Annotation of gforth/engine/ecvt.c, revision 1.9

1.3       anton       1: /* cheap ecvt replacement
                      2: 
1.9     ! anton       3:   Copyright (C) 1998,2000,2007 Free Software Foundation, Inc.
1.3       anton       4: 
                      5:   This file is part of Gforth.
                      6: 
                      7:   Gforth is free software; you can redistribute it and/or
                      8:   modify it under the terms of the GNU General Public License
                      9:   as published by the Free Software Foundation; either version 2
                     10:   of the License, or (at your option) any later version.
                     11: 
                     12:   This program is distributed in the hope that it will be useful,
                     13:   but WITHOUT ANY WARRANTY; without even the implied warranty of
                     14:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     15:   GNU General Public License for more details.
                     16: 
                     17:   You should have received a copy of the GNU General Public License
                     18:   along with this program; if not, write to the Free Software
1.7       anton      19:   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
1.3       anton      20: */
1.1       anton      21: 
1.2       pazsan     22: #include <stdio.h>
1.1       anton      23: #include "config.h"
                     24: #include <math.h>
                     25: extern double floor(double);
                     26: extern double pow10(double);
                     27: 
                     28: #define MAXCONV 0x40
                     29: char scratch[MAXCONV];
                     30: 
                     31: char* ecvt(double x, int len, int* exp, int* sign)
                     32: {
                     33:    int i, j;
                     34:    double z;
                     35:    
1.8       anton      36:    if (isnan(x)) {
                     37:      *sign=0;
                     38:      *exp=0;
                     39:      return "nan";
                     40:    }
                     41:    if (isinf(x)) {
                     42:      *sign=0; /* this mimics the glibc ecvt */
                     43:      *exp=0;
                     44:      if (x<0)
                     45:        return "-inf";
                     46:      else
                     47:        return "inf";
                     48:    }
                     49:        
1.1       anton      50:    if(len > (MAXCONV-1)) len = MAXCONV-1;
                     51:    
                     52:    if(x<0)
                     53:      {
                     54:        *sign = 1;
                     55:        x = -x;
                     56:      }
                     57:    else
                     58:      {
                     59:        *sign = 0;
                     60:      }
                     61: 
                     62:    if(x==0)
                     63:        *exp=-1;
                     64:    else
                     65:      *exp=(int)floor(log10(x));
                     66:    x = x / pow10((double)*exp);
                     67:    
                     68:    *exp += 1;
                     69:    
                     70:    for(i=0; i < len; i++)
                     71:      {
                     72:        z=floor(x);
1.5       pazsan     73:        if(z<0) z = 0;
1.1       anton      74:        scratch[i]='0'+(char)((int)z);
                     75:        x = (x-z)*10;
                     76:      }
                     77:    
                     78:    if((x >= 5) && i)
                     79:      {
                     80:        for(j=i-1; j>=0; j--)
                     81:          {
                     82:             if(scratch[j]!='9')
                     83:               {
                     84:                  scratch[j]+=1; break;
                     85:               }
                     86:             else
                     87:               {
                     88:                  scratch[j]='0';
                     89:               }
                     90:          }
1.2       pazsan     91:        if(j<0)
1.1       anton      92:          {
                     93:             scratch[0]='1';
                     94:             *exp += 1;
                     95:          }
                     96:      }
                     97:    
                     98:    scratch[i]='\0';
                     99:    
                    100:    return scratch;
                    101: }
                    102: 
                    103: #ifdef TEST
                    104: int main(int argc, char ** argv)
                    105: {
                    106:    int a, b;
1.2       pazsan    107:    char * conv=ecvt(9e0,20,&a,&b);
1.1       anton     108:    
1.2       pazsan    109:    printf("ecvt Test: %f -> %s, %d, %d\n",9e0,conv,a,b);
1.1       anton     110: }
                    111: #endif
1.5       pazsan    112: 

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