xlfio.c

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/* xlfio.c - xlisp file i/o */
/*	Copyright (c) 1985, by David Michael Betz
        All Rights Reserved
        Permission is granted for unrestricted non-commercial use	*/

/* CHANGE LOG
 * --------------------------------------------------------------------
 * 28Apr03  dm  eliminate some compiler warnings
 */


#include "switches.h"

#include <string.h>

#include "xlisp.h"

/* do some sanity checking: */
#ifndef XL_BIG_ENDIAN
#ifndef XL_LITTLE_ENDIAN
configuration error -- either XL_BIG_ or XL_LITTLE_ENDIAN must be defined
in xlisp.h
#endif
#endif
#ifdef XL_BIG_ENDIAN
#ifdef XL_LITTLE_ENDIAN
configuration error -- both XL_BIG_ and XL_LITTLE_ENDIAN are defined!
#endif
#endif

/* forward declarations */
FORWARD LOCAL LVAL getstroutput(LVAL stream);
FORWARD LOCAL LVAL printit(int pflag, int tflag);
FORWARD LOCAL LVAL flatsize(int pflag);

/* xread - read an expression */
LVAL xread(void)
{
    LVAL fptr,eof,rflag,val;

    /* get file pointer and eof value */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    eof = (moreargs() ? xlgetarg() : NIL);
    rflag = (moreargs() ? xlgetarg() : NIL);
    xllastarg();

    /* read an expression */
    if (!xlread(fptr,&val,rflag != NIL))
        val = eof;

    /* return the expression */
    return (val);
}

/* xprint - built-in function 'print' */
LVAL xprint(void)
{
    return (printit(TRUE,TRUE));
}

/* xprin1 - built-in function 'prin1' */
LVAL xprin1(void)
{
    return (printit(TRUE,FALSE));
}

/* xprinc - built-in function princ */
LVAL xprinc(void)
{
    return (printit(FALSE,FALSE));
}

/* xterpri - terminate the current print line */
LVAL xterpri(void)
{
    LVAL fptr;

    /* get file pointer */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdout));
    xllastarg();

    /* terminate the print line and return nil */
    xlterpri(fptr);
    return (NIL);
}

/* printit - common print function */
LOCAL LVAL printit(int pflag, int tflag)
{
    LVAL fptr,val;

    /* get expression to print and file pointer */
    val = xlgetarg();
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdout));
    xllastarg();

    /* print the value */
    xlprint(fptr,val,pflag);

    /* terminate the print line if necessary */
    if (tflag)
        xlterpri(fptr);

    /* return the result */
    return (val);
}

/* xflatsize - compute the size of a printed representation using prin1 */
LVAL xflatsize(void)
{
    return (flatsize(TRUE));
}

/* xflatc - compute the size of a printed representation using princ */
LVAL xflatc(void)
{
    return (flatsize(FALSE));
}

/* flatsize - compute the size of a printed expression */
LOCAL LVAL flatsize(int pflag)
{
    LVAL val;

    /* get the expression */
    val = xlgetarg();
    xllastarg();

    /* print the value to compute its size */
    xlfsize = 0;
    xlprint(NIL,val,pflag);

    /* return the length of the expression */
    return (cvfixnum((FIXTYPE)xlfsize));
}

/* xlopen - open a text or binary file */
LVAL xlopen(int binaryflag)
{
    char *name,*mode=NULL;
    FILE *fp;
    LVAL dir;

    /* get the file name and direction */
    name = (char *)getstring(xlgetfname());
    if (!xlgetkeyarg(k_direction,&dir))
        dir = k_input;

    /* get the mode */
    if (dir == k_input)
        mode = "r";
    else if (dir == k_output)
        mode = "w";
    else
        xlerror("bad direction",dir);

    /* try to open the file */
    if (binaryflag) {
        fp = osbopen(name,mode);
    } else {
        fp = osaopen(name,mode);
    }
    return (fp ? cvfile(fp) : NIL);
}


/* xopen - open a file */
LVAL xopen(void)
{
    return xlopen(FALSE);
}

/* xbopen - open a binary file */
LVAL xbopen(void)
{
        return xlopen(TRUE);
}

