Source:NetHack 3.4.3/src/hacklib.c

Below is the full text to src/hacklib.c from NetHack 3.4.3. To link to a particular line, write [[hacklib.c#line123]], for example.

The C functions in hacklib.c are old but still work. (Today's standard C libraries provide better replacements for some of them.) They provide miscellaneous features such as handling character strings and finding the phase of the moon. The setrandom code to seed the random number generator is also here.

Top of file

1.    /*	SCCS Id: @(#)hacklib.c	3.4	2002/12/13	*/
2.    /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
3.    /* Copyright (c) Robert Patrick Rankin, 1991		  */
4.    /* NetHack may be freely redistributed.  See license for details. */

The NetHack General Public License applies to screenshots, source code and other content from NetHack.

This content was modified from the original NetHack source code distribution (by splitting up NetHack content between wiki pages, and possibly further editing). See the page history for a list of who changed it, and on what dates.

5.    
6.    /* We could include only config.h, except for the overlay definitions... */
7.    #include "hack.h"
8.    /*=
9.        Assorted 'small' utility routines.	They're virtually independent of
10.   NetHack, except that rounddiv may call panic().
11.   
12.         return type     routine name    argument type(s)
13.   	boolean		digit		(char)
14.   	boolean		letter		(char)
15.   	char		highc		(char)
16.   	char		lowc		(char)
17.   	char *		lcase		(char *)
18.   	char *		upstart		(char *)
19.   	char *		mungspaces	(char *)
20.   	char *		eos		(char *)
21.   	char *		strkitten	(char *,char)
22.   	char *		s_suffix	(const char *)
23.   	char *		xcrypt		(const char *, char *)
24.   	boolean		onlyspace	(const char *)
25.   	char *		tabexpand	(char *)
26.   	char *		visctrl		(char)
27.   	const char *	ordin		(int)
28.   	char *		sitoa		(int)
29.   	int		sgn		(int)
30.   	int		rounddiv	(long, int)
31.   	int		distmin		(int, int, int, int)
32.   	int		dist2		(int, int, int, int)
33.   	boolean		online2		(int, int)
34.   	boolean		pmatch		(const char *, const char *)
35.   	int		strncmpi	(const char *, const char *, int)
36.   	char *		strstri		(const char *, const char *)
37.   	boolean		fuzzymatch	(const char *,const char *,const char *,boolean)
38.   	void		setrandom	(void)
39.   	int		getyear		(void)
40.   	char *		yymmdd		(time_t)
41.   	long		yyyymmdd	(time_t)
42.   	int		phase_of_the_moon	(void)
43.   	boolean		friday_13th	(void)
44.   	int		night		(void)
45.   	int		midnight	(void)
46.   =*/
47.   #ifdef LINT
48.   # define Static		/* pacify lint */
49.   #else
50.   # define Static static
51.   #endif
52.   

digit

The digit function tests if the character is a digit, any of 0 to 9 in ASCII. If we rewrote NetHack today, we would instead use the isdigit function provided by ANSI C.

53.   #ifdef OVLB
54.   boolean
55.   digit(c)		/* is 'c' a digit? */
56.       char c;
57.   {
58.       return((boolean)('0' <= c && c <= '9'));
59.   }
60.   

letter

The letter function tests if the character is a letter. One would use isalpha, but this letter function has the caveat that @ (which is the character before A) in ASCII counts as a letter, in addition to the uppercase and lowercase letters. Thus most monsters are letters, but punctuation including lizards [[:]] and sea creatures ; are not letters.

61.   boolean
62.   letter(c)		/* is 'c' a letter?  note: '@' classed as letter */
63.       char c;
64.   {
65.       return((boolean)(('@' <= c && c <= 'Z') || ('a' <= c && c <= 'z')));
66.   }
67.   #endif /* OVLB */
68.   

highc

The highc function converts any character to uppercase. It converts 'a' to 'z' into uppercase, but copies any other character. Today we would use toupper in ANSI C.

