util-linux/cal.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Calendar implementation for busybox
  *
  * See original copyright at the end of this file
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 /* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
  *
  * Major size reduction... over 50% (>1.5k) on i386.
  */
 //config:config CAL
 //config:	bool "cal (5.8 kb)"
 //config:	default y
 //config:	help
 //config:	cal is used to display a monthly calendar.

 //applet:IF_CAL(APPLET_NOEXEC(cal, cal, BB_DIR_USR_BIN, BB_SUID_DROP, cal))
 /* NOEXEC despite rare cases when it can be a "runner" (e.g. cal -n12000 takes you into years 30xx) */

 //kbuild:lib-$(CONFIG_CAL) += cal.o

 /* BB_AUDIT SUSv3 compliant with -j and -y extensions (from util-linux). */
 /* BB_AUDIT BUG: The output of 'cal -j 1752' is incorrect.  The upstream
  * BB_AUDIT BUG: version in util-linux seems to be broken as well. */
 /* http://www.opengroup.org/onlinepubs/007904975/utilities/cal.html */

 //usage:#define cal_trivial_usage
 //usage:       "[-jy] [[MONTH] YEAR]"
 //usage:#define cal_full_usage "\n\n"
 //usage:       "Display a calendar\n"
 //usage:     "\n	-j	Use julian dates"
 //usage:     "\n	-y	Display the entire year"

 #include "libbb.h"
 #include "unicode.h"

 /* We often use "unsigned" instead of "int", it's easier to div on most CPUs */

 #define	THURSDAY		4		/* for reformation */
 #define	SATURDAY		6		/* 1 Jan 1 was a Saturday */

 #define	FIRST_MISSING_DAY	639787		/* 3 Sep 1752 */
 #define	NUMBER_MISSING_DAYS	11		/* 11 day correction */

 #define	MAXDAYS			42		/* max slots in a month array */
 #define	SPACE			-1		/* used in day array */

 static const unsigned char days_in_month[] ALIGN1 = {
 	0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
 };

 static const unsigned char sep1752[] ALIGN1 = {
 		1,	2,	14,	15,	16,
 	17,	18,	19,	20,	21,	22,	23,
 	24,	25,	26,	27,	28,	29,	30
 };

 /* Set to 0 or 1 in main */
 #define julian ((unsigned)option_mask32)

 /* leap year -- account for Gregorian reformation in 1752 */
 static int leap_year(unsigned yr)
 {
 	if (yr <= 1752)
 		return !(yr % 4);
 	return (!(yr % 4) && (yr % 100)) || !(yr % 400);
 }

 /* number of centuries since 1700, not inclusive */
 #define	centuries_since_1700(yr) \
 	((yr) > 1700 ? (yr) / 100 - 17 : 0)

 /* number of centuries since 1700 whose modulo of 400 is 0 */
 #define	quad_centuries_since_1700(yr) \
 	((yr) > 1600 ? ((yr) - 1600) / 400 : 0)

 /* number of leap years between year 1 and this year, not inclusive */
 #define	leap_years_since_year_1(yr) \
 	((yr) / 4 - centuries_since_1700(yr) + quad_centuries_since_1700(yr))

 static void center(char *, unsigned, unsigned);
 static void day_array(unsigned, unsigned, unsigned *);
 static void trim_trailing_spaces_and_print(char *);

 static void blank_string(char *buf, size_t buflen);
 static char *build_row(char *p, unsigned *dp);

