usr/src/usr.bin/pascal/libpc/READ8.c

/*-
 * Copyright (c) 1979 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)READ8.c     1.11 (Berkeley) 4/9/90";
#endif /* not lint */

#include "h00vars.h"
#include <errno.h>
extern int errno;

double
READ8(curfile)
        register struct iorec   *curfile;
{
        double                  data;
        int                     retval;

        if (curfile->funit & FWRITE) {
                ERROR("%s: Attempt to read, but open for writing\n",
                        curfile->pfname);
        }
        UNSYNC(curfile);
        errno = 0;
        retval = readreal(curfile, &data);
        if (retval == EOF) {
                ERROR("%s: Tried to read past end of file\n", curfile->pfname);
        }
        if (retval == 0) {
                ERROR("%s: Bad data found on real read\n", curfile->pfname);
        }
        if (errno == ERANGE) {
                if (data == 0.0)
                        ERROR("%s: Underflow on real read\n", curfile->pfname);
                else
                        ERROR("%s: Overflow on real read\n", curfile->pfname);
        }
        if (errno != 0) {
                PERROR("Error encountered on real read ", curfile->pfname);
        }
        return (data);
}

/*
 *      given a file pointer, read a sequence of characters of the
 *      syntax of section 6.1.5 and form them into a double.
 *
 *      the syntax of a signed-real is:
 *          [-|+] digit {digit} [ . digit {digit} ] [ e [+|-] digit {digit} ]
 *
 *      returns:
 *              1       for success (with value in *doublep)
 *              0       on error (with *doublep unchanged)
 *             -1       on end-of-file during read (with *doublep unchanged)
 *      side effects:
 *            errno     may be set to ERANGE if atof() sets it.
 */
readreal(curfile, doublep)
        struct iorec    *curfile;
        double          *doublep;
{
        FILE    *filep = curfile->fbuf; /* current file variable */
        char    *sequencep;             /* a pointer into sequence */
        int     read;                   /* return value from fscanf() */
        char    sequence[BUFSIZ];       /* the character sequence */
        double  atof();

#define PUSHBACK(curfile, sequencep) \
        if (ungetc(*--(sequencep), (curfile)->fbuf) != EOF) { \
                *(sequencep) = '\0'; \
        } else if ((curfile)->funit & SYNC) { \
                (curfile)->funit &= ~SYNC; \
                *(curfile)->fileptr = *(sequencep); \
                *(sequencep) = '\0'; \
        } else { \
                return (0); \
        }

#define RETURN_ON_EOF(read) \
        if (read == EOF) \
                return (EOF); \
        else \
                /* void */;

#define PUSH_TO_NULL(sequencep) \
        while (*sequencep) \
                sequencep++;

        /* general reader of the next character */
#define NEXT_CHAR(read, filep, format, sequencep) \
        read = fscanf(filep, "%c", sequencep); \
        RETURN_ON_EOF(read); \
        *++sequencep = '\0';

        /* e.g. use %[0123456789] for {digit}, and check read */
#define SOME(read, filep, format, sequencep) \
        read = fscanf(filep, format, sequencep); \
        RETURN_ON_EOF(read); \
        PUSH_TO_NULL(sequencep);

        /* e.g. use %[0123456789] for digit {digit} */
#define AT_LEAST_ONE(read, filep, format, sequencep) \
        read = fscanf(filep, format, sequencep); \
        RETURN_ON_EOF(read); \
        if (strlen(sequencep) < 1) \
                return (0); \
        PUSH_TO_NULL(sequencep);

#define ANY_ONE_OF(read, filep, format, sequencep) \
        read = fscanf(filep, format, sequencep); \
        RETURN_ON_EOF(read); \
        if (strlen(sequencep) != 1) \
                return (0); \
        PUSH_TO_NULL(sequencep);

#define AT_MOST_ONE(read, filep, format, sequencep) \
        read = fscanf(filep, format, sequencep); \
        RETURN_ON_EOF(read); \
        if (strlen(sequencep) > 1) \
                return (0); \
        PUSH_TO_NULL(sequencep);

        sequencep = &sequence[0];
        *sequencep = '\0';
        /*
         *      skip leading whitespace
         */
        SOME(read, filep, "%*[ \t\n]", sequencep);
        /*
         *      this much is required:
         *      [ "+" | "-" ] digit {digits}
         */
        AT_MOST_ONE(read, filep, "%[+-]", sequencep);
        AT_LEAST_ONE(read, filep, "%[0123456789]", sequencep);
        /*
         *      any of this is optional:
         *      [ `.' digit {digit} ] [ `e' [ `+' | `-' ] digit {digits} ]
         */
        NEXT_CHAR(read, filep, "%c", sequencep);
        switch (sequencep[-1]) {
        default:
                PUSHBACK(curfile, sequencep);
                goto convert;
        case '.':
                SOME(read, filep, "%[0123456789]", sequencep);
                if (!read) {
                        PUSHBACK(curfile, sequencep);
                        goto convert;
                }
                NEXT_CHAR(read, filep, "%c", sequencep);
                if (sequencep[-1] != 'e') {
                        PUSHBACK(curfile, sequencep);
                        goto convert;
                }
                /* fall through */
        case 'e':
                NEXT_CHAR(read, filep, "%c", sequencep);
                if (sequencep[-1] != '+' && sequencep[-1] != '-') {
                        PUSHBACK(curfile, sequencep);
                        SOME(read, filep, "%[0123456789]", sequencep);
                        if (!read)
                                PUSHBACK(curfile, sequencep);
                        goto convert;
                }
                SOME(read, filep, "%[0123456789]", sequencep);
                if (!read) {
                        PUSHBACK(curfile, sequencep);
                        PUSHBACK(curfile, sequencep);
                }
        }

convert:
        /*
         * convert sequence to double
         */
        *doublep = atof(&sequence[0]);
        return (1);
}