/*
   =============================================================================
	testcio.c -- test how the C I/O functions handle writes and seeks
	Version 7 -- 1987-10-19 -- D.N. Lynx Crowe
   =============================================================================
*/

#define	LATTICEC	1	/* non-zero for Lattice C */

#include "stdio.h"
#include "stddefs.h"
#include "errno.h"

#define	THEFILE		"testcio.tmp"	/* file name */

#if	LATTICEC
#define	fopenb(x,y)	fopen(x,y)
#define	THEMODE		"wb+"		/* file open mode */
#define	MAGIC		0x0000FEDC	/* our MAGIC number */
#else
#define	MAGIC		0xFEDC		/* our MAGIC number */
#define	THEMODE		"w+"		/* file open mode */
#endif

#define	AMOUNT		2400		/* a little bigger than a cluster */

extern	int	errno;			/* the most recent system error code */

FILE *fp1;				/* our file pointer */

/* 
*/

int
getw(stream)
register FILE *stream;
{
	int temp;
	register char *t;

	temp = 0;

#if	LATTICEC
	t = (char *)&temp + 2;
#else
	t = (char *)&temp;
#endif

	*t++ = getc(stream);

	if (ferror(stream))
		return(EOF);

	*t = getc(stream);

	return(temp & 0xFFFF);
}

#if	LATTICEC
void
#endif
putw(w, stream)
register unsigned w;
FILE *stream;
{
	putc(((w >> 8) & 0xFF), stream);

	if (ferror(stream))
		return;

	putc((w & 0xFF), stream);
}

/* 
*/

main()
{
	int i, j, errs;
	long where, was, after;

	/* open the file for write update */

	if (NULL EQ (fp1 = fopenb(THEFILE, THEMODE))) {

		printf("ERROR:  unable to open [%s] in \042%s\042 mode.\n",
			THEFILE, THEMODE);
		exit(1);
	}

	printf("File [%s] open in \042%s\042 mode.\n", THEFILE, THEMODE);

	/* now write some data to it */

	for (i = 0; i < AMOUNT; i++) {

		putw(i, fp1);

		if (ferror(fp1)) {

			printf("ERROR:  write %d failed.  errno = %d.\n",
				i, errno);
			exit(1);
		}
	}

	fflush(fp1);		/* flush the buffer */

	printf("%d words written to file.\n", AMOUNT);
	after = ftell(fp1);
	printf("File position after writing = %ld.\n", after);

	/* seek to the beginning, and read the data back */

	where = 0L;

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	was = ftell(fp1);
	printf("File position after seek to %ld = %ld.\n", where, was);
	printf("Reading back data.\n");
	errs = 0;

	for (i = 0; i < AMOUNT; i++) {

		if (feof(fp1)) {

			printf("ERROR:  unexpected EOF at %d.\n", i);
			exit(1);
		}

		j = getw(fp1);

		if (ferror(fp1)) {

			printf("ERROR:  read error at %d.  errno=%d.\n",
				i, errno);
			exit(1);
		}

		if (i NE j) {

			++errs;
			was = ftell(fp1);
			printf("ERROR:  at %ld, expected %d, read %d.\n",
				was, i, j);
		}
	}

	was = ftell(fp1);
	printf("File written and read back.  File position = %ld.\n", was);
	printf("Read back check complete with %d error%s\n",
		errs, ((errs NE 1) ? "s." : "."));

	if (feof(fp1)) {

		printf("Note:  EOF seen at end of read to EOF.\n");
	
		if (ferror(fp1)) {

			printf("ERROR:  ferror() returned non-zero at EOF.  errno = %d\n",
				errno);
			exit(1);
		}
	}

	if (after EQ was)
		printf("File positions at end of read and write match.\n");
	else {

		printf("File positions at end of read and write differ.\n");
		printf("Write ended at %ld, read ended at %ld.\n",
			after, was);
	}

	/* now get the word at AMOUNT and print it before we write over it */

	where = AMOUNT;

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	if (feof(fp1)) {

		printf("ERROR:  unexpected EOF at %ld after fseek().\n", where);
		exit(1);
	}

	j = getw(fp1);

	if (ferror(fp1)) {

		printf("ERROR:  read error at %ld.  errno=%d.\n",
			where, errno);
		exit(1);
	}

	printf("Random read executed at %ld.  Value read was %d\n", where, j);

	/* now write some data in the middle of the file */

	where = AMOUNT;		/* note that AMOUNT is words, where is bytes */

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	i = MAGIC;

	putw(i, fp1);

	if (ferror(fp1)) {

		printf("ERROR:  write %d failed.  errno = %d.\n",
			i, errno);
		exit(1);
	}

	fflush(fp1);

	printf("Random write of MAGIC executed to %ld.\n", where);

	/* seek back to what we just wrote */

	where = AMOUNT;

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	if (feof(fp1)) {

		printf("ERROR:  unexpected EOF at %ld after fseek().\n", where);
		exit(1);
	}

	j = getw(fp1);

	if (ferror(fp1)) {

		printf("ERROR:  read error at %ld.  errno=%d.\n",
			where, errno);
		exit(1);
	}

	printf("Random access read executed at %ld.\n", where);

	if (j NE MAGIC) {

		printf("ERROR:  j (%d) NE MAGIC (%d).\n", j, MAGIC);
		exit(1);
	}

	if (feof(fp1)) {

		printf("EOF sensed after reading MAGIC at %ld.\n", where);
		exit(1);
	}

	j = getw(fp1);

	if (ferror(fp1)) {

		printf("ERROR:  read error after MAGIC.  errno=%d.\n", errno);
		exit(1);
	}

	printf("Word after MAGIC = %d.\n", j);

	/* seek to the end of the file */

	where = after;

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	if (feof(fp1)) {

		printf("Note:  EOF at %ld after fseek().\n", where);
	}

	/* write the magic word at EOF */

	i = MAGIC;

	putw(i, fp1);

	if (ferror(fp1)) {

		printf("ERROR:  write %d failed.  errno = %d.\n",
			i, errno);
		exit(1);
	}

	printf("Random write of MAGIC executed to %ld.\n", where);

	was = ftell(fp1);
	printf("File position after write at EOF = %ld\n", was);

	fflush(fp1);

	/* seek back to what we just wrote */

	where = after;

	if (fseek(fp1, where, 0)) {

		printf("ERROR:  could not seek to %ld.\n", where);
		exit(1);
	}

	if (feof(fp1)) {

		printf("ERROR:  unexpected EOF at %ld after fseek().\n", where);
		exit(1);
	}

	j = getw(fp1);

	if (ferror(fp1)) {

		printf("ERROR:  read error at %ld.  errno=%d.\n",
			where, errno);
		exit(1);
	}

	printf("Random access read executed at %ld.\n", where);

	if (j NE MAGIC) {

		printf("ERROR:  j (%d) NE MAGIC (%d).\n", j, MAGIC);
		exit(1);
	}

	if (feof(fp1))
		printf("Note:  EOF sensed after reading MAGIC at %ld.\n",
			where);

	was = ftell(fp1);
	printf("Final file position = %ld.\n", was);

	j = getw(fp1);

	if (!feof(fp1)) {

		was = ftell(fp1);
		printf("ERROR:  no EOF seen after read at EOF.  File at %ld.\n",
			was);
		exit(1);
	}

	printf("EOF seen after read at EOF.\n");
	exit(0);
}