 #define	DAY_LEN		3		/* 3 spaces per day */
 #define	J_DAY_LEN	(DAY_LEN + 1)
 #define	WEEK_LEN	20		/* 7 * 3 - one space at the end */
 #define	J_WEEK_LEN	(WEEK_LEN + 7)
 #define	HEAD_SEP	2		/* spaces between day headings */

 int cal_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int cal_main(int argc UNUSED_PARAM, char **argv)
 {
 	struct tm zero_tm;
 	time_t now;
 	unsigned month, year, flags, i;
 	char *month_names[12];
 	/* normal heading: */
 	/* "Su Mo Tu We Th Fr Sa" */
 	/* -j heading: */
 	/* " Su  Mo  Tu  We  Th  Fr  Sa" */
 	char day_headings[ENABLE_UNICODE_SUPPORT ? 28 * 6 : 28];
 	IF_UNICODE_SUPPORT(char *hp = day_headings;)
 	char buf[40];

 	init_unicode();

 	flags = getopt32(argv, "jy");
 	/* This sets julian = flags & 1: */
 	option_mask32 &= 1;
 	month = 0;
 	argv += optind;

 	if (!argv[0]) {
 		struct tm *ptm;

 		time(&now);
 		ptm = localtime(&now);
 		year = ptm->tm_year + 1900;
 		if (!(flags & 2)) { /* no -y */
 			month = ptm->tm_mon + 1;
 		}
 	} else {
 		if (argv[1]) {
 			if (argv[2]) {
 				bb_show_usage();
 			}
 			if (!(flags & 2)) { /* no -y */
 				month = xatou_range(*argv, 1, 12);
 			}
 			argv++;
 		}
 		year = xatou_range(*argv, 1, 9999);
 	}

 	blank_string(day_headings, sizeof(day_headings) - 7 + 7*julian);

 	i = 0;
 	do {
 		zero_tm.tm_mon = i;
 		/* full month name according to locale */
 		strftime(buf, sizeof(buf), "%B", &zero_tm);
 		month_names[i] = xstrdup(buf);

 		if (i < 7) {
 			zero_tm.tm_wday = i;
 			/* abbreviated weekday name according to locale */
 			strftime(buf, sizeof(buf), "%a", &zero_tm);
 #if ENABLE_UNICODE_SUPPORT
 			if (julian)
 				*hp++ = ' ';
 			{
 				char *two_wchars = unicode_conv_to_printable_fixedwidth(/*NULL,*/ buf, 2);
 				strcpy(hp, two_wchars);
 				free(two_wchars);
 			}
 			hp += strlen(hp);
 			*hp++ = ' ';
 #else
 			strncpy(day_headings + i * (3+julian) + julian, buf, 2);
 #endif
 		}
 	} while (++i < 12);
 	IF_UNICODE_SUPPORT(hp[-1] = '\0';)

 	if (month) {
 		unsigned row, len, days[MAXDAYS];
 		unsigned *dp = days;
 		char lineout[30];

 		day_array(month, year, dp);
 		len = sprintf(lineout, "%s %u", month_names[month - 1], year);
 		printf("%*s%s\n%s\n",
 				((7*julian + WEEK_LEN) - len) / 2, "",
 				lineout, day_headings);
 		for (row = 0; row < 6; row++) {
 			build_row(lineout, dp)[0] = '\0';
 			dp += 7;
 			trim_trailing_spaces_and_print(lineout);
 		}
 	} else {
 		unsigned row, which_cal, week_len, days[12][MAXDAYS];
 		unsigned *dp;
 		char lineout[80];

 		sprintf(lineout, "%u", year);
 		center(lineout,
 				(WEEK_LEN * 3 + HEAD_SEP * 2)
 				+ julian * (J_WEEK_LEN * 2 + HEAD_SEP
 						- (WEEK_LEN * 3 + HEAD_SEP * 2)),
 				0
 		);
 		puts("\n");		/* two \n's */
 		for (i = 0; i < 12; i++) {
 			day_array(i + 1, year, days[i]);
 		}
 		blank_string(lineout, sizeof(lineout));
 		week_len = WEEK_LEN + julian * (J_WEEK_LEN - WEEK_LEN);
 		for (month = 0; month < 12; month += 3-julian) {
 			center(month_names[month], week_len, HEAD_SEP);
 			if (!julian) {
 				center(month_names[month + 1], week_len, HEAD_SEP);
 			}
 			center(month_names[month + 2 - julian], week_len, 0);
 			printf("\n%s%*s%s", day_headings, HEAD_SEP, "", day_headings);
 			if (!julian) {
 				printf("%*s%s", HEAD_SEP, "", day_headings);
 			}
 			bb_putchar('\n');
 			for (row = 0; row < (6*7); row += 7) {
 				for (which_cal = 0; which_cal < 3-julian; which_cal++) {
 					dp = days[month + which_cal] + row;
 					build_row(lineout + which_cal * (week_len + 2), dp);
 				}
 				/* blank_string took care of nul termination. */
 				trim_trailing_spaces_and_print(lineout);
 			}
 		}
 	}