69.   #ifdef OVL1
70.   char
71.   highc(c)			/* force 'c' into uppercase */
72.       char c;
73.   {
74.       return((char)(('a' <= c && c <= 'z') ? (c & ~040) : c));
75.   }
76.   

lowc

The lowc function converts any character to lowercase, the opposite but not the inverse of highc. Today we would use tolower in ANSI C.

77.   char
78.   lowc(c)			/* force 'c' into lowercase */
79.       char c;
80.   {
81.       return((char)(('A' <= c && c <= 'Z') ? (c | 040) : c));
82.   }
83.   #endif /* OVL1 */
84.   

lcase

The lcase function converts a string buffer to lowercase in place, by overwriting not copying the string. To follow ANSI C, we could rewrite this using isupper and tolower.

85.   #ifdef OVLB
86.   char *
87.   lcase(s)		/* convert a string into all lowercase */
88.       char *s;
89.   {
90.       register char *p;
91.   
92.       for (p = s; *p; p++)
93.   	if ('A' <= *p && *p <= 'Z') *p |= 040;
94.       return s;
95.   }
96.   

The rewritten version would be:

/* not part of hacklib.c */
#include <ctype.h>
char *
lcase(char *s)
{
    char* p;
    for(p = s; *p; p++)
	if (isupper(*p)) *p = tolower(*p);
    return s;
}

The old version works if the character set is ASCII, and might be more efficient if the C compiler does not optimise well. The rewritten version is easier to understand, but there is no reason for us to replace the old lcase function that already does best.

upstart

The upstart function uppercases the first letter of a string buffer in place (by overwriting and not copying). We need this when placing nouns for monsters like "it" and "the newt" at the beginning of a sentence.

97.   char *
98.   upstart(s)		/* convert first character of a string to uppercase */
99.       char *s;
100.  {
101.      if (s) *s = highc(*s);
102.      return s;
103.  }
104.  

The if statement upon line 101 ensures that upstart((char *)0) does not dereference a null pointer. Though it is best to be safe, this check was probably unnecessary because in general we should only pass '\0'-terminated strings to functions like these.

mungspaces

The mungspaces function condenses each group of consecutive spaces or tabs (of a string buffer) into a single space in place (by overwriting and not copying). It also trims the spaces and tabs from the beginning and end of the buffer.

105.  /* remove excess whitespace from a string buffer (in place) */
106.  char *
107.  mungspaces(bp)
108.  char *bp;
109.  {
110.      register char c, *p, *p2;
111.      boolean was_space = TRUE;
112.  
113.      for (p = p2 = bp; (c = *p) != '\0'; p++) {
114.  	if (c == '\t') c = ' ';
115.  	if (c != ' ' || !was_space) *p2++ = c;
116.  	was_space = (c == ' ');
117.      }
118.      if (was_space && p2 > bp) p2--;
119.      *p2 = '\0';
120.      return bp;
121.  }
122.  
123.  #endif /* OVLB */
124.  

To make that code easier to read, here is a pretty version:

/* not part of hacklib.c */
char *
mungspaces(char *bp)
{
    char c, *p, *p2;
    boolean was_space = TRUE; /* trim beginning of string */

    p = p2 = pb;
    while ((c = *p) != '\0') { /* until p is end of string */
	if (c == '\t') c = ' ';
	if (c != ' ' || !was_space) {
	    *p2 = c; /* copy it */
	    p2++;
	}
	was_space = (c == ' ');
	p++;
    }

    if (was_space && p2 > bp) p2--; /* trim end of string */
    *p2 = '\0';
    return bp;
}

The mungspaces function is slightly less safe than the upstart function because mungspaces((char *)0) will dereference the null pointer. However mungspaces("") will work because the p2 > bp prevents us from trying to write a '\0' before the start of the buffer.

eos

Given some string, the eos function returns a pointer to the '\0' that terminates it.

