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) 2001-2006 Michael David Adams
13 * Copyright (c) 1999-2000 Image Power, Inc.
14 * Copyright (c) 1999-2000 The University of British Columbia
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,v 1.2 2008-05-26 09:40:52 vp153 Exp $
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. */
jpc_floorlog2(int x)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. */
jpc_firstone(int x)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 }
122