root/3rdparty/libjasper/jpc_math.c

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DEFINITIONS

This source file includes following definitions.
  1. jpc_floorlog2
  2. jpc_firstone

/*
 * Copyright (c) 1999-2000 Image Power, Inc. and the University of
 *   British Columbia.
 * Copyright (c) 2001-2002 Michael David Adams.
 * All rights reserved.
 */

/* __START_OF_JASPER_LICENSE__
 *
 * JasPer License Version 2.0
 *
 * Copyright (c) 2001-2006 Michael David Adams
 * Copyright (c) 1999-2000 Image Power, Inc.
 * Copyright (c) 1999-2000 The University of British Columbia
 *
 * All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person (the
 * "User") obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without restriction,
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 * publish, distribute, and/or sell copies of the Software, and to permit
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 * includes the disclaimer below) shall be included in all copies or
 * substantial portions of the Software.
 *
 * 2.  The name of a copyright holder shall not be used to endorse or
 * promote products derived from the Software without specific prior
 * written permission.
 *
 * THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS
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 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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 * THE FAILURE OF THE SOFTWARE OR SYSTEM COULD LEAD DIRECTLY TO DEATH,
 * PERSONAL INJURY, OR SEVERE PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH
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 */

/*
 * Math Library
 *
 * $Id: jpc_math.c,v 1.2 2008-05-26 09:40:52 vp153 Exp $
 */

/******************************************************************************\
* Includes
\******************************************************************************/

#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <stdarg.h>

#include "jpc_math.h"

/******************************************************************************\
* Miscellaneous Functions
\******************************************************************************/

/* Calculate the integer quantity floor(log2(x)), where x is a positive
  integer. */
int jpc_floorlog2(int x)
{
    int y;

    /* The argument must be positive. */
    assert(x > 0);

    y = 0;
    while (x > 1) {
        x >>= 1;
        ++y;
    }
    return y;
}

/* Calculate the bit position of the first leading one in a nonnegative
  integer. */
/* This function is the basically the same as ceillog2(x), except that the
  allowable range for x is slightly different. */
int jpc_firstone(int x)
{
    int n;

    /* The argument must be nonnegative. */
    assert(x >= 0);

    n = -1;
    while (x > 0) {
        x >>= 1;
        ++n;
    }
    return n;
}

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