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Annotation of 43BSDTahoe/usr.lib/libpc/READ8.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1979 Regents of the University of California */
        !             2: 
        !             3: static char sccsid[] = "@(#)READ8.c 1.9 11/6/83";
        !             4: 
        !             5: #include "h00vars.h"
        !             6: #include <errno.h>
        !             7: extern int errno;
        !             8: 
        !             9: double
        !            10: READ8(curfile)
        !            11:        register struct iorec   *curfile;
        !            12: {
        !            13:        double                  data;
        !            14:        int                     retval;
        !            15: 
        !            16:        if (curfile->funit & FWRITE) {
        !            17:                ERROR("%s: Attempt to read, but open for writing\n",
        !            18:                        curfile->pfname);
        !            19:                return;
        !            20:        }
        !            21:        UNSYNC(curfile);
        !            22:        errno = 0;
        !            23:        retval = readreal(curfile, &data);
        !            24:        if (retval == EOF) {
        !            25:                ERROR("%s: Tried to read past end of file\n", curfile->pfname);
        !            26:                return;
        !            27:        }
        !            28:        if (retval == 0) {
        !            29:                ERROR("%s: Bad data found on real read\n", curfile->pfname);
        !            30:                return;
        !            31:        }
        !            32:        if (errno == ERANGE) {
        !            33:                if (data == 0.0)
        !            34:                        ERROR("%s: Underflow on real read\n", curfile->pfname);
        !            35:                else
        !            36:                        ERROR("%s: Overflow on real read\n", curfile->pfname);
        !            37:                return;
        !            38:        }
        !            39:        if (errno != 0) {
        !            40:                PERROR("Error encountered on real read ", curfile->pfname);
        !            41:                return;
        !            42:        }
        !            43:        return (data);
        !            44: }
        !            45: 
        !            46: /*
        !            47:  *     given a file pointer, read a sequence of characters of the
        !            48:  *     syntax of section 6.1.5 and form them into a double.
        !            49:  *
        !            50:  *     the syntax of a signed-real is:
        !            51:  *         [-|+] digit {digit} [ . digit {digit} ] [ e [+|-] digit {digit} ]
        !            52:  *
        !            53:  *     returns:
        !            54:  *             1       for success (with value in *doublep)
        !            55:  *             0       on error (with *doublep unchanged)
        !            56:  *            -1       on end-of-file during read (with *doublep unchanged)
        !            57:  *     side effects:
        !            58:  *           errno     may be set to ERANGE if atof() sets it.
        !            59:  */
        !            60: readreal(curfile, doublep)
        !            61:        struct iorec    *curfile;
        !            62:        double          *doublep;
        !            63: {
        !            64:        FILE    *filep = curfile->fbuf; /* current file variable */
        !            65:        char    *sequencep;             /* a pointer into sequence */
        !            66:        int     read;                   /* return value from fscanf() */
        !            67:        char    sequence[BUFSIZ];       /* the character sequence */
        !            68:        double  atof();
        !            69: 
        !            70: #define PUSHBACK(curfile, sequencep) \
        !            71:        if (ungetc(*--(sequencep), (curfile)->fbuf) != EOF) { \
        !            72:                *(sequencep) = '\0'; \
        !            73:        } else if ((curfile)->funit & SYNC) { \
        !            74:                (curfile)->funit &= ~SYNC; \
        !            75:                *(curfile)->fileptr = *(sequencep); \
        !            76:                *(sequencep) = '\0'; \
        !            77:        } else { \
        !            78:                return (0); \
        !            79:        }
        !            80: 
        !            81: #define        RETURN_ON_EOF(read) \
        !            82:        if (read == EOF) \
        !            83:                return (EOF); \
        !            84:        else \
        !            85:                /* void */;
        !            86: 
        !            87: #define        PUSH_TO_NULL(sequencep) \
        !            88:        while (*sequencep) \
        !            89:                sequencep++;
        !            90: 
        !            91:        /* general reader of the next character */
        !            92: #define        NEXT_CHAR(read, filep, format, sequencep) \
