Initial revision

1 files changed, 456 insertions, 0 deletions

diff --git a/generic/tclAlloc.c b/generic/tclAlloc.c
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index 0000000..cf07036
--- /dev/null
+++ b/generic/tclAlloc.c
@@ -0,0 +1,456 @@
+/* 
+ * tclAlloc.c --
+ *
+ *	This is a very fast storage allocator.  It allocates blocks of a
+ *	small number of different sizes, and keeps free lists of each size.
+ *	Blocks that don't exactly fit are passed up to the next larger size.
+ *	Blocks over a certain size are directly allocated from the system.
+ *
+ * Copyright (c) 1983 Regents of the University of California.
+ * Copyright (c) 1996-1997 Sun Microsystems, Inc.
+ *
+ * Portions contributed by Chris Kingsley, Jack Jansen and Ray Johnson.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) tclAlloc.c 1.4 97/08/11 18:45:38
+ */
+
+#include "tclInt.h"
+#include "tclPort.h"
+
+#ifdef TCL_DEBUG
+#   define DEBUG
+/* #define MSTATS */
+#   define RCHECK
+#endif
+
+typedef unsigned long caddr_t;
+
+/*
+ * The overhead on a block is at least 4 bytes.  When free, this space
+ * contains a pointer to the next free block, and the bottom two bits must
+ * be zero.  When in use, the first byte is set to MAGIC, and the second
+ * byte is the size index.  The remaining bytes are for alignment.
+ * If range checking is enabled then a second word holds the size of the
+ * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
+ * The order of elements is critical: ov_magic must overlay the low order
+ * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
+ */
+
+union overhead {
+    union overhead *ov_next;	/* when free */
+    struct {
+	unsigned char	ovu_magic0;	/* magic number */
+	unsigned char	ovu_index;	/* bucket # */
+	unsigned char	ovu_unused;	/* unused */
+	unsigned char	ovu_magic1;	/* other magic number */
+#ifdef RCHECK
+	unsigned short	ovu_rmagic;	/* range magic number */
+	unsigned long	ovu_size;	/* actual block size */
+#endif
+    } ovu;
+#define ov_magic0	ovu.ovu_magic0
+#define ov_magic1	ovu.ovu_magic1
+#define ov_index	ovu.ovu_index
+#define ov_rmagic	ovu.ovu_rmagic
+#define ov_size	ovu.ovu_size
+};
+
+
+#define MAGIC		0xef		/* magic # on accounting info */
+#define RMAGIC		0x5555		/* magic # on range info */
+
+#ifdef RCHECK
+#define	RSLOP		sizeof (unsigned short)
+#else
+#define	RSLOP		0
+#endif
+
+#define OVERHEAD (sizeof(union overhead) + RSLOP)
+
+/*
+ * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
+ * smallest allocatable block is 8 bytes.  The overhead information
+ * precedes the data area returned to the user.
+ */
+
+#define NBUCKETS	13
+#define MAXMALLOC	(1<<(NBUCKETS+2))
+static	union overhead *nextf[NBUCKETS];
+
+#ifdef MSTATS
+
+/*
+ * nmalloc[i] is the difference between the number of mallocs and frees
+ * for a given block size.
+ */
+
+static	unsigned int nmalloc[NBUCKETS+1];
+#include <stdio.h>
+#endif
+
+#if defined(DEBUG) || defined(RCHECK)
+#define	ASSERT(p)   if (!(p)) panic(# p)
+#define RANGE_ASSERT(p) if (!(p)) panic(# p)
+#else
+#define	ASSERT(p)
+#define RANGE_ASSERT(p)
+#endif
+
+/*
+ * Prototypes for functions used only in this file.
