vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
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jpc_math.c (4323B)

      1 /*
      2  * Copyright (c) 1999-2000 Image Power, Inc. and the University of
      3  *   British Columbia.
      4  * Copyright (c) 2001-2002 Michael David Adams.
      5  * All rights reserved.
      6  */
      7 
      8 /* __START_OF_JASPER_LICENSE__
      9  * 
     10  * JasPer License Version 2.0
     11  * 
     12  * Copyright (c) 1999-2000 Image Power, Inc.
     13  * Copyright (c) 1999-2000 The University of British Columbia
     14  * Copyright (c) 2001-2003 Michael David Adams
     15  * 
     16  * All rights reserved.
     17  * 
     18  * Permission is hereby granted, free of charge, to any person (the
     19  * "User") obtaining a copy of this software and associated documentation
     20  * files (the "Software"), to deal in the Software without restriction,
     21  * including without limitation the rights to use, copy, modify, merge,
     22  * publish, distribute, and/or sell copies of the Software, and to permit
     23  * persons to whom the Software is furnished to do so, subject to the
     24  * following conditions:
     25  * 
     26  * 1.  The above copyright notices and this permission notice (which
     27  * includes the disclaimer below) shall be included in all copies or
     28  * substantial portions of the Software.
     29  * 
     30  * 2.  The name of a copyright holder shall not be used to endorse or
     31  * promote products derived from the Software without specific prior
     32  * written permission.
     33  * 
     34  * THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS
     35  * LICENSE.  NO USE OF THE SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER
     36  * THIS DISCLAIMER.  THE SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
     37  * "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
     38  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
     39  * PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.  IN NO
     40  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
     41  * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
     42  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
     43  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     44  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.  NO ASSURANCES ARE
     45  * PROVIDED BY THE COPYRIGHT HOLDERS THAT THE SOFTWARE DOES NOT INFRINGE
     46  * THE PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OF ANY OTHER ENTITY.
     47  * EACH COPYRIGHT HOLDER DISCLAIMS ANY LIABILITY TO THE USER FOR CLAIMS
     48  * BROUGHT BY ANY OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL
     49  * PROPERTY RIGHTS OR OTHERWISE.  AS A CONDITION TO EXERCISING THE RIGHTS
     50  * GRANTED HEREUNDER, EACH USER HEREBY ASSUMES SOLE RESPONSIBILITY TO SECURE
     51  * ANY OTHER INTELLECTUAL PROPERTY RIGHTS NEEDED, IF ANY.  THE SOFTWARE
     52  * IS NOT FAULT-TOLERANT AND IS NOT INTENDED FOR USE IN MISSION-CRITICAL
     53  * SYSTEMS, SUCH AS THOSE USED IN THE OPERATION OF NUCLEAR FACILITIES,
     54  * AIRCRAFT NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL
     55  * SYSTEMS, DIRECT LIFE SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH
     56  * THE FAILURE OF THE SOFTWARE OR SYSTEM COULD LEAD DIRECTLY TO DEATH,
     57  * PERSONAL INJURY, OR SEVERE PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH
     58  * RISK ACTIVITIES").  THE COPYRIGHT HOLDERS SPECIFICALLY DISCLAIM ANY
     59  * EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR HIGH RISK ACTIVITIES.
     60  * 
     61  * __END_OF_JASPER_LICENSE__
     62  */
     63 
     64 /*
     65  * Math Library
     66  *
     67  * $Id: jpc_math.c 1918 2005-07-24 14:12:08Z baford $
     68  */
     69 
     70 /******************************************************************************\
     71 * Includes
     72 \******************************************************************************/
     73 
     74 #include <assert.h>
     75 #include <stdio.h>
     76 #include <string.h>
     77 #include <math.h>
     78 #include <stdlib.h>
     79 #include <stdarg.h>
     80 
     81 #include "jpc_math.h"
     82 
     83 /******************************************************************************\
     84 * Miscellaneous Functions
     85 \******************************************************************************/
     86 
     87 /* Calculate the integer quantity floor(log2(x)), where x is a positive
     88   integer. */
     89 int jpc_floorlog2(int x)
     90 {
     91 	int y;
     92 
     93 	/* The argument must be positive. */
     94 	assert(x > 0);
     95 
     96 	y = 0;
     97 	while (x > 1) {
     98 		x >>= 1;
     99 		++y;
    100 	}
    101 	return y;
    102 }
    103 
    104 /* Calculate the bit position of the first leading one in a nonnegative
    105   integer. */
    106 /* This function is the basically the same as ceillog2(x), except that the
    107   allowable range for x is slightly different. */
    108 int jpc_firstone(int x)
    109 {
    110 	int n;
    111 
    112 	/* The argument must be nonnegative. */
    113 	assert(x >= 0);
    114 
    115 	n = -1;
    116 	while (x > 0) {
    117 		x >>= 1;
    118 		++n;
    119 	}
    120 	return n;
    121 }