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88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
/* Defines a buffered memory allocation abstraction that reduces calls to
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malloc.
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Copyright (C) 1989-1998 Free Software Foundation, Inc.
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written by Douglas C. Schmidt (schmidt@ics.uci.edu)
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This file is part of GNU GPERF.
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GNU GPERF is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 1, or (at your option)
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any later version.
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GNU GPERF is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU GPERF; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
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#include "config.h"
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#include <stdio.h>
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#include <stdlib.h> /* declares malloc(), exit() */
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#include "trace.h"
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/* Determine default alignment. If your C++ compiler does not
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like this then try something like #define DEFAULT_ALIGNMENT 8. */
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struct fooalign {char x; double d;};
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const int ALIGNMENT = ((char *)&((struct fooalign *) 0)->d - (char *)0);
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/* Provide an abstraction that cuts down on the number of
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calls to NEW by buffering the memory pool from which
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strings are allocated. */
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void *
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operator new (size_t size)
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{
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T (Trace t ("operator new");)
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static char *buf_start = 0; /* Large array used to reduce calls to NEW. */
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static char *buf_end = 0; /* Indicates end of BUF_START. */
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static size_t buf_size = 4096; /* Size of buffer pointed to by BUF_START. */
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char *temp;
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/* Align this on correct boundaries, just to be safe... */
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size = ((size + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
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/* If we are about to overflow our buffer we'll just grab another
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chunk of memory. Since we never free the original memory it
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doesn't matter that no one points to the beginning of that
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chunk. Note we use a heuristic that grows the buffer either by
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size of the request or by twice the previous size, whichever is
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larger. */
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if (buf_start + size >= buf_end)
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{
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buf_size *= 2;
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if (buf_size < size)
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buf_size = size;
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if ((buf_start = (char *)malloc (buf_size)) != (char *)0)
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buf_end = buf_start + buf_size;
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else
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{
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fprintf (stderr, "Virtual memory exhausted in `operator new'\n");
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exit (1);
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}
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}
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temp = buf_start;
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buf_start += size;
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return temp;
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}
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/* We need this deletion operator in order to make the linker happy.
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Because `operator new' and `operator delete' always come together. */
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void
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operator delete (void *ptr)
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#ifdef HAVE_THROW_DECL
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throw()
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#endif
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{
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T (Trace t ("operator delete");)
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// We cannot call free here, as it doesn't match the mallocs.
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// free ((char *) ptr);
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(void) ptr;
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}
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