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sortix--sortix/libc/atof.cpp

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2013-03-19 17:10:27 -04:00
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
atof.cpp
Converts floats represented as strings to binary representation.
*******************************************************************************/
#include <stdlib.h>
#include <stdio.h>
// TODO: This horribly hacky code is taken from sdlquake's common.c, which is
// licensed under the GPL. Since most Sortix software is GPL-compatible
// this will do for now. It's a temporary measure until I get around to
// writing a real strtod function - most of them are true horrors.
extern "C" double atof(const char* str)
{
int sign = *str == '-' ? (str++, -1) : 1;
double val = 0.0;
if ( str[0] == '0' && (str[1] == 'x' || str[1] == 'X') )
{
str += 2;
while ( true )
{
char c = *str++;
if ( '0' <= c && c <= '9' )
val = val * 16 + c - '0';
else if ( 'a' <= c && c <= 'f' )
val = val * 16 + c - 'a' + 10;
else if ( 'A' <= c && c <= 'F' )
val = val * 16 + c - 'A' + 10;
else
return val * sign;
}
}
int decimal = -1;
int total = 0;
while ( true )
{
char c = *str++;
if (c == '.')
{
decimal = total;
continue;
}
if ( c < '0' || c > '9' )
break;
val = val * 10 + c - '0';
total++;
}
if ( decimal == -1 )
return val * sign;
while ( decimal < total )
{
val /= 10;
total--;
}
return val * sign;
}