125.  #ifdef OVL0
126.  char *
127.  eos(s)			/* return the end of a string (pointing at '\0') */
128.      register char *s;
129.  {
130.      while (*s) s++;	/* s += strlen(s); */
131.      return s;
132.  }
133.  

As the comment on line 130 shows, one could just do s += strlen(s). Someone must have thought that it was a waste of performance to count the number of times we do s++ as strlen would do. Some C compilers will optimise when they see strlen, but the developers wrote NetHack for older compilers.

strkitten

The strkitten function is a baby version of strcat that has less experience points and a weaker attack; see kitten, cat.

Actually, strkitten concatenates a single character to the end of a string. Like the strcat, the strkitten modifies the string being appended to. This function uses the eos function defined above.

134.  /* strcat(s, {c,'\0'}); */
135.  char *
136.  strkitten(s, c)		/* append a character to a string (in place) */
137.      char *s;
138.      char c;
139.  {
140.      char *p = eos(s);
141.  
142.      *p++ = c;
143.      *p = '\0';
144.      return s;
145.  }
146.  

It is important to not use the strkitten function if your buffer does not have room for one more character!

s_suffix

The s_suffix function converts a string (typically naming a monster) to the possessive form, for example gnome to gnome's. Unlike many of the above function, this one creates a new string instead of modifying the original string in place.

147.  char *
148.  s_suffix(s)		/* return a name converted to possessive */
149.      const char *s;
150.  {
151.      Static char buf[BUFSZ];
152.  
153.      Strcpy(buf, s);
154.      if(!strcmpi(buf, "it"))
155.  	Strcat(buf, "s");
156.      else if(*(eos(buf)-1) == 's')
157.  	Strcat(buf, "'");
158.      else
159.  	Strcat(buf, "'s");
160.      return buf;
161.  }
162.  

From the above code, we determine the following rules:

• it has s appended (as it to its, It to Its)
• names ending in s have apostrophe appended (as "Orcus" to "Orcus'")
• other names have s and apostrophe appended (as the gnome to the gnome's)

Unlike strcpy, this s_suffix function does not take a buffer for the new string as a parameter. Instead, s_suffix places the posessive string in its own static buffer. This has two consequences:

• String longer than BUFSZ-1 would overflow, so we must not use very long names.
• We can have only one possessive noun at each time. This translates the rule that whenever we call pline or any of its variants in pline.c, we can use s_suffix only once, for example "You eat the gnome's brain!" (uhitm.c#line1537) Using a second possessive from a different function like Your or mhis (a macro in you.h) does not count, for example "The gnome's helmet blocks your attack to her head!"

Programmers that use languages with garbage collection (as in Java or Perl) would write s_suffix to dynamically allocate the buffer containing the possessive noun, and not need to later free it.

xcrypt

The xcrypt function decodes the Oracle messages and rumors stored in NetHack's playground. When building NetHack, makedefs hid that information so that players looking in the playground would not become spoiled. Though the cipher is symmetric (so that encoding and decoding use the same function), makedefs has its own copy of the xcrypt function.

You pass the input string as the first argument str and an output buffer as the second argument buf; this is the reverse of the order that you would expect from strcpy and memcpy.

163.  char *
164.  xcrypt(str, buf)	/* trivial text encryption routine (see makedefs) */
165.  const char *str;
166.  char *buf;
167.  {
168.      register const char *p;
169.      register char *q;
170.      register int bitmask;
171.  
172.      for (bitmask = 1, p = str, q = buf; *p; q++) {
173.  	*q = *p++;
174.  	if (*q & (32|64)) *q ^= bitmask;
175.  	if ((bitmask <<= 1) >= 32) bitmask = 1;
176.      }
177.      *q = '\0';
178.      return buf;
179.  }
180.  #endif /* OVL0 */
181.  

As do some other symmetric ciphers, the xcrypt generates a stream of data, then exclusive-ors the generated stream with the ciphertext to decode it (or with the plaintext to encode it). Because xcrypt does not use a secret key to seed a secure random number generator, xcrypt provides only trivial security, though xcrypt does better than ROT13.

onlyspace

The onlyspace function tests if the string contains only spaces and tabs. The mungspaces function would transform such a string to the empty string "".