 	fflush_stdout_and_exit(EXIT_SUCCESS);
 }

 /*
  * day_array --
  *	Fill in an array of 42 integers with a calendar.  Assume for a moment
  *	that you took the (maximum) 6 rows in a calendar and stretched them
  *	out end to end.  You would have 42 numbers or spaces.  This routine
  *	builds that array for any month from Jan. 1 through Dec. 9999.
  */
 static void day_array(unsigned month, unsigned year, unsigned *days)
 {
 	unsigned long temp;
 	unsigned i;
 	unsigned day, dw, dm;

 	memset(days, SPACE, MAXDAYS * sizeof(int));

 	if ((month == 9) && (year == 1752)) {
 		/* Assumes the Gregorian reformation eliminates
 		 * 3 Sep. 1752 through 13 Sep. 1752.
 		 */
 		unsigned j_offset = julian * 244;
 		size_t oday = 0;

 		do {
 			days[oday+2] = sep1752[oday] + j_offset;
 		} while (++oday < sizeof(sep1752));

 		return;
 	}

 	/* day_in_year
 	 * return the 1 based day number within the year
 	 */
 	day = 1;
 	if ((month > 2) && leap_year(year)) {
 		++day;
 	}

 	i = month;
 	while (i) {
 		day += days_in_month[--i];
 	}

 	/* day_in_week
 	 * return the 0 based day number for any date from 1 Jan. 1 to
 	 * 31 Dec. 9999.  Assumes the Gregorian reformation eliminates
 	 * 3 Sep. 1752 through 13 Sep. 1752.  Returns Thursday for all
 	 * missing days.
 	 */
 	temp = (long)(year - 1) * 365 + leap_years_since_year_1(year - 1) + day;
 	if (temp < FIRST_MISSING_DAY) {
 		dw = ((temp - 1 + SATURDAY) % 7);
 	} else {
 		dw = (((temp - 1 + SATURDAY) - NUMBER_MISSING_DAYS) % 7);
 	}

 	if (!julian) {
 		day = 1;
 	}

 	dm = days_in_month[month];
 	if ((month == 2) && leap_year(year)) {
 		++dm;
 	}

 	do {
 		days[dw++] = day++;
 	} while (--dm);
 }

 static void trim_trailing_spaces_and_print(char *s)
 {
 	char *p = s;

 	while (*p) {
 		++p;
 	}
 	while (p != s) {
 		--p;
 		if (!isspace(*p)) {
 			p[1] = '\0';
 			break;
 		}
 	}

 	puts(s);
 }

 static void center(char *str, unsigned len, unsigned separate)
 {
 	unsigned n = strlen(str);
 	len -= n;
 	printf("%*s%*s", (len/2) + n, str, (len/2) + (len % 2) + separate, "");
 }

 static void blank_string(char *buf, size_t buflen)
 {
 	memset(buf, ' ', buflen);
 	buf[buflen-1] = '\0';
 }

 static char *build_row(char *p, unsigned *dp)
 {
 	unsigned col, val, day;

 	memset(p, ' ', (julian + DAY_LEN) * 7);

 	col = 0;
 	do {
 		day = *dp++;
 		if (day != SPACE) {
 			if (julian) {
 				++p;
 				if (day >= 100) {
 					*p = '0';
 					p[-1] = (day / 100) + '0';
 					day %= 100;
 				}
 			}
 			val = day / 10;
 			if (val > 0) {
 				*p = val + '0';
 			}
 			*++p = day % 10 + '0';
 			p += 2;
 		} else {
 			p += DAY_LEN + julian;
 		}
 	} while (++col < 7);