+ */
+
+static void 		MoreCore _ANSI_ARGS_((int bucket));
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpAlloc --
+ *
+ *	Allocate more memory.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+TclpAlloc(
+    unsigned int nbytes)	/* Number of bytes to allocate. */
+{
+    register union overhead *op;
+    register long bucket;
+    register unsigned amt;
+
+    /*
+     * First the simple case: we simple allocate big blocks directly
+     */
+    if (nbytes + OVERHEAD >= MAXMALLOC) {
+	op = (union overhead *)TclpSysAlloc(nbytes+OVERHEAD, 0);
+	if (op == NULL) {
+	    return NULL;
+	}
+	op->ov_magic0 = op->ov_magic1 = MAGIC;
+	op->ov_index = 0xff;
+#ifdef MSTATS
+	nmalloc[NBUCKETS]++;
+#endif
+#ifdef RCHECK
+	/*
+	 * Record allocated size of block and
+	 * bound space with magic numbers.
+	 */
+	op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
+	op->ov_rmagic = RMAGIC;
+	*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
+#endif
+	return (void *)(op+1);
+    }
+    /*
+     * Convert amount of memory requested into closest block size
+     * stored in hash buckets which satisfies request.
+     * Account for space used per block for accounting.
+     */
+#ifndef RCHECK
+    amt = 8;	/* size of first bucket */
+    bucket = 0;
+#else
+    amt = 16;	/* size of first bucket */
+    bucket = 1;
+#endif
+    while (nbytes + OVERHEAD > amt) {
+	amt <<= 1;
+	if (amt == 0) {
+	    return (NULL);
+	}
+	bucket++;
+    }
+    ASSERT( bucket < NBUCKETS );
+
+    /*
+     * If nothing in hash bucket right now,
+     * request more memory from the system.
+     */
+    if ((op = nextf[bucket]) == NULL) {
+	MoreCore(bucket);
+	if ((op = nextf[bucket]) == NULL) {
+	    return (NULL);
+	}
+    }
+    /*
+     * Remove from linked list
+     */
+    nextf[bucket] = op->ov_next;
+    op->ov_magic0 = op->ov_magic1 = MAGIC;
+    op->ov_index = (unsigned char) bucket;
+#ifdef MSTATS
+    nmalloc[bucket]++;
+#endif
+#ifdef RCHECK
+    /*
+     * Record allocated size of block and
+     * bound space with magic numbers.
+     */
+    op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
+    op->ov_rmagic = RMAGIC;
+    *(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
+#endif
+    return ((char *)(op + 1));
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * MoreCore --
+ *
+ *	Allocate more memory to the indicated bucket.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Attempts to get more memory from the system.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+MoreCore(
+    int bucket)		/* What bucket to allocat to. */
+{
+    register union overhead *op;
+    register long sz;		/* size of desired block */
+    long amt;			/* amount to allocate */
+    int nblks;			/* how many blocks we get */
+
+    /*
+     * sbrk_size <= 0 only for big, FLUFFY, requests (about
+     * 2^30 bytes on a VAX, I think) or for a negative arg.
+     */
+    sz = 1 << (bucket + 3);
+    ASSERT(sz > 0);
+
+    amt = MAXMALLOC;
+    nblks = amt / sz;
+    ASSERT(nblks*sz == amt);
+
+    op = (union overhead *)TclpSysAlloc(amt, 1);
+    /* no more room! */
+    if (op == NULL) {
+	return;
+    }
+    
+    /*
+     * Add new memory allocated to that on
+     * free list for this hash bucket.
