocated block to put interesting debug information: */ #ifndef DEBUGWORDS #define DEBUGWORDS 0 #endif /* :h3.MINEXCESS - Amount of "Excess" We Would be Willing to Ignore When we search the free list to find memory for a user request, we frequently find an area that is bigger than what the user has asked for. Normally we put the remaining words (the excess) back on the free list. However, if the area is just slightly bigger than what the user needs, it is counter-productive to do this, as the small amount recovered tends to hurt by increasing memory fragmentation rather than help by providing more available memory. "MINEXCESS" is the number of words that must be recovered before we would bother to put the excess back on the free list. If there is not enough excess, we just give the user more than he asked for. */ #define MINEXCESS (7 + DEBUGWORDS) /* :h3.Some Flags for Debug */ long AvailableWords = 0; /* number of words available in memory */ char mallocdebug = 0; /* a flag that enables some chatty printf's */ /* :h3.Prototypes of static functions */ static void combine ( void ); static void freeuncombinable ( long *addr, long size ); static void unhook ( struct freeblock *p ); static void dumpchain ( void ); #ifdef notused static void reportarea ( long *area ); #endif /* :h3.whocalledme() - Debug for Memory Leaks This routine is 68000-specific; it copies the value of the application's curOper variable (which is often a pointer to a character string), and the first part of the stack at the time malloc was called into the DEBUGWORDS area reserved with each block. We use it to see who is malloc-ing memory without free-ing it. */ #if DEBUGWORDS static void whocalledme(long *addr, /* address of memory block */ long *stack) /* address of malloc's parameter on stack */ { register long size; /* size of memory block */ register int i; /* loop index */ extern char *curOper; /* ptr to last operator (kept by appl.) */ stack--; size = - *addr; addr += size - 1 - DEBUGWORDS; *addr++ = (long) curOper; for (i=0; i < DEBUGWORDS-1; i++) *addr++ = *stack++; } #else #define whocalledme(addr, stack) #endif /* :h2.xiFree() - User-Callable "Return Memory" Routine The actual beginning of the block is one 'long' before the address we gave to the user. The block begins and ends with '-size' in words. */ void xiFree(long *addr) /* user's memory to be returned */ { register long size; /* amount of memory in this block */ register struct freeblock *p; /* identical to 'addr' */ if (addr == NULL) { /* common "mistake", so allow it (CHT) */ printf("\nxiFree(NULL)?\n"); return; } size = *--addr; /* Make sure this address looks OK; 'size' must be less than zero (meaning the block is allocated) and should be repeated at the end of the block. */ if (size >= 0) Abort("free: bad size"); if (addr[-1 - size] != size) Abort("free: mismatched size"); /* Now make this a 'freeblock' structure and tack it on the FRONT of the free list (where uncombined blocks go): */ AvailableWords -= size; /* actually INCREASES AvailableWords */ p = (struct freeblock *) addr; p->back = &firstfree; (p->fore = firstfree.fore)->back = p; firstfree.fore = p; /* If we have too many uncombined blocks, call combine() to combine one. */ if (++uncombined > MAXUNCOMBINED) { combine(); if (mallocdebug) { printf("xiFree(%p) with combine, ", (void *)addr); dumpchain(); } } else { if (mallocdebug) { printf("xiFree(%p), ", (void *)addr); dumpchain(); } } return; } /* :h3.combine() - Subroutine of xiFree() to Combine Blocks This routine tries to combine the block just before 'firstcombined'. In any event, that block will be moved to the end of the list (after 'firstcombined'). */ static void combine(void) { register struct freeblock *p; /* block we will try to combine */ register long *addr; /* identical to 'p' for 'long' access */ register long size; /* size of this block */ register long size2; /* size of potential combinee */ p = firstcombined->back; if (p == &firstfree) Abort("why are we combining?"); addr = (long *) p; size = - p->size; if (--uncombined < 0) Abort("too many combine()s"); if (addr[-1] < 0 && addr[size] < 0) { /* We special case the situation where no combining can be done. Then, we just mark the chain "combined" (i.e., positive size), move the 'firstcombined' pointer back in the chain, and return. */ addr[0] = addr[size - 1] = size; firstcombined = (struct freeblock *) addr; return; } /* Otherwise, we unhook this pointer from the chain: */ unhook(p); /* First we attempt to combine this with the block immediately above: */ size2 = addr[-1]; if (size2 > 0) { /* i.e., block above is free */ *addr = COMBINED; /* might help debug */ addr -= size2; if (addr[0] != size2) Abort("bad block above"); unhook((struct freeblock *)addr); size += size2; } /* At this point 'addr' and 'size' may be the original block, or it may be the newly combined block. Now we attempt to combine it with the block below: */ p = (struct freeblock *) (addr + size); size2 = p->size; if (size2 > 0) { /* i.e., block below is free */ p->size = COMBINED; if (size2 != ((long *) p)[size2 - 1]) Abort("bad block