/* Implementation of Objective C NeXT-compatible Storage object
     Copyright (C) 1993,1994, 1996 Free Software Foundation, Inc.

     Written by:  Kresten Krab Thorup <krab@iesd.auc.dk>
     Dept. of Mathematics and Computer Science, Aalborg U., Denmark

     This file is part of the GNUstep Base Library.

     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.

     This library 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
     Library General Public License for more details.

     You should have received a copy of the GNU Library General Public
     License along with this library; if not, write to the Free
     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* #include <config.h> */
#include "Storage.h"
#include <string.h>
#include <strings.h>

#define GNU_STORAGE_NTH(x, N)                  \
    ({GNUStorageId* __s = (GNUStorageId*) (x); \
      (void*) (((char*) __s->dataPtr) + (__s->elementSize * (N))); })
#define STORAGE_NTH(N) GNU_STORAGE_NTH (self, N)

typedef  struct {
	@defs (Storage)
} GNUStorageId;

@implementation Storage

+ (id) initialize
{
	if (self == [Storage class])
		[self setVersion: 0];       /* beta release */
	return self;
}

// INITIALIZING, FREEING;

- (id) initCount: (NSUInteger)numSlots elementSize: (NSUInteger)sizeInBytes
   description: (const char *)
   elemDesc;
{
	[super init];
	numElements = numSlots;
	maxElements = (numSlots > 0) ? numSlots : 1;
	elementSize = sizeInBytes;
	description = elemDesc;
	dataPtr = (void *) objc_malloc (maxElements * elementSize);
	bzero (dataPtr, numElements * elementSize);
	return self;
}

- (id) init
{
	return [self   initCount: 1 elementSize: sizeof (id)
	             description: @encode (id)];
}

- (void) dealloc
{
	if (dataPtr)
		free (dataPtr);
	[super dealloc];
}

- (const char *) description
{
	return description;
}

// COPYING;

- (id) copy
{
	Storage  *c = [super copy];

	c->dataPtr = (void *) objc_malloc (maxElements * elementSize);
	memcpy (c->dataPtr, dataPtr, numElements * elementSize);
	return c;
}

// COMPARING TWO STORAGES;

- (BOOL) isEqual: anObject
{
	if ([anObject isKindOfClass: [Storage class]]
	    && [anObject count] == [self count]
	    && !memcmp (((GNUStorageId *) anObject)->dataPtr,
	                dataPtr, numElements * elementSize))
		return YES;
	else
		return NO;
}

// MANAGING THE STORAGE CAPACITY;

static inline void
_makeRoomForAnotherIfNecessary (Storage * self)
{
	if (self->numElements == self->maxElements) {
		self->maxElements *= 2;
		self->dataPtr = (void *)
		                objc_realloc (self->dataPtr,
		                              self->maxElements * self->elementSize);
	}
}

static inline void
_shrinkIfDesired (Storage * self)
{
	if (self->numElements < (self->maxElements / 2)) {
		self->maxElements /= 2;
		self->dataPtr = (void *)
		                objc_realloc (self->dataPtr,
		                              self->maxElements * self->elementSize);
	}
}

- (id) setAvailableCapacity: (NSUInteger)numSlots
{
	if (numSlots > numElements) {
		maxElements = numSlots;
		dataPtr = (void *) objc_realloc (dataPtr, maxElements * elementSize);
	}
	return self;
}

- (id) setNumSlots: (NSUInteger)numSlots
{
	if (numSlots > numElements) {
		maxElements = numSlots;
		dataPtr = (void *) objc_realloc (dataPtr, maxElements * elementSize);
		bzero (STORAGE_NTH (numElements),
		       (maxElements - numElements) * elementSize);
	} else if (numSlots < numElements) {
		numElements = numSlots;
		_shrinkIfDesired (self);
	}
	return self;
}

/* Manipulating objects by index */

#define CHECK_INDEX(IND) if (IND >= numElements) return 0

- (NSUInteger) count
{
	return numElements;
}

- (void *) elementAt: (NSUInteger)index
{
	CHECK_INDEX (index);
	return STORAGE_NTH (index);
}

- (id) addElement: (void *)anElement
{
	_makeRoomForAnotherIfNecessary (self);
	memcpy (STORAGE_NTH (numElements), anElement, elementSize);
	numElements++;
	return self;
}

- (id) insertElement: (void *)
   anElement at: (NSUInteger)index
{
	NSUInteger  i;

	CHECK_INDEX (index);
	_makeRoomForAnotherIfNecessary (self);
#ifndef STABLE_MEMCPY
	for (i = numElements; i >= index; i--)
		memcpy (STORAGE_NTH (i + 1), STORAGE_NTH (i), elementSize);

#else
	memcpy (STORAGE_NTH (index + 1),
	        STORAGE_NTH (index), elementSize * (numElements - index));
#endif
	memcpy (STORAGE_NTH (i), anElement, elementSize);
	numElements++;
	return self;
}

- (id) removeElementAt: (NSUInteger)index
{
	NSUInteger  i;

	CHECK_INDEX (index);
	numElements--;
#ifndef STABLE_MEMCPY
	for (i = index; i < numElements; i++)
		memcpy (STORAGE_NTH (i), STORAGE_NTH (i + 1), elementSize);

#else
	memcpy (STORAGE_NTH (index),
	        STORAGE_NTH (index + 1), elementSize * (numElements - index - 1));
#endif
	_shrinkIfDesired (self);
	return self;
}

- (id) removeLastElement
{
	if (numElements) {
		numElements--;
		_shrinkIfDesired (self);
	}
	return self;
}

- (id) replaceElementAt: (NSUInteger)
   index with: (void *)newElement
{
	CHECK_INDEX (index);
	memcpy (STORAGE_NTH (index), newElement, elementSize);
	return self;
}

/* Emptying the Storage */

- (id) empty
{
	numElements = 0;
	maxElements = 1;
	dataPtr = (void *) objc_realloc (dataPtr, maxElements * elementSize);
	return self;
}

+ (id) new
{
	return [[self alloc] init];
}

+ (id) newCount: (NSUInteger)
   count elementSize: (NSUInteger)sizeInBytes
   description: (const char *)descriptor
{
	return [[self alloc] initCount: count elementSize: sizeInBytes description:
	        descriptor];
}

@end