+     */
+    nextf[bucket] = op;
+    while (--nblks > 0) {
+	op->ov_next = (union overhead *)((caddr_t)op + sz);
+	op = (union overhead *)((caddr_t)op + sz);
+    }
+    op->ov_next = (union overhead *)NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpFree --
+ *
+ *	Free memory.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclpFree(
+    char *cp)		/* Pointer to memory to free. */
+{   
+    register long size;
+    register union overhead *op;
+
+    if (cp == NULL) {
+	return;
+    }
+
+    op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
+
+    ASSERT(op->ov_magic0 == MAGIC);		/* make sure it was in use */
+    ASSERT(op->ov_magic1 == MAGIC);
+    if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
+	return;
+    }
+
+    RANGE_ASSERT(op->ov_rmagic == RMAGIC);
+    RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
+    size = op->ov_index;
+    if ( size == 0xff ) {
+#ifdef MSTATS
+	nmalloc[NBUCKETS]--;
+#endif
+	TclpSysFree(op);
+	return;
+    }
+    ASSERT(size < NBUCKETS);
+    op->ov_next = nextf[size];	/* also clobbers ov_magic */
+    nextf[size] = op;
+#ifdef MSTATS
+    nmalloc[size]--;
+#endif
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpRealloc --
+ *
+ *	Reallocate memory.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+TclpRealloc(
+    char *cp,			/* Pointer to alloced block. */
+    unsigned int nbytes)	/* New size of memory. */
+{   
+    int i;
+    union overhead *op;
+    int expensive;
+    unsigned long maxsize;
+
+    if (cp == NULL) {
+	return (TclpAlloc(nbytes));
+    }
+
+    op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
+
+    ASSERT(op->ov_magic0 == MAGIC);		/* make sure it was in use */
+    ASSERT(op->ov_magic1 == MAGIC);
+    if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
+	return NULL;
+    }
+
+    RANGE_ASSERT(op->ov_rmagic == RMAGIC);
+    RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
+    i = op->ov_index;
+
+    /*
+     * If the block isn't in a bin, just realloc it.
+     */
+
+    if (i == 0xff) {
+	op = (union overhead *) TclpSysRealloc(op, nbytes+OVERHEAD);
+	if (op == NULL) {
+	    return NULL;
+	}
+#ifdef MSTATS
+	nmalloc[NBUCKETS]++;
+#endif
+#ifdef RCHECK
+	/*
+	 * Record allocated size of block and update magic number bounds.
+	 */
+
+	op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
+	*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
+#endif
+	return (char *)(op+1);
+    }
+    maxsize = 1 << (i+3);
+    expensive = 0;
+    if ( nbytes + OVERHEAD > maxsize ) {
+	expensive = 1;
+    } else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) ) {
+	expensive = 1;
+    }
+
+    if (expensive) {
+	void *newp;
+		
+	newp = TclpAlloc(nbytes);
+	if ( newp == NULL ) {
+	    return NULL;
+	}
+	maxsize -= OVERHEAD;
+	if ( maxsize < nbytes )
+	    nbytes = maxsize;
+	memcpy((VOID *) newp, (VOID *) cp, (size_t) nbytes);
+	TclpFree(cp);
+	return newp;
+    }
+    
+    /*
+     * Ok, we don't have to copy, it fits as-is
+     */
+#ifdef RCHECK
+    op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
+    *(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
+#endif
+    return(cp);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * mstats --
+ *
+ *	Prints two lines of numbers, one showing the length of the 
+ *	free list for each size category, the second showing the 
+ *	number of mallocs - frees for each size category.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+#ifdef MSTATS
+void
+mstats(
+    char *s)	/* Where to write info. */
+{
+    register int i, j;
+    register union overhead *p;
+    int totfree = 0,
+	totused = 0;
+
+    fprintf(stderr, "Memory allocation statistics %s\nTclpFree:\t", s);
+    for (i = 0; i < NBUCKETS; i++) {
+	for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
+	    fprintf(stderr, " %d", j);
+	totfree += j * (1 << (i + 3));
+    }
+    fprintf(stderr, "\nused:\t");
+    for (i = 0; i < NBUCKETS; i++) {
+	fprintf(stderr, " %d", nmalloc[i]);
+	totused += nmalloc[i] * (1 << (i + 3));
+    }
+    fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
+	    totused, totfree);
+    fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", 
+	    MAXMALLOC, nmalloc[NBUCKETS]);
+}
+#endif