fast_atof.h

// Copyright (C) 2002-2005 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine" and the "irrXML" project.
// For conditions of distribution and use, see copyright notice in irrlicht.h and irrXML.h

#ifndef __FAST_A_TO_F_H_INCLUDED__
#define __FAST_A_TO_F_H_INCLUDED__

#include <stdlib.h>
#include <math.h>

namespace irr
{
namespace core
{

const float fast_atof_table[] = {
                                                                                0.f,
                                                                                0.1f,
                                                                                0.01f,
                                                                                0.001f,
                                                                                0.0001f,
                                                                                0.00001f,
                                                                                0.000001f,
                                                                                0.0000001f,
                                                                                0.00000001f,
                                                                                0.000000001f,
                                                                                0.0000000001f,
                                                                                0.00000000001f,
                                                                                0.000000000001f,
                                                                                0.0000000000001f,
                                                                                0.00000000000001f,
                                                                                0.000000000000001f
                                                                        };

inline char* fast_atof_move(char* c, float& out)
{
        bool inv = false;
        char *t;
        float f;

        if (*c=='-')
        {
                c++;
                inv = true;
        }

        f = (float)strtol(c, &t, 10);

        c = t;

        if (*c == '.')
        {
                c++;

                float pl = (float)strtol(c, &t, 10);
                pl *= fast_atof_table[t-c];

                f += pl;

                c = t;

                if (*c == 'e')
                {
                        ++c;
                        float exp = (float)strtol(c, &t, 10);
                        f *= (float)pow(10.0f, exp);
                        c = t;
                }
        }

        if (inv)
                f *= -1.0f;

        out = f;
        return c;
}

inline const char* fast_atof_move_const(const char* c, float& out)
{
        bool inv = false;
        char *t;
        float f;

        if (*c=='-')
        {
                c++;
                inv = true;
        }

        f = (float)strtol(c, &t, 10);

        c = t;

        if (*c == '.')
        {
                c++;

                float pl = (float)strtol(c, &t, 10);
                pl *= fast_atof_table[t-c];

                f += pl;

                c = t;

                if (*c == 'e')
                {
                        ++c;
                        f32 exp = (f32)strtol(c, &t, 10);
                        f *= (f32)powf(10.0f, exp);
                        c = t;
                }
        }

        if (inv)
                f *= -1.0f;

        out = f;
        return c;
}


inline float fast_atof(const char* c)
{
        float ret;
        fast_atof_move_const(c, ret);
        return ret;
}

} // end namespace core
}// end namespace irr

#endif

---