182.  #ifdef OVL2
183.  boolean
184.  onlyspace(s)		/* is a string entirely whitespace? */
185.      const char *s;
186.  {
187.      for (; *s; s++)
188.  	if (*s != ' ' && *s != '\t') return FALSE;
189.      return TRUE;
190.  }
191.  #endif /* OVL2 */
192.  

tabexpand

The tabexpand function replaces tabs with spaces, as if the tab advanced to the next column and the colums were 8 characters wide. It does this expansion in place. (Actually, it does the expansion in its internal buffer, then copies the result overwriting the input buffer.)

The input buffer sbuf needs to be at least BUFSZ large to keep room for the expansion. The internal buffer char buf[BUFSZ] prevents tabexpand from handling longer expansions.

193.  #ifdef OVLB
194.  char *
195.  tabexpand(sbuf)		/* expand tabs into proper number of spaces */
196.      char *sbuf;
197.  {
198.      char buf[BUFSZ];
199.      register char *bp, *s = sbuf;
200.      register int idx;
201.  
202.      if (!*s) return sbuf;
203.  
204.      /* warning: no bounds checking performed */
205.      for (bp = buf, idx = 0; *s; s++)
206.  	if (*s == '\t') {
207.  	    do *bp++ = ' '; while (++idx % 8);
208.  	} else {
209.  	    *bp++ = *s;
210.  	    idx++;
211.  	}
212.      *bp = 0;
213.      return strcpy(sbuf, buf);
214.  }
215.  

The tabexpand function overflows if the expansion is larger than BUFSZ-1 characters. A string containing only 32 tabs would overflow the buffer when BUFSZ is 256. The comment upon line 204 warns that the function will not check against overflow, even though the programmer knew that buf holds only BUFSZ bytes.

NetHack uses tabexpand when displaying from files that contain tabs.

visctrl

The visctrl character formats an ASCII character as a visible string. Control characters are formatted like ^B by using a caret ^ and a bit flip. (This is exactly how many Unix commands (like cat -v) and Unix editors would display them.) All other characters are copied.

216.  char *
217.  visctrl(c)		/* make a displayable string from a character */
218.      char c;
219.  {
220.      Static char ccc[3];
221.  
222.      c &= 0177;
223.  
224.      ccc[2] = '\0';
225.      if (c < 040) {
226.  	ccc[0] = '^';
227.  	ccc[1] = c | 0100;	/* letter */
228.      } else if (c == 0177) {
229.  	ccc[0] = '^';
230.  	ccc[1] = c & ~0100;	/* '?' */
231.      } else {
232.  	ccc[0] = c;		/* printable character */
233.  	ccc[1] = '\0';
234.      }
235.      return ccc;
236.  }
237.  #endif /* OVLB */
238.  

Input	Output
ASCII control characters from 0 to 31 (octal 0 to 040)	caret and control character plus 64 (octoal 0100) ^@, ^A, ^B ... ^Y, ^Z, ^[, ^\, ^], ^^, ^_
ASCII delete character 127 (octal 0177)	caret and question mark 63 (octal 077) ^?
all other characters, including spaces and characters above 127 (8-bit meta characters)	copied from input

Because visctrl outputs into an internal buffer, we follow the rule of one control character per sentence fragment, similar to the rule for using s_suffix.

The BSD C library provides a function vis that does something similar. Upon BSD (but not most other platforms!), we could rewrite the visctrl function this way:

/* not part of hacklib.c */
#include <vis.h>
char *
visctrl(char c)
{
    static char ccc[3];
    vis(ccc, c, VIS_TAB | VIS_NL | VIS_NOSLASH, 0);
}

The rewritten visctrl also formats meta-characters like M-B.

ordin

The ordin function returns the string constant "st" or "nd" or "rd" suffix for a number.

