/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */

#ifndef jsbit_h___
#define jsbit_h___

#include "jstypes.h"
JS_BEGIN_EXTERN_C

/*
** A jsbitmap_t is a long integer that can be used for bitmaps
*/
typedef JSUword     jsbitmap_t;     /* NSPR name, a la Unix system types */
typedef jsbitmap_t  jsbitmap;       /* JS-style scalar typedef name */

#define JS_TEST_BIT(_map,_bit) \
    ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] & (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
#define JS_SET_BIT(_map,_bit) \
    ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] |= (1L << ((_bit) & (JS_BITS_PER_WORD-1))))
#define JS_CLEAR_BIT(_map,_bit) \
    ((_map)[(_bit)>>JS_BITS_PER_WORD_LOG2] &= ~(1L << ((_bit) & (JS_BITS_PER_WORD-1))))

/*
** Compute the log of the least power of 2 greater than or equal to n
*/
extern JS_PUBLIC_API(JSIntn) JS_CeilingLog2(JSUint32 i);

/*
** Compute the log of the greatest power of 2 less than or equal to n
*/
extern JS_PUBLIC_API(JSIntn) JS_FloorLog2(JSUint32 i);

/*
** Macro version of JS_CeilingLog2: Compute the log of the least power of
** 2 greater than or equal to _n. The result is returned in _log2.
*/
#define JS_CEILING_LOG2(_log2,_n)   \
  JS_BEGIN_MACRO                    \
    JSUint32 j_ = (JSUint32)(_n); 	\
    (_log2) = 0;                    \
    if ((j_) & ((j_)-1))            \
	(_log2) += 1;               \
    if ((j_) >> 16)                 \
	(_log2) += 16, (j_) >>= 16; \
    if ((j_) >> 8)                  \
	(_log2) += 8, (j_) >>= 8;   \
    if ((j_) >> 4)                  \
	(_log2) += 4, (j_) >>= 4;   \
    if ((j_) >> 2)                  \
	(_log2) += 2, (j_) >>= 2;   \
    if ((j_) >> 1)                  \
	(_log2) += 1;               \
  JS_END_MACRO

/*
** Macro version of JS_FloorLog2: Compute the log of the greatest power of
** 2 less than or equal to _n. The result is returned in _log2.
**
** This is equivalent to finding the highest set bit in the word.
*/
#define JS_FLOOR_LOG2(_log2,_n)   \
  JS_BEGIN_MACRO                    \
    JSUint32 j_ = (JSUint32)(_n); 	\
    (_log2) = 0;                    \
    if ((j_) >> 16)                 \
	(_log2) += 16, (j_) >>= 16; \
    if ((j_) >> 8)                  \
	(_log2) += 8, (j_) >>= 8;   \
    if ((j_) >> 4)                  \
	(_log2) += 4, (j_) >>= 4;   \
    if ((j_) >> 2)                  \
	(_log2) += 2, (j_) >>= 2;   \
    if ((j_) >> 1)                  \
	(_log2) += 1;               \
  JS_END_MACRO

JS_END_EXTERN_C
#endif /* jsbit_h___ */