 	return p;
 }

 /*
  * Copyright (c) 1989, 1993, 1994
  *	The Regents of the University of California.  All rights reserved.
  *
  * This code is derived from software contributed to Berkeley by
  * Kim Letkeman.
  *
  * 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. 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.
  */
	/* vi: set sw=4 ts=4: */
	/*
	* Calendar implementation for busybox
	*
	* See original copyright at the end of this file
	*
	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
	*/
	/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
	*
	* Major size reduction... over 50% (>1.5k) on i386.
	*/
	//config:config CAL
	//config: bool "cal (5.8 kb)"
	//config: default y
	//config: help
	//config: cal is used to display a monthly calendar.

	//applet:IF_CAL(APPLET_NOEXEC(cal, cal, BB_DIR_USR_BIN, BB_SUID_DROP, cal))
	/* NOEXEC despite rare cases when it can be a "runner" (e.g. cal -n12000 takes you into years 30xx) */

	//kbuild:lib-$(CONFIG_CAL) += cal.o

	/* BB_AUDIT SUSv3 compliant with -j and -y extensions (from util-linux). */
	/* BB_AUDIT BUG: The output of 'cal -j 1752' is incorrect. The upstream
	* BB_AUDIT BUG: version in util-linux seems to be broken as well. */
	/* http://www.opengroup.org/onlinepubs/007904975/utilities/cal.html */

	//usage:#define cal_trivial_usage
	//usage: "[-jy] [[MONTH] YEAR]"
	//usage:#define cal_full_usage "\n\n"
	//usage: "Display a calendar\n"
	//usage: "\n -j Use julian dates"
	//usage: "\n -y Display the entire year"

	#include "libbb.h"
	#include "unicode.h"

	/* We often use "unsigned" instead of "int", it's easier to div on most CPUs */

	#define THURSDAY 4 /* for reformation */
	#define SATURDAY 6 /* 1 Jan 1 was a Saturday */

	#define FIRST_MISSING_DAY 639787 /* 3 Sep 1752 */
	#define NUMBER_MISSING_DAYS 11 /* 11 day correction */

	#define MAXDAYS 42 /* max slots in a month array */
	#define SPACE -1 /* used in day array */

	static const unsigned char days_in_month[] ALIGN1 = {
	0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
	};

	static const unsigned char sep1752[] ALIGN1 = {
	1, 2, 14, 15, 16,
	17, 18, 19, 20, 21, 22, 23,
	24, 25, 26, 27, 28, 29, 30
	};

	/* Set to 0 or 1 in main */
	#define julian ((unsigned)option_mask32)

	/* leap year -- account for Gregorian reformation in 1752 */
	static int leap_year(unsigned yr)
	{
	if (yr <= 1752)
	return !(yr % 4);
	return (!(yr % 4) && (yr % 100)) \|\| !(yr % 400);
	}

	/* number of centuries since 1700, not inclusive */
	#define centuries_since_1700(yr) \
	((yr) > 1700 ? (yr) / 100 - 17 : 0)

	/* number of centuries since 1700 whose modulo of 400 is 0 */
	#define quad_centuries_since_1700(yr) \
	((yr) > 1600 ? ((yr) - 1600) / 400 : 0)

	/* number of leap years between year 1 and this year, not inclusive */
	#define leap_years_since_year_1(yr) \
	((yr) / 4 - centuries_since_1700(yr) + quad_centuries_since_1700(yr))

	static void center(char *, unsigned, unsigned);
	static void day_array(unsigned, unsigned, unsigned *);
	static void trim_trailing_spaces_and_print(char *);

	static void blank_string(char *buf, size_t buflen);
	static char build_row(char p, unsigned *dp);