/* xclose - close a file */
LVAL xclose(void)
{
    LVAL fptr;

    /* get file pointer */
    fptr = xlgastream();
    xllastarg();

    /* make sure the file exists */
    if (getfile(fptr) == NULL)
        xlfail("file not open");

    /* close the file */
    osclose(getfile(fptr));
    setfile(fptr,NULL);

    /* return nil */
    return (NIL);
}

/* xrdchar - read a character from a file */
LVAL xrdchar(void)
{
    LVAL fptr;
    int ch;

    /* get file pointer */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    xllastarg();

    /* get character and check for eof */
    return ((ch = xlgetc(fptr)) == EOF ? NIL : cvchar(ch));
}

/* xrdint - read an integer from a file */
/* positive byte count means big-endian, negative is little-endian */
LVAL xrdint(void)
{
    LVAL fptr;
    unsigned char b[4];
    long i;
    int n = 4;
    int index = 0; /* where to start in array */
    int incr = 1;  /* how to step through array */
    int rslt;

    /* get file pointer */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    /* get byte count */
    if (moreargs()) {
        LVAL count = typearg(fixp);
        n = getfixnum(count);
        if (n < 0) {
            n = -n;
            index = n - 1;
            incr = -1;
        }
        if (n > 4) {
            xlerror("4-byte limit", count);
        }
    }
    xllastarg();
    for (i = 0; i < n; i++) {
        int ch = xlgetc(fptr);
        if (ch == EOF) return NIL;
        b[index] = ch;
        index += incr;
    }
    /* build result, b is now big-endian */
    /* extend sign bit for short integers */
    rslt = ((b[0] & 0x80) ? -1 : 0);
    for (i = 0; i < n; i++) {
        rslt = (rslt << 8) + b[i];
    }
    /* return integer result */
    return cvfixnum(rslt);
}


/* xrdfloat - read a float from a file */
LVAL xrdfloat(void)
{
    LVAL fptr;
    union {
        char b[8];
        float f;
        double d;
    } rslt;
    int n = 4;
    int i;
    int index = 3;  /* where to start in array */
    int incr = -1;  /* how to step through array */

    /* get file pointer */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    /* get byte count */
    if (moreargs()) {
        LVAL count =  typearg(fixp);
        n = getfixnum(count);
        if (n < 0) {
            n = -n;
            index = 0;
            incr = 1;
        }
        if (n != 4 && n != 8) {
            xlerror("must be 4 or 8 bytes", count);
        }
    }
    xllastarg();

#ifdef XL_BIG_ENDIAN
    /* flip the bytes */
    index = n - 1 - index;
    incr = -incr;
#endif
    for (i = 0; i < n; i++) {
        int ch = xlgetc(fptr);
        if (ch == EOF) return NIL;
        rslt.b[index] = ch;
        index += incr;
    }
    /* return result */
    return cvflonum(n == 4 ? rslt.f : rslt.d);
}


/* xrdbyte - read a byte from a file */
LVAL xrdbyte(void)
{
    LVAL fptr;
    int ch;

    /* get file pointer */
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    xllastarg();

    /* get character and check for eof */
    return ((ch = xlgetc(fptr)) == EOF ? NIL : cvfixnum((FIXTYPE)ch));
}

/* xpkchar - peek at a character from a file */
LVAL xpkchar(void)
{
    LVAL flag,fptr;
    int ch;

    /* peek flag and get file pointer */
    flag = (moreargs() ? xlgetarg() : NIL);
    fptr = (moreargs() ? xlgetfile() : getvalue(s_stdin));
    xllastarg();

    /* skip leading white space and get a character */
    if (flag)
        while ((ch = xlpeek(fptr)) != EOF && isspace(ch))
            xlgetc(fptr);
    else
        ch = xlpeek(fptr);

    /* return the character */
    return (ch == EOF ? NIL : cvchar(ch));
}

/* xwrchar - write a character to a file */
LVAL xwrchar(void)
{
    LVAL fptr,chr;

    /* get the character and file pointer */
    chr = xlgachar();