Judy1(3)						     Library Functions Manual							  Judy1(3)

NAME

       Judy1 macros - C library for creating and accessing a dynamic array of bits, using any value of a word as an index.

SYNOPSIS

       cc [flags] sourcefiles -lJudy

       #include <Judy.h>

       int     Rc_int;				// return code - integer
       Word_t  Rc_word; 			// return code - unsigned word
       Word_t  Index, Index1, Index2, Nth;

       Pvoid_t PJ1Array = (Pvoid_t) NULL;	// initialize Judy1 array

       J1S( Rc_int,  PJ1Array, Index);		// Judy1Set()
       J1U( Rc_int,  PJ1Array, Index);		// Judy1Unset()
       J1T( Rc_int,  PJ1Array, Index);		// Judy1Test()
       J1C( Rc_word, PJ1Array, Index1, Index2); // Judy1Count()
       J1BC(Rc_int,  PJ1Array, Nth, Index);	// Judy1ByCount()
       J1FA(Rc_word, PJ1Array); 		// Judy1FreeArray()
       J1MU(Rc_word, PJ1Array); 		// Judy1MemUsed()
       J1F( Rc_int,  PJ1Array, Index);		// Judy1First()
       J1N( Rc_int,  PJ1Array, Index);		// Judy1Next()
       J1L( Rc_int,  PJ1Array, Index);		// Judy1Last()
       J1P( Rc_int,  PJ1Array, Index);		// Judy1Prev()
       J1FE(Rc_int,  PJ1Array, Index);		// Judy1FirstEmpty()
       J1NE(Rc_int,  PJ1Array, Index);		// Judy1NextEmpty()
       J1LE(Rc_int,  PJ1Array, Index);		// Judy1LastEmpty()
       J1PE(Rc_int,  PJ1Array, Index);		// Judy1PrevEmpty()

DESCRIPTION

       A  Judy1  array is the equivalent of a bit array or bit map.  A bit is addressed by an Index (key).  The array may be sparse, and the Index
       may be any word-sized Value.  If an index is present, it represents a set bit (a bit set represents an index  present).	 If  an  index	is
       absent, it represents an unset bit (a bit unset represents an absent index).

       A Judy1 array is allocated with a NULL pointer

       Pvoid_t PJ1Array = (Pvoid_t) NULL;
       Memory  to  support  the  array is allocated as bits are set, and released as bits are unset.  If the Judy1 pointer (PJ1Array) is NULL, all
       bits are unset (and the Judy1 array requires no memory).

       As with an ordinary array, a Judy1 array contains no duplicate indexes.

       Using the macros described here, rather than the Judy1 function calls, the default error handling sends a message to the standard error and
       terminates the program with exit(1).  For other error handling methods, see the ERRORS section.

       Because	the  macro forms are sometimes faster and have a simpler error handling interface than the equivalent functions, they are the pre-
       ferred way of calling the Judy1 functions.

	J1S(Rc_int, PJ1Array, Index); // Judy1Set()
		      Set Index's bit in the Judy1 array PJ1Array.

		      Return Rc_int set to 1 if Index's bit was previously unset (successful), otherwise 0 if the bit was already set  (unsuccess-
		      ful).

	J1U(Rc_int, PJ1Array, Index); // Judy1Unset()
		      Unset Index's bit in the Judy1 array PJ1Array; that is, remove Index from the Judy1 array.

		      Return  Rc_int set to 1 if Index's bit was previously set (successful), otherwise 0 if the bit was already unset (unsuccess-
		      ful).

	J1T(Rc_int, PJ1Array, Index); // Judy1Test()
		      Test if Index's bit is set in the Judy1 array PJ1Array.

		      Return Rc_int set to 1 if Index's bit is set (Index is present), 0 if it is unset (Index is absent).

	J1C(Rc_word, PJ1Array, Index1, Index2); // Judy1Count()
		      Count the number of indexes present in the Judy1 array PJ1Array between Index1 and Index2 (inclusive).

		      Return Rc_word set to the count.	A return Value of 0 can be valid as a count, or it can indicate a special case	for  fully
		      populated array (32-bit machines only).  See Judy1Count() for ways to resolve this.

		      To count all indexes present (population) in a Judy1 bit array, use:

		      J1C(Rc_word, PJ1Array, 0, -1);
		      Note: The -1 promotes to the maximum index, that is, all ones.

	J1BC(Rc_int, PJ1Array, Nth, Index); // Judy1ByCount()
		      Locate the Nth index that is present in the Judy1 array PJ1Array (Nth = 1 returns the first index present).  To refer to the
		      last index in a fully populated array (all indexes present, which is rare), use Nth = 0.

		      Return Rc_int set to 1 and Index set to the Nth index if found, otherwise return Rc_int set to 0 (the Value  of  Index  con-
		      tains no useful information).

	J1FA(Rc_word, PJ1Array); // Judy1FreeArray()
		      Free the entire Judy1 array PJ1Array (much faster than using a J1N(), J1U() loop).

		      Return Rc_word set to the number of bytes freed, and PJ1Array set to NULL.

	J1MU(Rc_word, PJ1Array); // Judy1MemUsed()
		      Return  Rc_word  set to the number of bytes of memory currently in use by Judy1 array PJ1Array. This is a very fast routine,
		      and may be used after a J1S() or J1U() call with little performance impact.