	#define DAY_LEN 3 /* 3 spaces per day */
	#define J_DAY_LEN (DAY_LEN + 1)
	#define WEEK_LEN 20 /* 7 * 3 - one space at the end */
	#define J_WEEK_LEN (WEEK_LEN + 7)
	#define HEAD_SEP 2 /* spaces between day headings */

	int cal_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
	int cal_main(int argc UNUSED_PARAM, char **argv)
	{
	struct tm zero_tm;
	time_t now;
	unsigned month, year, flags, i;
	char *month_names[12];
	/* normal heading: */
	/* "Su Mo Tu We Th Fr Sa" */
	/* -j heading: */
	/* " Su Mo Tu We Th Fr Sa" */
	char day_headings[ENABLE_UNICODE_SUPPORT ? 28 * 6 : 28];
	IF_UNICODE_SUPPORT(char *hp = day_headings;)
	char buf[40];

	init_unicode();

	flags = getopt32(argv, "jy");
	/* This sets julian = flags & 1: */
	option_mask32 &= 1;
	month = 0;
	argv += optind;

	if (!argv[0]) {
	struct tm *ptm;

	time(&now);
	ptm = localtime(&now);
	year = ptm->tm_year + 1900;
	if (!(flags & 2)) { /* no -y */
	month = ptm->tm_mon + 1;
	}
	} else {
	if (argv[1]) {
	if (argv[2]) {
	bb_show_usage();
	}
	if (!(flags & 2)) { /* no -y */
	month = xatou_range(*argv, 1, 12);
	}
	argv++;
	}
	year = xatou_range(*argv, 1, 9999);
	}

	blank_string(day_headings, sizeof(day_headings) - 7 + 7*julian);

	i = 0;
	do {
	zero_tm.tm_mon = i;
	/* full month name according to locale */
	strftime(buf, sizeof(buf), "%B", &zero_tm);
	month_names[i] = xstrdup(buf);

	if (i < 7) {
	zero_tm.tm_wday = i;
	/* abbreviated weekday name according to locale */
	strftime(buf, sizeof(buf), "%a", &zero_tm);
	#if ENABLE_UNICODE_SUPPORT
	if (julian)
	*hp++ = ' ';
	{
	char two_wchars = unicode_conv_to_printable_fixedwidth(/NULL,*/ buf, 2);
	strcpy(hp, two_wchars);
	free(two_wchars);
	}
	hp += strlen(hp);
	*hp++ = ' ';
	#else
	strncpy(day_headings + i * (3+julian) + julian, buf, 2);
	#endif
	}
	} while (++i < 12);
	IF_UNICODE_SUPPORT(hp[-1] = '\0';)

	if (month) {
	unsigned row, len, days[MAXDAYS];
	unsigned *dp = days;
	char lineout[30];

	day_array(month, year, dp);
	len = sprintf(lineout, "%s %u", month_names[month - 1], year);
	printf("%*s%s\n%s\n",
	((7*julian + WEEK_LEN) - len) / 2, "",
	lineout, day_headings);
	for (row = 0; row < 6; row++) {
	build_row(lineout, dp)[0] = '\0';
	dp += 7;
	trim_trailing_spaces_and_print(lineout);
	}
	} else {
	unsigned row, which_cal, week_len, days[12][MAXDAYS];
	unsigned *dp;
	char lineout[80];

	sprintf(lineout, "%u", year);
	center(lineout,
	(WEEK_LEN * 3 + HEAD_SEP * 2)
	+ julian * (J_WEEK_LEN * 2 + HEAD_SEP
	- (WEEK_LEN * 3 + HEAD_SEP * 2)),
	0
	);
	puts("\n"); /* two \n's */
	for (i = 0; i < 12; i++) {
	day_array(i + 1, year, days[i]);
	}
	blank_string(lineout, sizeof(lineout));
	week_len = WEEK_LEN + julian * (J_WEEK_LEN - WEEK_LEN);
	for (month = 0; month < 12; month += 3-julian) {
	center(month_names[month], week_len, HEAD_SEP);
	if (!julian) {
	center(month_names[month + 1], week_len, HEAD_SEP);
	}
	center(month_names[month + 2 - julian], week_len, 0);
	printf("\n%s%*s%s", day_headings, HEAD_SEP, "", day_headings);
	if (!julian) {
	printf("%*s%s", HEAD_SEP, "", day_headings);
	}
	bb_putchar('\n');
	for (row = 0; row < (6*7); row += 7) {
	for (which_cal = 0; which_cal < 3-julian; which_cal++) {
	dp = days[month + which_cal] + row;
	build_row(lineout + which_cal * (week_len + 2), dp);
	}
	/* blank_string took care of nul termination. */
	trim_trailing_spaces_and_print(lineout);
	}
	}
	}

