str_ftoa.c

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/* float to string, internal usage */

#include "fb.h"

char *fb_hFloat2Str( double val, char *buffer, int digits, int mask )
{
        ssize_t len, maxlen;
        char *p;
        char fmtstr[16], *fstr;

        if( mask & FB_F2A_ADDBLANK )
                p = &buffer[1];
        else
                p = buffer;

        switch( digits )
        {
        case 7:
                fstr = (char *)&"%.7g";
                break;
        case 16:
                fstr = (char *)&"%.16g";
                break;
        default:
                sprintf( fmtstr, "%%.%dg", digits );
                fstr = &fmtstr[0];
        }

        maxlen = 1+digits+6+1;

        len = snprintf( p, maxlen, fstr, val );

        if( len <= 0 || len >= maxlen )
        {
                buffer[0] = '\0';
                return NULL;
        }

        if( len > 0 )
        {
                /* skip the dot at end if any */
                if( len > 0 )
                        if( p[len-1] == '.' )
                                p[len-1] = '\0';
        }

        /* */
        if( (mask & FB_F2A_ADDBLANK) > 0 )
        {
                if( p[0] != '-' )
                {
                        buffer[0] = ' ';
                        return &buffer[0];
                }
                else
                        return p;
        }
        else
                return p;
}