85 lines
1.6 KiB
C
85 lines
1.6 KiB
C
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/* atof.c: converts an ASCII string to float
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Copyright (C) 2003 Jesus Calvino-Fraga, jesusc@ieee.org
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include <stdlib.h>
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#include <ctype.h>
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float atof(const char * s)
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{
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float value, fraction;
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char iexp;
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char sign;
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//Skip leading blanks
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while (isspace(*s)) s++;
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//Get the sign
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if (*s == '-')
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{
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sign=1;
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s++;
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}
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else
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{
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sign=0;
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if (*s == '+') s++;
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}
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//Get the integer part
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for (value=0.0f; isdigit(*s); s++)
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{
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value=10.0f*value+(*s-'0');
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}
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//Get the fraction
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if (*s == '.')
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{
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s++;
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for (fraction=0.1f; isdigit(*s); s++)
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{
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value+=(*s-'0')*fraction;
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fraction*=0.1f;
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}
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}
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//Finally, the exponent (not very efficient, but enough for now)
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if (toupper(*s)=='E')
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{
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s++;
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iexp=(char)atoi(s);
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{
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while(iexp!=0)
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{
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if(iexp<0)
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{
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value*=0.1f;
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iexp++;
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}
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else
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{
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value*=10.0f;
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iexp--;
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}
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}
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}
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}
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if(sign) value*=-1.0f;
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return (value);
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}
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