	fflush_stdout_and_exit(EXIT_SUCCESS);
	}

	/*
	* day_array --
	* Fill in an array of 42 integers with a calendar. Assume for a moment
	* that you took the (maximum) 6 rows in a calendar and stretched them
	* out end to end. You would have 42 numbers or spaces. This routine
	* builds that array for any month from Jan. 1 through Dec. 9999.
	*/
	static void day_array(unsigned month, unsigned year, unsigned *days)
	{
	unsigned long temp;
	unsigned i;
	unsigned day, dw, dm;

	memset(days, SPACE, MAXDAYS * sizeof(int));

	if ((month == 9) && (year == 1752)) {
	/* Assumes the Gregorian reformation eliminates
	* 3 Sep. 1752 through 13 Sep. 1752.
	*/
	unsigned j_offset = julian * 244;
	size_t oday = 0;

	do {
	days[oday+2] = sep1752[oday] + j_offset;
	} while (++oday < sizeof(sep1752));

	return;
	}

	/* day_in_year
	* return the 1 based day number within the year
	*/
	day = 1;
	if ((month > 2) && leap_year(year)) {
	++day;
	}

	i = month;
	while (i) {
	day += days_in_month[--i];
	}

	/* day_in_week
	* return the 0 based day number for any date from 1 Jan. 1 to
	* 31 Dec. 9999. Assumes the Gregorian reformation eliminates
	* 3 Sep. 1752 through 13 Sep. 1752. Returns Thursday for all
	* missing days.
	*/
	temp = (long)(year - 1) * 365 + leap_years_since_year_1(year - 1) + day;
	if (temp < FIRST_MISSING_DAY) {
	dw = ((temp - 1 + SATURDAY) % 7);
	} else {
	dw = (((temp - 1 + SATURDAY) - NUMBER_MISSING_DAYS) % 7);
	}

	if (!julian) {
	day = 1;
	}

	dm = days_in_month[month];
	if ((month == 2) && leap_year(year)) {
	++dm;
	}

	do {
	days[dw++] = day++;
	} while (--dm);
	}

	static void trim_trailing_spaces_and_print(char *s)
	{
	char *p = s;

	while (*p) {
	++p;
	}
	while (p != s) {
	--p;
	if (!isspace(*p)) {
	p[1] = '\0';
	break;
	}
	}

	puts(s);
	}

	static void center(char *str, unsigned len, unsigned separate)
	{
	unsigned n = strlen(str);
	len -= n;
	printf("%s%s", (len/2) + n, str, (len/2) + (len % 2) + separate, "");
	}

	static void blank_string(char *buf, size_t buflen)
	{
	memset(buf, ' ', buflen);
	buf[buflen-1] = '\0';
	}

	static char build_row(char p, unsigned *dp)
	{
	unsigned col, val, day;

	memset(p, ' ', (julian + DAY_LEN) * 7);

	col = 0;
	do {
	day = *dp++;
	if (day != SPACE) {
	if (julian) {
	++p;
	if (day >= 100) {
	*p = '0';
	p[-1] = (day / 100) + '0';
	day %= 100;
	}
	}
	val = day / 10;
	if (val > 0) {
	*p = val + '0';
	}
	*++p = day % 10 + '0';
	p += 2;
	} else {
	p += DAY_LEN + julian;
	}
	} while (++col < 7);

	return p;
	}

	/*
	* Copyright (c) 1989, 1993, 1994
	* The Regents of the University of California. All rights reserved.
	*
	* This code is derived from software contributed to Berkeley by
	* Kim Letkeman.
	*
	* 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. 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.
	*/