X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=mmalloc%2Fmmalloc.c;fp=mmalloc%2Fmmalloc.c;h=7c60fe2d57b95bbc9ea8751e8d1df7399800058f;hb=d70485fb7a2776fbfeccdabc568aa98ab3a80225;hp=0000000000000000000000000000000000000000;hpb=70ed84c05dfe890425592cc207f7a866f0afb04e;p=ocaml-ancient.git diff --git a/mmalloc/mmalloc.c b/mmalloc/mmalloc.c new file mode 100644 index 0000000..7c60fe2 --- /dev/null +++ b/mmalloc/mmalloc.c @@ -0,0 +1,337 @@ +/* Memory allocator `malloc'. + Copyright 1990, 1991, 1992 Free Software Foundation + + Written May 1989 by Mike Haertel. + Heavily modified Mar 1992 by Fred Fish for mmap'd version. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +Boston, MA 02111-1307, USA. + + The author may be reached (Email) at the address mike@ai.mit.edu, + or (US mail) as Mike Haertel c/o Free Software Foundation. */ + +#include /* Prototypes for memcpy, memmove, memset, etc */ + +#include "mmprivate.h" + +/* Prototypes for local functions */ + +static int initialize PARAMS ((struct mdesc *)); +static PTR morecore PARAMS ((struct mdesc *, size_t)); +static PTR align PARAMS ((struct mdesc *, size_t)); + +/* Aligned allocation. */ + +static PTR +align (mdp, size) + struct mdesc *mdp; + size_t size; +{ + PTR result; + unsigned long int adj; + + result = mdp -> morecore (mdp, size); + adj = RESIDUAL (result, BLOCKSIZE); + if (adj != 0) + { + adj = BLOCKSIZE - adj; + mdp -> morecore (mdp, adj); + result = (char *) result + adj; + } + return (result); +} + +/* Set everything up and remember that we have. */ + +static int +initialize (mdp) + struct mdesc *mdp; +{ + mdp -> heapsize = HEAP / BLOCKSIZE; + mdp -> heapinfo = (malloc_info *) + align (mdp, mdp -> heapsize * sizeof (malloc_info)); + if (mdp -> heapinfo == NULL) + { + return (0); + } + memset ((PTR)mdp -> heapinfo, 0, mdp -> heapsize * sizeof (malloc_info)); + mdp -> heapinfo[0].free.size = 0; + mdp -> heapinfo[0].free.next = mdp -> heapinfo[0].free.prev = 0; + mdp -> heapindex = 0; + mdp -> heapbase = (char *) mdp -> heapinfo; + mdp -> flags |= MMALLOC_INITIALIZED; + return (1); +} + +/* Get neatly aligned memory, initializing or + growing the heap info table as necessary. */ + +static PTR +morecore (mdp, size) + struct mdesc *mdp; + size_t size; +{ + PTR result; + malloc_info *newinfo, *oldinfo; + size_t newsize; + + result = align (mdp, size); + if (result == NULL) + { + return (NULL); + } + + /* Check if we need to grow the info table. */ + if ((size_t) BLOCK ((char *) result + size) > mdp -> heapsize) + { + newsize = mdp -> heapsize; + while ((size_t) BLOCK ((char *) result + size) > newsize) + { + newsize *= 2; + } + newinfo = (malloc_info *) align (mdp, newsize * sizeof (malloc_info)); + if (newinfo == NULL) + { + mdp -> morecore (mdp, -size); + return (NULL); + } + memset ((PTR) newinfo, 0, newsize * sizeof (malloc_info)); + memcpy ((PTR) newinfo, (PTR) mdp -> heapinfo, + mdp -> heapsize * sizeof (malloc_info)); + oldinfo = mdp -> heapinfo; + newinfo[BLOCK (oldinfo)].busy.type = 0; + newinfo[BLOCK (oldinfo)].busy.info.size + = BLOCKIFY (mdp -> heapsize * sizeof (malloc_info)); + mdp -> heapinfo = newinfo; + __mmalloc_free (mdp, (PTR)oldinfo); + mdp -> heapsize = newsize; + } + + mdp -> heaplimit = BLOCK ((char *) result + size); + return (result); +} + +/* Allocate memory from the heap. */ + +PTR +mmalloc (md, size) + PTR md; + size_t size; +{ + struct mdesc *mdp; + PTR result; + size_t block, blocks, lastblocks, start; + register size_t i; + struct list *next; + register size_t log; + + if (size == 0) + { + return (NULL); + } + + mdp = MD_TO_MDP (md); + + if (mdp -> mmalloc_hook != NULL) + { + return ((*mdp -> mmalloc_hook) (md, size)); + } + + if (!(mdp -> flags & MMALLOC_INITIALIZED)) + { + if (!initialize (mdp)) + { + return (NULL); + } + } + + if (size < sizeof (struct list)) + { + size = sizeof (struct list); + } + + /* Determine the allocation policy based on the request size. */ + if (size <= BLOCKSIZE / 2) + { + /* Small allocation to receive a fragment of a block. + Determine the logarithm to base two of the fragment size. */ + log = 1; + --size; + while ((size /= 2) != 0) + { + ++log; + } + + /* Look in the fragment lists for a + free fragment of the desired size. */ + next = mdp -> fraghead[log].next; + if (next != NULL) + { + /* There are free fragments of this size. + Pop a fragment out of the fragment list and return it. + Update the block's nfree and first counters. */ + result = (PTR) next; + next -> prev -> next = next -> next; + if (next -> next != NULL) + { + next -> next -> prev = next -> prev; + } + block = BLOCK (result); + if (--mdp -> heapinfo[block].busy.info.frag.nfree != 0) + { + mdp -> heapinfo[block].busy.info.frag.first = + RESIDUAL (next -> next, BLOCKSIZE) >> log; + } + + /* Update the statistics. */ + mdp -> heapstats.chunks_used++; + mdp -> heapstats.bytes_used += 1 << log; + mdp -> heapstats.chunks_free--; + mdp -> heapstats.bytes_free -= 1 << log; + } + else + { + /* No free fragments of the desired size, so get a new block + and break it into fragments, returning the first. */ + result = mmalloc (md, BLOCKSIZE); + if (result == NULL) + { + return (NULL); + } + + /* Link all fragments but the first into the free list. */ + for (i = 1; i < (size_t) (BLOCKSIZE >> log); ++i) + { + next = (struct list *) ((char *) result + (i << log)); + next -> next = mdp -> fraghead[log].next; + next -> prev = &mdp -> fraghead[log]; + next -> prev -> next = next; + if (next -> next != NULL) + { + next -> next -> prev = next; + } + } + + /* Initialize the nfree and first counters for this block. */ + block = BLOCK (result); + mdp -> heapinfo[block].busy.type = log; + mdp -> heapinfo[block].busy.info.frag.nfree = i - 1; + mdp -> heapinfo[block].busy.info.frag.first = i - 1; + + mdp -> heapstats.chunks_free += (BLOCKSIZE >> log) - 1; + mdp -> heapstats.bytes_free += BLOCKSIZE - (1 << log); + mdp -> heapstats.bytes_used -= BLOCKSIZE - (1 << log); + } + } + else + { + /* Large allocation to receive one or more blocks. + Search the free list in a circle starting at the last place visited. + If we loop completely around without finding a large enough + space we will have to get more memory from the system. */ + blocks = BLOCKIFY(size); + start = block = MALLOC_SEARCH_START; + while (mdp -> heapinfo[block].free.size < blocks) + { + block = mdp -> heapinfo[block].free.next; + if (block == start) + { + /* Need to get more from the system. Check to see if + the new core will be contiguous with the final free + block; if so we don't need to get as much. */ + block = mdp -> heapinfo[0].free.prev; + lastblocks = mdp -> heapinfo[block].free.size; + if (mdp -> heaplimit != 0 && + block + lastblocks == mdp -> heaplimit && + mdp -> morecore (mdp, 0) == ADDRESS(block + lastblocks) && + (morecore (mdp, (blocks - lastblocks) * BLOCKSIZE)) != NULL) + { + /* Which block we are extending (the `final free + block' referred to above) might have changed, if + it got combined with a freed info table. */ + block = mdp -> heapinfo[0].free.prev; + + mdp -> heapinfo[block].free.size += (blocks - lastblocks); + mdp -> heapstats.bytes_free += + (blocks - lastblocks) * BLOCKSIZE; + continue; + } + result = morecore(mdp, blocks * BLOCKSIZE); + if (result == NULL) + { + return (NULL); + } + block = BLOCK (result); + mdp -> heapinfo[block].busy.type = 0; + mdp -> heapinfo[block].busy.info.size = blocks; + mdp -> heapstats.chunks_used++; + mdp -> heapstats.bytes_used += blocks * BLOCKSIZE; + return (result); + } + } + + /* At this point we have found a suitable free list entry. + Figure out how to remove what we need from the list. */ + result = ADDRESS(block); + if (mdp -> heapinfo[block].free.size > blocks) + { + /* The block we found has a bit left over, + so relink the tail end back into the free list. */ + mdp -> heapinfo[block + blocks].free.size + = mdp -> heapinfo[block].free.size - blocks; + mdp -> heapinfo[block + blocks].free.next + = mdp -> heapinfo[block].free.next; + mdp -> heapinfo[block + blocks].free.prev + = mdp -> heapinfo[block].free.prev; + mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next + = mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev + = mdp -> heapindex = block + blocks; + } + else + { + /* The block exactly matches our requirements, + so just remove it from the list. */ + mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev + = mdp -> heapinfo[block].free.prev; + mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next + = mdp -> heapindex = mdp -> heapinfo[block].free.next; + mdp -> heapstats.chunks_free--; + } + + mdp -> heapinfo[block].busy.type = 0; + mdp -> heapinfo[block].busy.info.size = blocks; + mdp -> heapstats.chunks_used++; + mdp -> heapstats.bytes_used += blocks * BLOCKSIZE; + mdp -> heapstats.bytes_free -= blocks * BLOCKSIZE; + } + + return (result); +} + +/* When using this package, provide a version of malloc/realloc/free built + on top of it, so that if we use the default sbrk() region we will not + collide with another malloc package trying to do the same thing, if + the application contains any "hidden" calls to malloc/realloc/free (such + as inside a system library). */ + +PTR +malloc (size) + size_t size; +{ + PTR result; + + result = mmalloc ((PTR) NULL, size); + return (result); +}