assimp/code/fast_atof.h

115 lines
2.1 KiB
C++

// Copyright (C) 2002-2007 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
// Adapted to the ASSIMP library because the builtin atof indeed takes AGES to parse a
// float inside a large string. Before parsing, it does a strlen on the given point.
#ifndef __FAST_A_TO_F_H_INCLUDED__
#define __FAST_A_TO_F_H_INCLUDED__
#include <math.h>
namespace Assimp
{
const float fast_atof_table[16] = { // we write [16] here instead of [] to work around a swig bug
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 unsigned int strtol10( const char* in, const char** out=0)
{
unsigned int value = 0;
while ( 1 )
{
if ( *in < '0' || *in > '9' )
break;
value = ( value * 10 ) + ( *in - '0' );
++in;
}
if (out)
*out = in;
return value;
}
//! Provides a fast function for converting a string into a float,
//! about 6 times faster than atof in win32.
// If you find any bugs, please send them to me, niko (at) irrlicht3d.org.
inline const char* fast_atof_move( const char* c, float& out)
{
bool inv = false;
const char *t;
float f;
if (*c=='-')
{
++c;
inv = true;
}
//f = (float)strtol(c, &t, 10);
f = (float) strtol10 ( c, &c );
if (*c == '.')
{
++c;
//float pl = (float)strtol(c, &t, 10);
float pl = (float) strtol10 ( c, &t );
pl *= fast_atof_table[t-c];
f += pl;
c = t;
if (*c == 'e')
{
++c;
//float exp = (float)strtol(c, &t, 10);
bool einv = (*c=='-');
if (einv)
++c;
float exp = (float)strtol10(c, &c);
if (einv)
exp *= -1.0f;
f *= pow(10.0f, exp);
}
}
if (inv)
f *= -1.0f;
out = f;
return c;
}
inline float fast_atof(const char* c)
{
float ret;
fast_atof_move(c, ret);
return ret;
}
} // end of namespace Assimp
#endif