	Judy1 Search Functions
		      The Judy1 search functions allow you to search for set or unset bits in the array.  You may  search  inclusively	or  exclu-
		      sively,  in  either  forward  or reverse directions.  All of the search functions use a similar calling sequence.  Rc_int is
		      returned set to 1 for a successful search and the found Index is returned.  Rc_int is returned set to 0 for an  unsuccessful
		      search, and Index contains no useful information.  The return code Rc_int must be checked prior to using the returned Index,
		      since a search failure is possible.

	J1F(Rc_int, PJ1Array, Index); // Judy1First()
		      Search (inclusive) for the first index present that is equal to or greater than the passed Index.  (Start with Index = 0	to
		      find  the first index in the array.)  J1F() is typically used to begin a sorted-order scan of the indexes present in a Judy1
		      array.

	J1N(Rc_int, PJ1Array, Index); // Judy1Next()
		      Search (exclusive) for the next index present that is greater than the passed Index.  J1N() is typically used to continue  a
		      sorted-order scan of the indexes present in a Judy1 array, or to locate a "neighbor" of a given index.

	J1L(Rc_int, PJ1Array, Index); // Judy1Last()
		      Search  (inclusive) for the last index present that is equal to or less than the passed Index.  (Start with Index = -1, that
		      is, all ones, to find the last index in the array.)  J1L() is typically used to begin a  reverse-sorted-order  scan  of  the
		      indexes present in a Judy1 array.

	J1P(Rc_int, PJ1Array, Index); // Judy1Prev()
		      Search (exclusive) for the previous index present that is less than the passed Index.  J1P() is typically used to continue a
		      reverse-sorted-order scan of the indexes present in a Judy1 array, or to locate a "neighbor" of a given index.

	J1FE(Rc_int, PJ1Array, Index); // Judy1FirstEmpty()
		      Search (inclusive) for the first absent index that is equal to or greater than the passed Index.	(Start with Index =  0	to
		      find the first index absent in the array.)

	J1NE(Rc_int, PJ1Array, Index); // Judy1NextEmpty()
		      Search (exclusive) for the next absent index that is greater than the passed Index.

	J1LE(Rc_int, PJ1Array, Index); // Judy1LastEmpty()
		      Search (inclusive) for the last absent index that is equal to or less than the passed Index.  (Start with Index = -1 to find
		      the last index absent in the array.)

	J1PE(Rc_int, PJ1Array, Index); // Judy1PrevEmpty()
		      Search (exclusive) for the previous absent index that is less than the passed Index.

ERRORS
: See: Judy_3.htm#ERRORS
EXAMPLE

       In the following example, errors in the J1S() or J1U() calls go to a user-defined procedure, process_malloc_failure.  This  is  not  needed
       when you use the default JUDYERROR() macro, since the default causes your program to exit on all failures, including malloc() failure.

       #include <stdio.h>
       #include <Judy.h>

       int main()			// Example program of Judy1 macro APIs
       {
	  Word_t Index; 		// index (or key)
	  Word_t Rcount;		// count of indexes (or bits set)
	  Word_t Rc_word;		// full word return value
	  int	 Rc_int;		// boolean values returned (0 or 1)

	  Pvoid_t PJ1Array = (Pvoid_t) NULL; // initialize Judy1 array

	  Index = 123456;
	  J1S(Rc_int, J1Array, Index);	// set bit at 123456
	  if (Rc_int == JERR) goto process_malloc_failure;
	  if (Rc_int == 1) printf("OK - bit successfully set at %lu
", Index);
	  if (Rc_int == 0) printf("BUG - bit already set at %lu
", Index);

	  Index = 654321;
	  J1T(Rc_int, J1Array, Index);	// test if bit set at 654321
	  if (Rc_int == 1) printf("BUG - set bit at %lu
", Index);
	  if (Rc_int == 0) printf("OK - bit not set at %lu
", Index);

	  J1C(Rcount, J1Array, 0, -1);	// count all bits set in array
	  printf("%lu bits set in Judy1 array
", Rcount);

	  Index = 0;
	  J1F(Rc_int, J1Array, Index);	// find first bit set in array
	  if (Rc_int == 1) printf("OK - first bit set is at %lu
", Index);
	  if (Rc_int == 0) printf("BUG - no bits set in array
");

	  J1MU(Rc_word, J1Array);	// how much memory was used?
	  printf("%lu Indexes used %lu bytes of memory
", Rcount, Rc_word);

	  Index = 123456;
	  J1U(Rc_int, J1Array, Index);	// unset bit at 123456
	  if (Rc_int == JERR) goto process_malloc_failure;
	  if (Rc_int == 1) printf("OK - bit successfully unset at %lu
", Index);
	  if (Rc_int == 0) printf("BUG - bit was not set at %lu
", Index);

	  return(0);
       }

AUTHOR

       Judy was invented by Doug Baskins and implemented by Hewlett-Packard.

SEE ALSO

       Judy(3), JudyL(3), JudySL(3), JudyHS(3),
       malloc(),
       the Judy website, http://judy.sourceforge.net, for more information and Application Notes.

																	  Judy1(3)