239.  #ifdef OVL2
240.  const char *
241.  ordin(n)		/* return the ordinal suffix of a number */
242.      int n;			/* note: should be non-negative */
243.  {
244.      register int dd = n % 10;
245.  
246.      return (dd == 0 || dd > 3 || (n % 100) / 10 == 1) ? "th" :
247.  	    (dd == 1) ? "st" : (dd == 2) ? "nd" : "rd";
248.  }
249.  #endif /* OVL2 */
250.  

The string from ordin does not include the number, but it should be easy to use pline or snprintf to print the number:

pline("%d%s", i, ordin(i));

sitoa

The sitoa function converts an integer to ASCII, including the sign. It uses sprintf with either "%d" or "+%d", including the + for any nonnegative number. (This should use snprintf and check for overflow, but older systems do not have snprintf and the INT_MIN of -2147483648 or INT_MAX of +2147483647 fit in 12 bytes.)

251.  #ifdef OVL1
252.  char *
253.  sitoa(n)		/* make a signed digit string from a number */
254.      int n;
255.  {
256.      Static char buf[13];
257.  
258.      Sprintf(buf, (n < 0) ? "%d" : "+%d", n);
259.      return buf;
260.  }
261.  

The name of sitoa is short for signed integer to ascii. It is named for "itoa", the inverse of atoi. (There is no "itoa" function in NetHack or the C library.)

sgn

The sgn function extracts the sign from an integer, returning either -1 or 0 or 1. Though this is a common function (and there is a Wikipedia entry for sign function), it is not in the C library.

262.  int
263.  sgn(n)			/* return the sign of a number: -1, 0, or 1 */
264.      int n;
265.  {
266.      return (n < 0) ? -1 : (n != 0);
267.  }
268.  #endif /* OVL1 */
269.  

This could easily have been a macro function buried in global.h, like so many other simple functions from NetHack:

/* not in NetHack */
#define sgn(n) (((n) < 0) ? -1 : ((n) != 0))

rounddiv

270.  #ifdef OVLB
271.  int
272.  rounddiv(x, y)		/* calculate x/y, rounding as appropriate */
273.      long x;
274.      int  y;
275.  {
276.      int r, m;
277.      int divsgn = 1;
278.  
279.      if (y == 0)
280.  	panic("division by zero in rounddiv");
281.      else if (y < 0) {
282.  	divsgn = -divsgn;  y = -y;
283.      }
284.      if (x < 0) {
285.  	divsgn = -divsgn;  x = -x;
286.      }
287.      r = x / y;
288.      m = x % y;
289.      if (2*m >= y) r++;
290.  
291.      return divsgn * r;
292.  }
293.  #endif /* OVLB */
294.  

distmin

295.  #ifdef OVL0
296.  int
297.  distmin(x0, y0, x1, y1) /* distance between two points, in moves */
298.      int x0, y0, x1, y1;
299.  {
300.      register int dx = x0 - x1, dy = y0 - y1;
301.      if (dx < 0) dx = -dx;
302.      if (dy < 0) dy = -dy;
303.    /*  The minimum number of moves to get from (x0,y0) to (x1,y1) is the
304.     :  larger of the [absolute value of the] two deltas.
305.     */
306.      return (dx < dy) ? dy : dx;
307.  }
308.  

dist2

309.  int
310.  dist2(x0, y0, x1, y1)	/* square of euclidean distance between pair of pts */
311.      int x0, y0, x1, y1;
312.  {
313.      register int dx = x0 - x1, dy = y0 - y1;
314.      return dx * dx + dy * dy;
315.  }
316.  

