/*
** Copyright (c) Lew Pitcher, 1999, 2008
*/
#include <stdio.h>

#define P   5000    /* number of multiply iterations    */

#define N   1776    /* number of divide iterations      *

#define X   2078    /* number of bytes in fraction part */
#define I   1       /* number of bytes in integer part  */

char e[I+X];        /* holds e fixed point binary value */

int main(void)
{
    void divide(char *, unsigned, unsigned),
         multiply(char *, unsigned, unsigned);

    unsigned n, /* divisor for calculation loop */
             p; /* precision for print loop     */

    e[0] = 1;   /* start the series at 1.anything   */
    for (n = N; n > 0; --n)
    {
        divide(e,n,I+X);
        e[0] += 1;
    }

    fputs(" e == ",stdout); fputc(e[0]+'0',stdout); fputc('.',stdout);
    for (p = 0; p < P; ++p)
    {
        e[0] = 0;
        multiply(e,10,I+X);
        fputc(e[0]+'0',stdout);
        if (p%5 == 4)
            if (p%50 == 49)
                fputs("\n\t",stdout);
            else
                fputc(' ',stdout);
    }
    fputc('\n',stdout);

    return 0;
}

void divide(char *dvd, unsigned dvr, unsigned prc)
{
    char *Wk_q;
    unsigned bit, rmdr;

    rmdr = 0;
    for (Wk_q = dvd; Wk_q < dvd+prc; ++Wk_q)
    {
        for(bit = 0; bit < 8; ++bit)
        {
            rmdr *= 2;
            if (*Wk_q & 0200) rmdr += 1;
            *Wk_q <<= 1;
            if (rmdr >= dvr)
            {
                *Wk_q += 1;
                rmdr -= dvr;
            }
        }
    }
}

void multiply(char *mcd, unsigned mpy, unsigned prc)
{
    char *Wk_r;
    unsigned bit, ovflo;

    ovflo = 0;
    for (Wk_r = mcd+prc-1; Wk_r >= mcd; --Wk_r)
    {
        for (bit = 8; bit > 0; --bit)
        {
            if (*Wk_r & 1) ovflo += mpy;
            *Wk_r >>= 1; *Wk_r &= 0177;
            if (ovflo & 1) *Wk_r = *Wk_r | 0200;
            ovflo /= 2;
        }
    }
}