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+/* table.h - definitions for tables for keeping track of allocated memory */
+
+/* Copyright (C) 2001-2003 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash, the Bourne-Again SHell.
+
+ Bash is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ Bash 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _MTABLE_H
+#define _MTABLE_H
+
+#include "imalloc.h"
+
+#ifdef MALLOC_REGISTER
+
+/* values for flags byte. */
+#define MT_ALLOC 0x01
+#define MT_FREE 0x02
+
+/*
+ * Memory table entry.
+ *
+ * MEM is the address of the allocated pointer.
+ * SIZE is the requested allocation size.
+ * FLAGS includes either MT_ALLOC (MEM is allocated) or MT_FREE (MEM is
+ * not allocated). Other flags later.
+ * FUNC is set to the name of the function doing the allocation (from the
+ * `tag' argument to register_alloc().
+ * FILE and LINE are the filename and line number of the last allocation
+ * and free (depending on STATUS) of MEM.
+ * NALLOC and NFREE are incremented on each allocation that returns MEM or
+ * each free of MEM, respectively (way to keep track of memory reuse
+ * and how well the free lists are working).
+ *
+ */
+typedef struct mr_table {
+ PTR_T mem;
+ size_t size;
+ char flags;
+ const char *func;
+ const char *file;
+ int line;
+ int nalloc, nfree;
+} mr_table_t;
+
+#define REG_TABLE_SIZE 8192
+
+extern mr_table_t *mr_table_entry __P((PTR_T));
+extern void mregister_alloc __P((const char *, PTR_T, size_t, const char *, int));
+extern void mregister_free __P((PTR_T, int, const char *, int));
+extern void mregister_describe_mem ();
+extern void mregister_dump_table __P((void));
+extern void mregister_table_init __P((void));
+
+/* NOTE: HASH_MIX taken from dmalloc (http://dmalloc.com) */
+
+/*
+ * void HASH_MIX
+ *
+ * DESCRIPTION:
+ *
+ * Mix 3 32-bit values reversibly. For every delta with one or two
+ * bits set, and the deltas of all three high bits or all three low
+ * bits, whether the original value of a,b,c is almost all zero or is
+ * uniformly distributed.
+ *
+ * If HASH_MIX() is run forward or backward, at least 32 bits in a,b,c
+ * have at least 1/4 probability of changing. If mix() is run
+ * forward, every bit of c will change between 1/3 and 2/3 of the
+ * time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
+ *
+ * HASH_MIX() takes 36 machine instructions, but only 18 cycles on a
+ * superscalar machine (like a Pentium or a Sparc). No faster mixer
+ * seems to work, that's the result of my brute-force search. There
+ * were about 2^68 hashes to choose from. I only tested about a
+ * billion of those.
+ */
+#define HASH_MIX(a, b, c) \
+ do { \
+ a -= b; a -= c; a ^= (c >> 13); \
+ b -= c; b -= a; b ^= (a << 8); \
+ c -= a; c -= b; c ^= (b >> 13); \
+ a -= b; a -= c; a ^= (c >> 12); \
+ b -= c; b -= a; b ^= (a << 16); \
+ c -= a; c -= b; c ^= (b >> 5); \
+ a -= b; a -= c; a ^= (c >> 3); \
+ b -= c; b -= a; b ^= (a << 10); \
+ c -= a; c -= b; c ^= (b >> 15); \
+ } while(0)
+
+#endif /* MALLOC_REGISTER */
+
+#endif /* _MTABLE_H */