online2

317.  boolean
318.  online2(x0, y0, x1, y1) /* are two points lined up (on a straight line)? */
319.      int x0, y0, x1, y1;
320.  {
321.      int dx = x0 - x1, dy = y0 - y1;
322.      /*  If either delta is zero then they're on an orthogonal line,
323.       *  else if the deltas are equal (signs ignored) they're on a diagonal.
324.       */
325.      return((boolean)(!dy || !dx || (dy == dx) || (dy + dx == 0)));	/* (dy == -dx) */
326.  }
327.  
328.  #endif /* OVL0 */

pmatch

329.  #ifdef OVLB
330.  
331.  boolean
332.  pmatch(patrn, strng)	/* match a string against a pattern */
333.      const char *patrn, *strng;
334.  {
335.      char s, p;
336.    /*
337.     :  Simple pattern matcher:  '*' matches 0 or more characters, '?' matches
338.     :  any single character.  Returns TRUE if 'strng' matches 'patrn'.
339.     */
340.  pmatch_top:
341.      s = *strng++;  p = *patrn++;	/* get next chars and pre-advance */
342.      if (!p)			/* end of pattern */
343.  	return((boolean)(s == '\0'));		/* matches iff end of string too */
344.      else if (p == '*')		/* wildcard reached */
345.  	return((boolean)((!*patrn || pmatch(patrn, strng-1)) ? TRUE :
346.  		s ? pmatch(patrn-1, strng) : FALSE));
347.      else if (p != s && (p != '?' || !s))  /* check single character */
348.  	return FALSE;		/* doesn't match */
349.      else				/* return pmatch(patrn, strng); */
350.  	goto pmatch_top;	/* optimize tail recursion */
351.  }
352.  #endif /* OVLB */
353.  

strncmpi

354.  #ifdef OVL2
355.  #ifndef STRNCMPI
356.  int
357.  strncmpi(s1, s2, n)	/* case insensitive counted string comparison */
358.      register const char *s1, *s2;
359.      register int n; /*(should probably be size_t, which is usually unsigned)*/
360.  {					/*{ aka strncasecmp }*/
361.      register char t1, t2;
362.  
363.      while (n--) {
364.  	if (!*s2) return (*s1 != 0);	/* s1 >= s2 */
365.  	else if (!*s1) return -1;	/* s1  < s2 */
366.  	t1 = lowc(*s1++);
367.  	t2 = lowc(*s2++);
368.  	if (t1 != t2) return (t1 > t2) ? 1 : -1;
369.      }
370.      return 0;				/* s1 == s2 */
371.  }
372.  #endif	/* STRNCMPI */
373.  #endif /* OVL2 */
374.  

strstri

375.  #ifdef OVLB
376.  #ifndef STRSTRI
377.  
378.  char *
379.  strstri(str, sub)	/* case insensitive substring search */
380.      const char *str;
381.      const char *sub;
382.  {
383.      register const char *s1, *s2;
384.      register int i, k;
385.  # define TABSIZ 0x20	/* 0x40 would be case-sensitive */
386.      char tstr[TABSIZ], tsub[TABSIZ];	/* nibble count tables */
387.  # if 0
388.      assert( (TABSIZ & ~(TABSIZ-1)) == TABSIZ ); /* must be exact power of 2 */
389.      assert( &lowc != 0 );			/* can't be unsafe macro */
390.  # endif
391.  
392.      /* special case: empty substring */
393.      if (!*sub)	return (char *) str;
394.  
395.      /* do some useful work while determining relative lengths */
396.      for (i = 0; i < TABSIZ; i++)  tstr[i] = tsub[i] = 0;	/* init */
397.      for (k = 0, s1 = str; *s1; k++)  tstr[*s1++ & (TABSIZ-1)]++;
398.      for (	s2 = sub; *s2; --k)  tsub[*s2++ & (TABSIZ-1)]++;
399.  
400.      /* evaluate the info we've collected */
401.      if (k < 0)	return (char *) 0;  /* sub longer than str, so can't match */
402.      for (i = 0; i < TABSIZ; i++)	/* does sub have more 'x's than str? */
403.  	if (tsub[i] > tstr[i])	return (char *) 0;  /* match not possible */
404.  
405.      /* now actually compare the substring repeatedly to parts of the string */
406.      for (i = 0; i <= k; i++) {
407.  	s1 = &str[i];
408.  	s2 = sub;
409.  	while (lowc(*s1++) == lowc(*s2++))
410.  	    if (!*s2)  return (char *) &str[i];		/* full match */
411.      }
412.      return (char *) 0;	/* not found */
413.  }
414.  #endif	/* STRSTRI */
415.  

