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// ============================================================================
//        __
//   \\__/ o\    (C) 2015  Robert Finch, Stratford
//    \  __ /    All rights reserved.
//     \/_//     robfinch<remove>@finitron.ca
//       ||
//
// prtdbl.c
// Print a string representation of a double.
//
// This source file 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.                                      
//                                                                          
// This source file 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 General Public License for more details.                             
//                                                                          
// You should have received a copy of the GNU General Public License        
// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
//                                                                          
// ============================================================================
//
extern pascal void putchar(char ch);
extern pascal int putstr(char *p, int maxchars);
 
// Put a string representation of a double into a char buffer.
// Buffer must be at least 30 characters in size and at least width characters
// in size.
 
pascal int sprtdbl(char *buf, double dbl, int width, int precision, char E)
{
    int ndx;
    int exp, expcnt;
    int digit;
    int nn;
    int digits_before_decpt;
 
    ndx = 0;
    if (dbl < 0.0) {
        dbl = -dbl;
        buf[0] = '-';
        ndx++;
    }
    if (dbl==0.0) {
        buf[ndx]='0';
        ndx++;
        buf[ndx]='\0';
        return;
    }
    exp = 0;
    while (dbl < 1.0) {
        dbl *= 1000000.0;
        exp -= 6;  
    }
    while (dbl > 100000.0) {
        dbl /= 10.0;
        exp++;  
    }
    while (dbl < 100000.0) {
        dbl *= 10.0;
        exp--;
    }
    digits_before_decpt = 1;
    expcnt = exp+7;
    if (exp+7 >= 0 && exp+7 < 8) {
        digits_before_decpt = exp+7;
        digits_before_decpt--;
        expcnt = 2;
    }
j1:;
    expcnt -= 2;
    exp = digits_before_decpt;
    if (exp <= 0) {
        buf[ndx] = '.';
        ndx++;
        if (exp < 0) {
           buf[ndx] = '0';
           ndx++;
        }
    }
    for (nn = 0; nn < 16 && precision > 0; nn++) {
        digit = 0;
        while (dbl > 100000.0) {
            dbl -= 100000.0;
            digit++;
        }
        buf[ndx] = digit + '0';
        ndx++;
        exp--;
        if (exp==0) {
           buf[ndx] = '.';
           ndx++;
        }
        else if (exp < 0)
            precision--;
        dbl *= 10.0;
    }
    do {
        ndx--;
    } while(buf[ndx]=='0');
    ndx++;
    if (expcnt==0) {
        buf[ndx]='\0';
        goto prt;
    }
    buf[ndx] = E;
    ndx++;
    if (expcnt < 0) {
        buf[ndx]='-';
        ndx++;
        expcnt = -expcnt;
    }
    else {
         buf[ndx]='+';
         ndx++;
    }
    digit = 0;
    while (expcnt > 1000) {
        expcnt -= 1000;
        digit++;
    }
    buf[ndx] = digit + '0';
    ndx++;
    digit = 0;
    while (expcnt > 100) {
        expcnt -= 100;
        digit++;
    }
    buf[ndx] = digit + '0';
    ndx++;
    digit = 0;
    while (expcnt > 10) {
        expcnt -= 10;
        digit++;
    }
    buf[ndx] = digit + '0';
    ndx++;
    digit = 0;
    while (expcnt > 0) {
        expcnt -= 1;
        digit++;
    }
    buf[ndx] = digit + '0';
    ndx++;
    buf[ndx] = '\0';
prt:;
    // pad left
    if (width > 0) {
        if (ndx < width) {
            for (nn = 29; nn >= width-ndx; nn--)
                buf[nn] = buf[nn-(width-ndx)];
            for (; nn >= 0; nn--)
                buf[nn] = ' ';
        }
    }
    // pad right
    if (width < 0) {
        width = -width;
        while (ndx < width) {
            buf[ndx]=' ';
            ndx++;
        }
        buf[ndx]='\0';
    }
    return ndx;
}
 
pascal int prtdbl(double dbl, int width, int precision, char E)
{
    static char buf[200];
    int nn;
 
    if (width > 199)
       width = 199;
    if (width < -199)
       width = -199;
    nn = sprtdbl(buf, dbl, width, precision, E);
    putstr(buf,width);
    return nn;
}