/*
 * intcnv.c - convert integer into various forms
 */
/*-
 * Copyright (c) 2008-2019
 *	Jeffrey Allen Neitzel <jan (at) etsh (dot) nl>.
 *	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.
 *
 * THIS SOFTWARE IS PROVIDED BY JEFFREY ALLEN NEITZEL ``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 JEFFREY ALLEN NEITZEL 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.
 *
 *	@(#)$Id: intcnv.c,v 1.1.1.1 2019/04/30 01:12:17 jneitzel Exp $
 */

#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifndef	lint
#ifndef	INTCNV_ATTR
# if __GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 4
#  define	INTCNV_ATTR	__attribute__((__used__))
# elif defined(__GNUC__)
#  define	INTCNV_ATTR	__attribute__((__unused__))
# else
#  define	INTCNV_ATTR	/* nothing */
# endif
#endif	/* !INTCNV_ATTR */

/*@unused@*/
static const char *const vcid[] INTCNV_ATTR = {
	"\100(#)\044Id: intcnv-current \044",
	"\100(#)\044Id: Copyright (c) 2008-2019 Jeffrey Allen Neitzel. \044"
};
#endif	/* !lint */

#define	MYNAME	"unknown"
#define	BITMAX	(sizeof(int) * CHAR_BIT)
#define	BUFMAX	(BITMAX + 1)

/*@observer@*/
static	const char	*myname = NULL;

static	void	setmyname(/*@null@*/ const char *);
static	bool	xstrtonum(int *, const char *, int);
static	char	*numtobin(/*@out@*/ /*@returned@*/ char *, int, size_t);
static	int	getbitval(unsigned, unsigned);
static	void	writeout(const char *, int);

/*
 * NAME
 *	intcnv - convert integer into various forms
 *
 * SYNOPSIS
 *	intcnv [-b] integer
 *
 * DESCRIPTION
 *	See the intcnv(1) manual page for full details.
 */
int
main(int argc, char **argv)
{
	int num = 0;
	char buf[BUFMAX];
	bool bflag = false;

	setmyname(argv[0]);

	if (argc > 1 && strcmp(argv[1], "-b") == 0) {
		bflag = true;
		argc--;
		argv++;
	}
	if (argc != 2) {
		(void)fprintf(stderr, "usage: %s [-b] integer\n", myname);
		return 1;
	}

	if (!xstrtonum(&num, argv[1], bflag ? 2 : 0))
		return 1;

	writeout(numtobin(buf, num, sizeof(buf)), num);

	return 0;
}

/*
 * Set the global myname to the basename of the string pointed to by s.
 */
static void
setmyname(const char *s)
{
	const char *p;

	if (s != NULL && *s != '\0') {
		if ((p = strrchr(s, '/')) != NULL)
			p++;
		else
			p = s;
	} else
		/* should never (but can) be true */
		p = MYNAME;

	myname = p;
}

/*
 * According to base b (2 for base-2 or 0 for base-(8|10|16)), convert
 * the string pointed to by s into a number pointed to by integer n.
 * Return true on success.  Return false on error.
 */
static bool
xstrtonum(int *n, const char *s, int b)
{
	long num;
	char *nbad;

	errno = 0;
	num = strtol(s, &nbad, b);
	if (*s == '\0' || *nbad != '\0') {
		(void)fprintf(stderr, "%s: %s: Invalid integer\n", myname, s);
		*n = 0;
		return false;
	}
	/* From: EXAMPLES section of NetBSD strtol(3) (see LICENSE) */
	if ((errno == ERANGE  && (num == LONG_MAX || num == LONG_MIN)) ||
	    (num   >  INT_MAX ||  num <  INT_MIN)) {
		(void)fprintf(stderr, "%s: %s: Out of range\n", myname, s);
		*n = 0;
		return false;
	}

	*n = (int)num;
	return true;
}

/*
 * Convert the number num into its binary form, copy it to buf,
 * and return a pointer it.
 */
static char *
numtobin(char *buf, int num, size_t siz)
{
	int bps;
	char *b;

	*buf = '\0';
	for (b=buf, bps=(int)BITMAX-1; b < &buf[siz] && bps >= 0; b++, bps--)
		*b = getbitval((unsigned)num, (unsigned)bps);
	*b = '\0';

	return buf;
}

/*
 * Get the bit value in integer n at bit position b.
 * Return the '0' or '1' character on success.
 * Return -1 on error.
 */
static int
getbitval(unsigned n, unsigned b)
{

	if (b >= (unsigned)BITMAX)	/* should never be true */
		return -1;

	return ((n & (1U << b)) == 0) ? '0' : '1';
}

/*
 * Write the conversion results to the standard output stream.
 */
static void
writeout(const char *b, int n)
{

	(void)printf("     Binary:  %s\n"  , b);
	(void)printf("      Octal:  0%o\n" , /*(unsigned)*/n);
	(void)printf("    Decimal: % d\n"  , n);
	(void)printf("Hexadecimal:  0x%X\n", /*(unsigned)*/n);
}