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<TD width="40%" align="left">JudyHS(3)</TD>
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<TD width="40%" align="right">JudyHS(3)</TD>
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<P>
<!----------------->
<DT><B>NAME</B></DT>
<DD>
JudyHS macros - C library for creating and accessing a dynamic array,
using an array-of-bytes of <B>Length</B> as an <B>Index</B> and a word
as a <B>Value</B>.
<!----------------->
<P>
<DT><B>SYNOPSIS</B></DT>
<DD>
<B><PRE>
cc [flags] <I>sourcefiles</I> -lJudy
#include <Judy.h>
Word_t * PValue; // JudyHS array element
int Rc_int; // return flag
Word_t Rc_word; // full word return value
Pvoid_t PJHSArray = (Pvoid_t) NULL; // initialize JudyHS array
uint8_t * Index; // array-of-bytes pointer
Word_t Length; // number of bytes in Index
<A href="#JHSI" >JHSI</A>( PValue, PJHSArray, Index, Length); // <A href="JudyHS_funcs_3.htm#JudyHSIns">JudyHSIns()</A>
<A href="#JHSD" >JHSD</A>( Rc_int, PJHSArray, Index, Length); // <A href="JudyHS_funcs_3.htm#JudyHSDel">JudyHSDel()</A>
<A href="#JHSG" >JHSG</A>( PValue, PJHSArray, Index, Length); // <A href="JudyHS_funcs_3.htm#JudyHSGet">JudyHSGet()</A>
<A href="#JHSFA">JHSFA</A>(Rc_word, PJHSArray); // <A href="JudyHS_funcs_3.htm#JudyHSFreeArray">JudyHSFreeArray()</A>
</PRE></B>
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<DT><B>DESCRIPTION</B></DT>
<DD>
A JudyHS array is the equivalent of an array of word-sized
value/pointers. An <B>Index</B> is a pointer to an array-of-bytes of
specified length: <B>Length</B>. Rather than using a null terminated
string, this difference from <A href="JudySL_3.htm">JudySL(3)</A>
allows strings to contain all bits (specifically the null character).
This new addition (May 2004) to Judy arrays is a hybird using the best
capabilities of hashing and Judy methods. <B>JudyHS</B> does not have a
poor performance case where knowledge of the hash algorithm can be used
to degrade the performance.
<P>
Since JudyHS is based on a hash method, <B>Indexes</B> are not stored in
any particular order. Therefore the JudyHSFirst(), JudyHSNext(),
JudyHSPrev() and JudyHSLast() neighbor search functions are not
practical. The <B>Length</B> of each array-of-bytes can be from 0 to
the limits of <I>malloc()</I> (about 2GB).
<P>
The hallmark of <B>JudyHS</B> is speed with scalability, but memory
efficiency is excellent. The speed is very competitive with the best
hashing methods. The memory efficiency is similar to a linked list of
the same <B>Indexes</B> and <B>Values</B>. <B>JudyHS</B> is designed to
scale from 0 to billions of <B>Indexes</B>.
<P>
A JudyHS array is allocated with a <B>NULL</B> pointer
<PRE>
Pvoid_t PJHSArray = (Pvoid_t) NULL;
</PRE>
<P>
Because the macro forms of the API have a simpler error handling
interface than the equivalent
<A href="JudyHS_funcs_3.htm">functions</A>,
they are the preferred way to use JudyHS.
<P>
<DT>
<A name="JHSI"><B>JHSI(PValue, PJHSArray, Index, Length)</B></A> // <A href="JudyHS_funcs_3.htm#JudyHSIns">JudyHSIns()</A></DT>
<DD>
Given a pointer to a JudyHS array (<B>PJHSArray</B>), insert an
<B>Index</B> string of length: <B>Length</B> and a <B>Value</B> into the
JudyHS array: <B>PJHSArray</B>. If the <B>Index</B> is successfully
inserted, the <B>Value</B> is initialized to 0. If the <B>Index</B> was
already present, the <B>Value</B> is not modified.
<P>
Return <B>PValue</B> pointing to <B>Value</B>. Your program should use
this pointer to read or modify the <B>Value</B>, for example:
<PRE>
Value = *PValue;
*PValue = 1234;
</PRE>
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