fis-gtm/sr_port/mcalloc.c

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/****************************************************************
* *
* Copyright 2001, 2011 Fidelity Information Services, Inc *
* *
* This source code contains the intellectual property *
* of its copyright holder(s), and is made available *
* under a license. If you do not know the terms of *
* the license, please stop and do not read further. *
* *
****************************************************************/
#include "mdef.h"
#include "gtm_string.h"
#include "mmemory.h"
#include "min_max.h"
GBLREF int mcavail;
GBLREF mcalloc_hdr *mcavailptr, *mcavailbase;
char *mcalloc(unsigned int n)
{
mcalloc_hdr *hdr, *nxt, *ptr;
int new_size, rel_size;
/* Choice of char_ptr_t made because it is a 64 bit pointer on Tru64 which
* is the alignment we need there, or any other 64 bit platforms we support
* in the future.
*/
n = ROUND_UP2(n, SIZEOF(char_ptr_t));
if (n > mcavail)
{ /* No sufficient space in the current block. Follow the link and check if the next block has sufficient
* space. There is no next block or the next one doesn't have enough space, allocate a new block with
* the requested size and insert it after the current block.
*/
hdr = mcavailptr->link;
if (NULL == hdr || n > hdr->size)
{
if (NULL != hdr)
{ /* i.e. the next block doesn't have sufficient space for n. Release as many small blocks as
* necessary to make up for the space that we are allocating for the large block.
* By release several small blocks and replacing them with a large block ensures that total
* memory footprint is not increased due to a rare occurence of large routine compilation.
*/
rel_size = 0;
for (nxt = hdr; NULL != nxt && (rel_size += nxt->size) < n; nxt = ptr)
{
ptr = nxt->link;
free(nxt);
}
} else
nxt = NULL;
new_size = (int)MAX(MC_DSBLKSIZE, (n + MCALLOC_HDR_SZ));
hdr = (mcalloc_hdr *)malloc(new_size);
hdr->link = nxt;
hdr->size = (int4)(new_size - MCALLOC_HDR_SZ);
mcavailptr->link = hdr;
}
assert(n <= hdr->size);
memset(&hdr->data[0], 0, hdr->size);
mcavailptr = hdr;
mcavail = hdr->size;
}
mcavail -= n;
assert(mcavail >= 0);
return &mcavailptr->data[mcavail];
}