fuzzymatch

416.  /* compare two strings for equality, ignoring the presence of specified
417.     characters (typically whitespace) and possibly ignoring case */
418.  boolean
419.  fuzzymatch(s1, s2, ignore_chars, caseblind)
420.      const char *s1, *s2;
421.      const char *ignore_chars;
422.      boolean caseblind;
423.  {
424.      register char c1, c2;
425.  
426.      do {
427.  	while ((c1 = *s1++) != '\0' && index(ignore_chars, c1) != 0) continue;
428.  	while ((c2 = *s2++) != '\0' && index(ignore_chars, c2) != 0) continue;
429.  	if (!c1 || !c2) break;	/* stop when end of either string is reached */
430.  
431.  	if (caseblind) {
432.  	    c1 = lowc(c1);
433.  	    c2 = lowc(c2);
434.  	}
435.      } while (c1 == c2);
436.  
437.      /* match occurs only when the end of both strings has been reached */
438.      return (boolean)(!c1 && !c2);
439.  }
440.  
441.  #endif /* OVLB */

Time routines

442.  #ifdef OVL2
443.  
444.  /*
445.   * Time routines
446.   *
447.   * The time is used for:
448.   *	- seed for rand()
449.   *	- year on tombstone and yyyymmdd in record file
450.   *	- phase of the moon (various monsters react to NEW_MOON or FULL_MOON)
451.   *	- night and midnight (the undead are dangerous at midnight)
452.   *	- determination of what files are "very old"
453.   */
454.  
455.  #if defined(AMIGA) && !defined(AZTEC_C) && !defined(__SASC_60) && !defined(_DCC) && !defined(__GNUC__)
456.  extern struct tm *FDECL(localtime,(time_t *));
457.  #endif
458.  static struct tm *NDECL(getlt);
459.  

setrandom

460.  void
461.  setrandom()
462.  {
463.  	/* the types are different enough here that sweeping the different
464.  	 * routine names into one via #defines is even more confusing
465.  	 */
466.  #ifdef RANDOM	/* srandom() from sys/share/random.c */
467.  	srandom((unsigned int) time((time_t *)0));
468.  #else
469.  # if defined(__APPLE__) || defined(BSD) || defined(LINUX) || defined(ULTRIX) || defined(CYGWIN32) /* system srandom() */
470.  #  if defined(BSD) && !defined(POSIX_TYPES)
471.  #   if defined(SUNOS4)
472.  	(void)
473.  #   endif
474.  		srandom((int) time((long *)0));
475.  #  else
476.  		srandom((int) time((time_t *)0));
477.  #  endif
478.  # else
479.  #  ifdef UNIX	/* system srand48() */
480.  	srand48((long) time((time_t *)0));
481.  #  else		/* poor quality system routine */
482.  	srand((int) time((time_t *)0));
483.  #  endif
484.  # endif
485.  #endif
486.  }
487.  

getlt

488.  static struct tm *
489.  getlt()
490.  {
491.  	time_t date;
492.  
493.  #if defined(BSD) && !defined(POSIX_TYPES)
494.  	(void) time((long *)(&date));
495.  #else
496.  	(void) time(&date);
497.  #endif
498.  #if (defined(ULTRIX) && !(defined(ULTRIX_PROTO) || defined(NHSTDC))) || (defined(BSD) && !defined(POSIX_TYPES))
499.  	return(localtime((long *)(&date)));
500.  #else
501.  	return(localtime(&date));
502.  #endif
503.  }
504.  

getyear

505.  int
506.  getyear()
507.  {
508.  	return(1900 + getlt()->tm_year);
509.  }
510.  

