usr/src/usr.bin/f77/libI77/fmtlib.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *      @(#)fmtlib.c    5.1     %G%
 */

/*
 * integer to ascii conversion
 *
 * This code has been rearranged to produce optimized runtime code.
 */

#include "fio.h"

static char     _digit[] = "0123456789abcdefghijklmnopqrstuvwxyz";
static char     _icv_buf[MAXINTLENGTH+1];
#define         _mask   0x7fffffff

char *
icvt(value, ndigit, sign)
long    value;
int     *ndigit;
int     *sign;
{
        register long   val = value;
        register long   rad = radix;
        register char   *b = &_icv_buf[MAXINTLENGTH];
        register char   *d = _digit;
        register long   tmp1;
        register int    tmp2;
        long    rem;
        long    kludge;

        if (val == 0)
        {
                *--b = '0';
                *sign = 0;
                *ndigit = 1;
                return(b);
        }

        if (signit && (*sign = (val < 0)))      /* signed conversion */
        {
                /*
                 * It is necessary to do the first divide
                 * before the absolute value, for the case -2^31
                 *
                 * This is actually what is being done...
                 * tmp1 = (int)(val % rad);
                 * val /= rad;
                 * val = -val
                 * *--b = d[-tmp1];
                 */
                tmp1 = val / rad;
                *--b = d[(tmp1 * rad) - val];
                val = -tmp1;
        }
        else                            /* unsigned conversion */
        {
                *sign = 0;
                if (val < 0)
                {       /* ALL THIS IS TO SIMULATE UNSIGNED LONG MOD & DIV */
                        kludge = _mask - (rad - 1);
                        val &= _mask;
                        /*
                         * This is really what's being done...
                         * rem = (kludge % rad) + (val % rad);
                         * val = (kludge / rad) + (val / rad) + (rem / rad) + 1;
                         * *--b = d[rem % rad];
                         */
                        tmp1 = kludge / rad;
                        tmp2 = val / rad;
                        rem = (kludge - (tmp1 * rad)) + (val - (tmp2 * rad));
                        val = ++tmp1 + tmp2;
                        tmp1 = rem / rad;
                        val += tmp1;
                        *--b = d[rem - (tmp1 * rad)];
                }
        }

        while (val)
        {
                /*
                 * This is really what's being done ...
                 * *--b = d[val % rad];
                 * val /= rad;
                 */
                tmp1 = val / rad;
                *--b = d[val - (tmp1 * rad)];
                val = tmp1;
        }

        *ndigit = (&_icv_buf[MAXINTLENGTH] - b);
        return(b);
}