/* 
 * tclMacAlloc.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 by calling NewPtr.
 *
 * Copyright (c) 1983 Regents of the University of California.
 * Copyright (c) 1996 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: @(#) tclMacAlloc.c 1.7 96/09/22 15:37:03
 */

#ifdef TCL_DEBUG
#   define DEBUG
/* #define MSTATS */
#   define RCHECK
#endif

typedef unsigned long caddr_t;

#include "tclMacInt.h"
#include <Memory.h>
#include <stdlib.h>
#include <string.h>

/*
 * Flags that are used by ConfigureMemory to define how the allocator
 * should work.  They can be or'd together.
 */
#define MEMORY_ALL_SYS 1	/* All memory should come from the system heap. */

static int memoryFlags = 0;

/*
 * 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 11*/
#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

/*
 * The following typedef and variable are used to keep track of memory
 * blocks that are allocated directly from the System Heap.  This chunks
 * of memory must always be freed - even if we crash.
 */
typedef struct listEl {
    Handle		memoryHandle;
    struct listEl *	next;
} ListEl;

ListEl * systemMemory = NULL;
ListEl * appMemory = NULL;

#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_(());
static void * 		SysAlloc _ANSI_ARGS_((long size, int high));
static void 		SysFree _ANSI_ARGS_((void * ptr));
static pascal void	CleanUpExitProc _ANSI_ARGS_((void));
void 			ConfigureMemory _ANSI_ARGS_((int flags));
void			FreeAllMemory _ANSI_ARGS_((void));

/*
 *----------------------------------------------------------------------
 *
 * TclpAlloc --
 *
 *	Allocate more memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

char *
TclpAlloc(nbytes)
    size_t nbytes;
{
    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 *)SysAlloc(nbytes+OVERHEAD, false);
	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 = 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(bucket)
    int bucket;
{
    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 *)SysAlloc(amt, true);
    /* 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(cp)
    char *cp;
{   
    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
	SysFree((Ptr) 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(cp, nbytes)
    char *cp; 
size_t nbytes;
{   
    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;
    /*
     * First the malloc/copy cases
     */
    expensive = 0;
    if ( i == 0xff ) {
	Handle hand;

	hand = * (Handle *) ((Ptr) op - sizeof(Handle));
	maxsize = GetHandleSize(hand) - sizeof(Handle);
	expensive = 1;
    } else {
	maxsize = 1 << (i+3);
	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(newp, cp, 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(s)
    char *s;
{
    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

/*
 *----------------------------------------------------------------------
 *
 * SysAlloc --
 *
 *	Allocate a new block of memory free from the System.
 *
 * Results:
 *	Returns a pointer to a new block of memory.
 *
 * Side effects:
 *	May obtain memory from app or sys space.  Info is added to
 *	overhead lists etc..
 *
 *----------------------------------------------------------------------
 */

static void *
SysAlloc(
	 long size,
	 int high)
{
    Handle hand = NULL;
    ListEl * newMemoryRecord;
    
    if (!(memoryFlags & MEMORY_ALL_SYS)) {
	hand = NewHandle(size + sizeof(Handle));
    }
    if (hand != NULL) {
	newMemoryRecord = (ListEl *) NewPtr(sizeof(ListEl));
	if (newMemoryRecord == NULL) {
	    DisposeHandle(hand);
	    return NULL;
	}
	newMemoryRecord->memoryHandle = hand;
	newMemoryRecord->next = appMemory;
	appMemory = newMemoryRecord;
    } else {
	/*
	 * Ran out of memory in application space.  Lets try to get 
	 * more memory from system.  Otherwise, we return NULL to
	 * denote failure.
	 */
	high = false;
	hand = NewHandleSys(size);
	if (hand == NULL) {
	    return NULL;
	}
	if (systemMemory == NULL) {
	    /*
	     * This is the first time we've attempted to allocate memory
	     * directly from the system heap.  We need to now install the
	     * exit handle to ensure the memory is cleaned up.
	     */
	    /* TclMacInstallExitToShellPatch(CleanUpExitProc); */
	}
	newMemoryRecord = (ListEl *) NewPtrSys(sizeof(ListEl));
	if (newMemoryRecord == NULL) {
	    DisposeHandle(hand);
	    return NULL;
	}
	newMemoryRecord->memoryHandle = hand;
	newMemoryRecord->next = systemMemory;
	systemMemory = newMemoryRecord;
    }
    if (high) {
	HLockHi(hand);
    } else {
	HLock(hand);
    }
    (** (Handle **) hand) = hand;
    
    return (*hand + sizeof(Handle));
}

/*
 *----------------------------------------------------------------------
 *
 * SysFree --
 *
 *	Free memory that we aloocated back to the system.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Memory is freed.
 *
 *----------------------------------------------------------------------
 */

static void
SysFree(void * ptr)
{
    Handle hand;
    OSErr err;

    hand = * (Handle *) ((Ptr) ptr - sizeof(Handle));
    DisposeHandle(hand);
    err = MemError();
}

/*
 *----------------------------------------------------------------------
 *
 * CleanUpExitProc --
 *
 *	This procedure is invoked as an exit handler when ExitToShell
 *	is called.  It removes any memory that was allocated directly
 *	from the system heap.  This must be called when the application
 *	quits or the memory will never be freed.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May free memory in the system heap.
 *
 *----------------------------------------------------------------------
 */

static pascal void
CleanUpExitProc()
{
    ListEl * memRecord;
    
    while (systemMemory != NULL) {
	memRecord = systemMemory;
	systemMemory = memRecord->next;
	DisposeHandle(memRecord->memoryHandle);
	DisposePtr((void *) memRecord);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * FreeAllMemory --
 *
 *	This procedure frees all memory blocks allocated by the memory
 *	sub-system.  Make sure you don't have any code that references
 *	any malloced data!
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Frees all memory allocated by TclpAlloc.
 *
 *----------------------------------------------------------------------
 */

void
FreeAllMemory()
{
    ListEl * memRecord;
    
    while (systemMemory != NULL) {
	memRecord = systemMemory;
	systemMemory = memRecord->next;
	DisposeHandle(memRecord->memoryHandle);
	DisposePtr((void *) memRecord);
    }
    while (appMemory != NULL) {
	memRecord = appMemory;
	appMemory = memRecord->next;
	DisposeHandle(memRecord->memoryHandle);
	DisposePtr((void *) memRecord);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ConfigureMemory --
 *
 *	This procedure sets certain flags in this file that control
 *	how memory is allocated and managed.  This call must be made
 *	before any call to TclpAlloc is made.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Certain state will be changed.
 *
 *----------------------------------------------------------------------
 */

void
ConfigureMemory(
    int flags)
{
    memoryFlags = flags;
}
