maths.h

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/* xoreos - A reimplementation of BioWare's Aurora engine
 *
 * xoreos is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 *
 * xoreos 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with xoreos. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef COMMON_MATHS_H
#define COMMON_MATHS_H

#include <cmath>
#include <cfloat>

#include "src/common/system.h"
#include "src/common/types.h"

#ifndef M_SQRT1_2
    #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
#endif

#ifndef M_PI
    #define M_PI 3.14159265358979323846
#endif

#ifndef FLT_MIN
    #define FLT_MIN 1E-37
#endif

#ifndef FLT_MAX
    #define FLT_MAX 1E+37
#endif

#ifndef INT32_MIN
    #define INT32_MIN ((int32) 0x80000000)
#endif

#ifndef INT32_MAX
    #define INT32_MAX ((int32) 0x7FFFFFFF)
#endif

namespace Common {

struct Complex {
    float re, im;
};


#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
static inline int intLog2(uint32 v) {
    // This is a slightly optimized implementation of log2 for natural numbers
    // targeting gcc. It also saves some binary size over our fallback
    // implementation, since it does not need any table.
    if (v == 0)
        return -1;
    else
        // This is really "sizeof(unsigned int) * CHAR_BIT - 1" but using 8
        // instead of CHAR_BIT is sane enough and it saves us from including
        // limits.h
        return (sizeof(unsigned int) * 8 - 1) - __builtin_clz(v);
}
#else
// See http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup

extern const int8 intLog2Table256[256];
static inline int intLog2(uint32 v) {
    register uint32 t, tt;

    if ((tt = v >> 16))
        return (t = tt >> 8) ? 24 + intLog2Table256[t] : 16 + intLog2Table256[tt];
    else
        return (t =  v >> 8) ?  8 + intLog2Table256[t] : intLog2Table256[v];
}
#endif

static inline float rad2deg(float rad) {
    return rad * 180.0f / M_PI;
}

static inline float deg2rad(float deg) {
    return deg * M_PI / 180.0f;
}

} // End of namespace Common

#endif // COMMON_MATHS_H