below"); unhook(p); size += size2; } /* Finally we take the newly combined block and put it on the end of the chain by calling the "freeuncombinable" subroutine: */ freeuncombinable(addr, size); } /* :h3.freeuncombinable() - Free a Block That Need Not be Combined This block is "uncombinable" either because we have already combined it with its eligible neighbors, or perhaps because we know it has no neighbors. */ static void freeuncombinable(long *addr, /* address of the block to be freed */ long size) /* size of block in words */ { register struct freeblock *p; /* a convenient synonym for 'addr' */ /* Mark block allocated and combined by setting its 'size' positive: */ addr[size - 1] = addr[0] = size; /* Now tack the block on the end of the doubly-linked free list: */ p = (struct freeblock *) addr; p->fore = &lastfree; (p->back = lastfree.back)->fore = p; lastfree.back = p; /* If we have previously had no combined blocks, we must update 'firstcombined' to point to this block: */ if (firstcombined->fore == NULL) firstcombined = p; } /* :h3.unhook() - Unhook a Block from the Doubly-linked List The only tricky thing here is to make sure that 'firstcombined' is updated if this block happened to be the old 'firstcombined'. (We would never be unhooking 'firstfree' or 'lastfree', so we do not have to worry about the end cases.) */ static void unhook(struct freeblock *p) /* block to unhook */ { p->back->fore = p->fore; p->fore->back = p->back; if (firstcombined == p) firstcombined = p->fore; } /* :h2.xiMalloc() - Main User Entry Point for Getting Memory We have two slightly different versions of xiMalloc(). In the case where we have TYPE1IMAGER and a font cache, we are prepared, when nominally out of memory, to loop calling TYPE1IMAGER's GimeSpace() to release font cache. */ /* The following code put in by MDC on 11/10/90 */ #ifdef TYPE1IMAGER static char *malloc_local(unsigned size); char * xiMalloc(unsigned size) { char *memaddr; while ( (memaddr = malloc_local(size)) == NULL ) { /* Ask TYPE1IMAGER to give us some of its cache back */ if ( I_GimeSpace() == 0 ) break; /* We are really, really, out of memory */ } return(memaddr); } #endif /* Now begins the real workhorse xiMalloc() (called 'malloc_local' if we are taking advantage of TYPE1IMAGER). Its argument is an unsigned; at least that lets users with 16-bit integers get a 64K chunk of memory, and it is also compatible with the definition of a "size_t" in most systems. */ #ifdef TYPE1IMAGER static char * malloc_local(unsigned Size) /* number of bytes the user requested */ #else char * xiMalloc(unsigned Size) #endif { register long size = (long)Size; /* a working register for size */ register struct freeblock *p; /* tentative block to be returned */ register long excess; /* words in excess of user request */ register long *area; /* a convenient synonym for 'p' */ /* First, we increase 'size' to allow for the two size fields we will save with the block, plus any information for debug purposes. Then we ensure that the block will be large enough to hold our 'freeblock' information. Finally we convert it to be in words (longs), not bytes, increased to span an integral number of double words, so that all memory blocks dispensed with be properly aligned. */ size += 2*sizeof(long) + DEBUGWORDS*sizeof(long); if (size < sizeof(struct freeblock) + sizeof(long)) size = sizeof(struct freeblock) + sizeof(long); size = ((unsigned) (size + sizeof(double) - 1) / sizeof(double)) * (sizeof(double)/sizeof(long)); /* For speed, we will try first to give the user back a very recently returned block--one that is on the front of the chain before 'firstcombined'. These blocks still have negative sizes, and need only to be "unhook"ed: */ size = -size; for (p=firstfree.fore; p != firstcombined; p=p->fore) { if (p->size == size) { unhook(p); uncombined--; if (mallocdebug) { printf("fast xiMalloc(%ld) = %p, ", size, (void *)p); dumpchain(); } AvailableWords += size; /* decreases AvailableWords */ whocalledme(p, &Size); return((char *)&p->fore); } } /* Well, if we get here, there are no uncombined blocks matching the user's request. So, we search the rest of the chain for a block that is big enough. ('size' becomes positive again): */ size = -size; for (;; p = p->fore) { /* If we hit the end of the chain (p->size == 0), we are probably out of memory. However, we should first try to combine any memory that has not yet been combined before we give that pessimistic answer. If we succeed in combining, we can call ourselves recursively to try to allocate the requested amount: */ if (p->size == 0) { if (uncombined <= 0) return(NULL); while (firstfree.fore != firstcombined) combine(); return(xiMalloc(sizeof(long) * (size - 2 - DEBUGWORDS))); } /* Otherwise, we keep searching until we find a big enough block: */ if (p->size >= size) break; } /* At this point, 'p' contains a block at least as big as what the user requested, so we take it off the free chain. If it is excessively big, we return the excess to the free chain: */ unhook(p); excess = p->size - size; area = (long *) p; if (excess > MINEXCESS) freeuncombinable(area + size, excess); else size = p->size; AvailableWords -= size; /* Mark first and last word of block with the negative of the size, to flag that this block is allocated: */ area[size - 1] = area[0] = - size; if (mallocdebug) { printf("slow xiMalloc(%ld) @ %p, ", size, (void *)area); dumpchain(); } whocalledme(area, &Size); /* The address we return to the user is one 'long' BELOW the address of the block. This protects our 'size' field, so we can tell the size of the block when he returns it to us with xiFree(). Also, he better not touch the 'size' field at the end of the block either. (That would be nasty of him, as he would be touching memory outside of the bytes he requested). */ return((char *) (area + 1)); } /* :h2 id=addmem.addmemory() - Initialize Free Memory This routine should be called at initialization to initialize the free chain. There is no standard way to do this in C. We want the memory dispensed by malloc to be aligned on a double word boundary (because some machines either require alignment, or are more efficient if accesses are aligned). Since the total size of any block created by malloc is an integral number of double words, all we have to do to ensure alignment is to adjust each large block added to the free chain to start on an odd long-word boundary. (Malloc's size field will occupy the odd long and the user's memory will then begin on an even boundary.) Since we fill in additional size fields at the beginning and end of each of the large freeblocks, we need only adjust the address passed to addmemory to a double word boundary. */ #define MAXAREAS 10 /* there can be this many calls to addmemory() */ static long *freearea[MAXAREAS] = { NULL }; /* so we can report later */ void addmemory(long *addr, /* beginning of free area */ long size) /* number of bytes of free area */ { register int i; /* loop index variable */ register long *aaddr; /* aligned beginning of free area */ #if DEBUGWORDS printf("malloc has DEBUGWORDS=%d\n", DEBUGWORDS); #endif /* First link together firstfree and lastfree if necessary: */ if (firstfree.fore == NULL) { firstfree.fore = &lastfree; lastfree.back = &firstfree; } /* We'll record where the area was that was given to us for later reports: */ for (i=0; i < MAXAREAS; i++) if (freearea[i] == NULL) break; if (i >= MAXAREAS) Abort("too many addmemory()s"); aaddr = (long *) ( ((long) addr + sizeof(double) - 1) & - (long)sizeof(double) ); size -= (char *) aaddr - (char *) addr; freearea[i] = aaddr; /* Convert 'size' to number of longs, and store '-size' guards at the beginning and end of this area so we will not accidentally recombine the first or last block: */ size /= sizeof(long); AvailableWords += size - 2; aaddr[size - 1] = aaddr[0] = -size; /* Finally, call 'freeuncombinable' to put the remaining memory on the free list: */ freeuncombinable(aaddr + 1, size - 2); } /* :h3.delmemory() - Delete Memory Pool */ void delmemory(void) { register int i; AvailableWords = 0; firstfree.fore = &lastfree; lastfree.back = &firstfree; firstcombined = &lastfree; uncombined = 0; for (i=0; ifore) { if (--i < 0) Abort("too many uncombined areas"); size = p->size; printf(". . . area @ %p, size = %ld\n", (void *)p, -size); if (size >= 0 || size != ((int *) p)[-1 - size]) Abort("dumpchain: bad size"); if (p->back != back) Abort("dumpchain: bad back"); back = p; } printf("DUMPING COMBINED FREE LIST:\n"); for (; p != &lastfree; p = p->fore) { size = p->size; printf(". . . area @ %p, size = %ld\n", (void *)p, size); if (size <= 0 || size != ((int *) p)[size - 1]) Abort("dumpchain: bad size"); if (p->back != back) Abort("dumpchain: bad back"); back = p; } if (back != lastfree.back) Abort("dumpchain: bad lastfree"); } #ifdef notused /* :h3.reportarea() - Display a Contiguous Set of Memory Blocks */ static void reportarea(long *area) /* start of blocks (from addmemory) */ { register long size; /* size of current block */ register long wholesize; /* size of original area */ register struct freeblock *p; /* pointer to block */ if (area == NULL) return; wholesize = - *area++; wholesize -= 2; while (wholesize > 0) { size = *area; if (size < 0) { register int i,j; size = -size; printf("Allocated %5ld bytes at %p, first words=%08lx %08lx\n", size * sizeof(long), area + 1, area[1], area[2]); #if DEBUGWORDS printf(" ...Last operator: %s\n", (char *)area[size-DEBUGWORDS-1]); #endif for (i = size - DEBUGWORDS; i < size - 2; i += 8) { printf(" ..."); for (j=0; j<8; j++) printf(" %08lx", area[i+j]); printf("\n"); } } else { printf("Free %ld bytes at %p\n", size * sizeof(long), area); if (size == 0) Abort("zero sized memory block"); for (p = firstfree.fore; p != NULL; p = p->fore) if ((long *) p == area) break; if ((long *) p != area) Abort("not found on forward chain"); for (p = lastfree.back; p != NULL; p = p->back) if ((long *) p == area) break; if ((long *) p != area) Abort("not found on backward chain"); } if (area[0] != area[size - 1]) Abort("unmatched check sizes"); area += size; wholesize -= size; } } /* :h3.MemReport() - Display All of Memory */ void MemReport(void) { register int i; dumpchain(); for (i=0; i