        !            93:        read = fscanf(filep, "%c", sequencep); \
        !            94:        RETURN_ON_EOF(read); \
        !            95:        *++sequencep = '\0';
        !            96: 
        !            97:        /* e.g. use %[0123456789] for {digit}, and check read */
        !            98: #define        SOME(read, filep, format, sequencep) \
        !            99:        read = fscanf(filep, format, sequencep); \
        !           100:        RETURN_ON_EOF(read); \
        !           101:        PUSH_TO_NULL(sequencep);
        !           102: 
        !           103:        /* e.g. use %[0123456789] for digit {digit} */
        !           104: #define        AT_LEAST_ONE(read, filep, format, sequencep) \
        !           105:        read = fscanf(filep, format, sequencep); \
        !           106:        RETURN_ON_EOF(read); \
        !           107:        if (strlen(sequencep) < 1) \
        !           108:                return (0); \
        !           109:        PUSH_TO_NULL(sequencep);
        !           110: 
        !           111: #define        ANY_ONE_OF(read, filep, format, sequencep) \
        !           112:        read = fscanf(filep, format, sequencep); \
        !           113:        RETURN_ON_EOF(read); \
        !           114:        if (strlen(sequencep) != 1) \
        !           115:                return (0); \
        !           116:        PUSH_TO_NULL(sequencep);
        !           117: 
        !           118: #define        AT_MOST_ONE(read, filep, format, sequencep) \
        !           119:        read = fscanf(filep, format, sequencep); \
        !           120:        RETURN_ON_EOF(read); \
        !           121:        if (strlen(sequencep) > 1) \
        !           122:                return (0); \
        !           123:        PUSH_TO_NULL(sequencep);
        !           124:                
        !           125:        sequencep = &sequence[0];
        !           126:        *sequencep = '\0';
        !           127:        /*
        !           128:         *      skip leading whitespace
        !           129:         */
        !           130:        SOME(read, filep, "%*[ \t\n]", sequencep);
        !           131:        /*
        !           132:         *      this much is required:
        !           133:         *      [ "+" | "-" ] digit {digits}
        !           134:         */
        !           135:        AT_MOST_ONE(read, filep, "%[+-]", sequencep);
        !           136:        AT_LEAST_ONE(read, filep, "%[0123456789]", sequencep);
        !           137:        /*
        !           138:         *      any of this is optional:
        !           139:         *      [ `.' digit {digit} ] [ `e' [ `+' | `-' ] digit {digits} ]
        !           140:         */
        !           141:        NEXT_CHAR(read, filep, "%c", sequencep);
        !           142:        switch (sequencep[-1]) {
        !           143:        default:
        !           144:                PUSHBACK(curfile, sequencep);
        !           145:                goto convert;
        !           146:        case '.':
        !           147:                SOME(read, filep, "%[0123456789]", sequencep);
        !           148:                if (!read) {
        !           149:                        PUSHBACK(curfile, sequencep);
        !           150:                        goto convert;
        !           151:                }
        !           152:                NEXT_CHAR(read, filep, "%c", sequencep);
        !           153:                if (sequencep[-1] != 'e') {
        !           154:                        PUSHBACK(curfile, sequencep);
        !           155:                        goto convert;
        !           156:                }
        !           157:                /* fall through */
        !           158:        case 'e':
        !           159:                NEXT_CHAR(read, filep, "%c", sequencep);
        !           160:                if (sequencep[-1] != '+' && sequencep[-1] != '-') {
        !           161:                        PUSHBACK(curfile, sequencep);
        !           162:                        SOME(read, filep, "%[0123456789]", sequencep);
        !           163:                        if (!read)
        !           164:                                PUSHBACK(curfile, sequencep);
        !           165:                        goto convert;
        !           166:                }
        !           167:                SOME(read, filep, "%[0123456789]", sequencep);
        !           168:                if (!read) {
        !           169:                        PUSHBACK(curfile, sequencep);
        !           170:                        PUSHBACK(curfile, sequencep);
        !           171:                }
        !           172:        }
        !           173: 
        !           174: convert:
        !           175:        /*
        !           176:         * convert sequence to double
        !           177:         */
        !           178:        *doublep = atof(&sequence[0]);
        !           179:        return (1);
        !           180: }

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