yymmdd

511.  #if 0
512.  /* This routine is no longer used since in 2000 it will yield "100mmdd". */
513.  char *
514.  yymmdd(date)
515.  time_t date;
516.  {
517.  	Static char datestr[10];
518.  	struct tm *lt;
519.  
520.  	if (date == 0)
521.  		lt = getlt();
522.  	else
523.  #if (defined(ULTRIX) && !(defined(ULTRIX_PROTO) || defined(NHSTDC))) || defined(BSD)
524.  		lt = localtime((long *)(&date));
525.  #else
526.  		lt = localtime(&date);
527.  #endif
528.  
529.  	Sprintf(datestr, "%02d%02d%02d",
530.  		lt->tm_year, lt->tm_mon + 1, lt->tm_mday);
531.  	return(datestr);
532.  }
533.  #endif
534.  

yyyymmdd

535.  long
536.  yyyymmdd(date)
537.  time_t date;
538.  {
539.  	long datenum;
540.  	struct tm *lt;
541.  
542.  	if (date == 0)
543.  		lt = getlt();
544.  	else
545.  #if (defined(ULTRIX) && !(defined(ULTRIX_PROTO) || defined(NHSTDC))) || (defined(BSD) && !defined(POSIX_TYPES))
546.  		lt = localtime((long *)(&date));
547.  #else
548.  		lt = localtime(&date);
549.  #endif
550.  
551.  	/* just in case somebody's localtime supplies (year % 100)
552.  	   rather than the expected (year - 1900) */
553.  	if (lt->tm_year < 70)
554.  	    datenum = (long)lt->tm_year + 2000L;
555.  	else
556.  	    datenum = (long)lt->tm_year + 1900L;
557.  	/* yyyy --> yyyymm */
558.  	datenum = datenum * 100L + (long)(lt->tm_mon + 1);
559.  	/* yyyymm --> yyyymmdd */
560.  	datenum = datenum * 100L + (long)lt->tm_mday;
561.  	return datenum;
562.  }
563.  

phase_of_the_moon

564.  /*
565.   * moon period = 29.53058 days ~= 30, year = 365.2422 days
566.   * days moon phase advances on first day of year compared to preceding year
567.   *	= 365.2422 - 12*29.53058 ~= 11
568.   * years in Metonic cycle (time until same phases fall on the same days of
569.   *	the month) = 18.6 ~= 19
570.   * moon phase on first day of year (epact) ~= (11*(year%19) + 29) % 30
571.   *	(29 as initial condition)
572.   * current phase in days = first day phase + days elapsed in year
573.   * 6 moons ~= 177 days
574.   * 177 ~= 8 reported phases * 22
575.   * + 11/22 for rounding
576.   */
577.  int
578.  phase_of_the_moon()		/* 0-7, with 0: new, 4: full */
579.  {
580.  	register struct tm *lt = getlt();
581.  	register int epact, diy, goldn;
582.  
583.  	diy = lt->tm_yday;
584.  	goldn = (lt->tm_year % 19) + 1;
585.  	epact = (11 * goldn + 18) % 30;
586.  	if ((epact == 25 && goldn > 11) || epact == 24)
587.  		epact++;
588.  
589.  	return( (((((diy + epact) * 6) + 11) % 177) / 22) & 7 );
590.  }
591.  

friday_13th

592.  boolean
593.  friday_13th()
594.  {
595.  	register struct tm *lt = getlt();
596.  
597.  	return((boolean)(lt->tm_wday == 5 /* friday */ && lt->tm_mday == 13));
598.  }
599.  

night

600.  int
601.  night()
602.  {
603.  	register int hour = getlt()->tm_hour;
604.  
605.  	return(hour < 6 || hour > 21);
606.  }
607.  

midnight

608.  int
609.  midnight()
610.  {
611.  	return(getlt()->tm_hour == 0);
612.  }
613.  #endif /* OVL2 */
614.  
615.  /*hacklib.c*/