+ <reference>
+ <title>Aggregate Types</title>
+ <partintro>
+ <title>Overview</title>
+ <para>
+ Aggregate types are comprised of one or more primitive types.
+ </para>
+ </partintro>
+
+ <refentry id="def-enum">
+ <refnamediv>
+ <refname>def-enum</refname>
+ <refpurpose>Defines a &c; enumeration.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>def-enum</function> <replaceable>name fields &key separator-string</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>A symbol that names the enumeration.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>fields</parameter></term>
+ <listitem>
+ <para>A list of field defintions. Each definition can be
+a symbol or a list of two elements. Symbols get assigned a value of the
+current counter which starts at <computeroutput>0</computeroutput> and
+increments by <computeroutput>1</computeroutput> for each subsequent symbol. It the field definition is a list, the first position is the symbol and the second
+position is the value to assign the the symbol. The current counter gets set
+to <computeroutput>1+</computeroutput> this value.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>separator-string</parameter></term>
+ <listitem>
+ <para>A string that governs the creation of constants. The
+default is <computeroutput>"#"</computeroutput>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Declares a &c; enumeration. It generates constants with integer values for the elements of the enumeration. The symbols for the these constant
+values are created by the <function>concatenation</function> of the
+enumeration name, separator-string, and field symbol. Also creates
+a foreign type with the name <parameter>name</parameter> of type
+<constant>:int</constant>.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-enum abc (:a :b :c))
+;; Creates constants abc#a (1), abc#b (2), abc#c (3) and defines
+;; the foreign type "abc" to be :int
+
+(def-enum efoo (:e1 (:e2 10) :e3) :separator-string "-")
+;; Creates constants efoo-e1 (1), efoo-e2 (10), efoo-e3 (11) and defines
+;; the foreign type efoo to be :int
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>Creates a :int foreign type, defines constants.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="def-struct">
+ <refnamediv>
+ <refname>def-struct</refname>
+ <refpurpose>Defines a &c; structure.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>def-struct</function> <replaceable>name &rest fields</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>A symbol that names the structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>fields</parameter></term>
+ <listitem>
+ <para>A variable number of field defintions. Each definition is a list consisting of a symbol naming the field followed by its foreign type.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Declares a structure. A special type is available as a slot
+in the field. It is a pointer that points to an instance of the parent
+structure. It's type is <constant>:pointer-self</constant>.
+
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-struct foo (a :unsigned-int)
+ (b (* :char))
+ (c (:array :int 10))
+ (next :pointer-self))
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>Creates a foreign type.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="get-slot-value">
+ <refnamediv>
+ <refname>get-slot-value</refname>
+ <refpurpose>Retrieves a value from a slot of a structure.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>get-slot-value</function> <replaceable>obj type field</replaceable> => <returnvalue>value</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>obj</parameter></term>
+ <listitem>
+ <para>A pointer to foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>A name of the foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>field</parameter></term>
+ <listitem>
+ <para>A name of the desired field in foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>value</returnvalue></term>
+ <listitem>
+ <para>The value of the field in the structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Accesses a slot value from a structure.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(get-slot-value foo-ptr 'foo-structure 'field-name)
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="get-slot-pointer">
+ <refnamediv>
+ <refname>get-slot-pointer</refname>
+ <refpurpose>Retrieves a pointer from a slot of a structure.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>get-slot-pointer</function> <replaceable>obj type field</replaceable> => <returnvalue>pointer</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>obj</parameter></term>
+ <listitem>
+ <para>A pointer to foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>A name of the foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>field</parameter></term>
+ <listitem>
+ <para>A name of the desired field in foreign structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>pointer</returnvalue></term>
+ <listitem>
+ <para>The value of the field in the structure.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ This is similar to <function>get-slot-value</function>. It
+ is used when the value of a slot is a pointer type.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(get-slot-pointer foo-ptr 'foo-structure 'my-char-ptr)
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="def-array-pointer">
+ <refnamediv>
+ <refname>def-array-pointer</refname>
+ <refpurpose>Defines a pointer to a array of type.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>def-array-pointer</function> <replaceable>name type</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>A name of the new foreign type.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>The foreign type of the array elements.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Defines a type tat is a pointer to an array of type.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-array-pointer byte-array-pointer :unsigned-char)
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>Defines a new foreign type.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="deref-array">
+ <refnamediv>
+ <refname>deref-array</refname>
+ <refpurpose>Deference an array.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>deref-array</function> <replaceable>array type positon</replaceable> => <returnvalue>value</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>array</parameter></term>
+ <listitem>
+ <para>A foreign array.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>The foreign type of the array.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>position</parameter></term>
+ <listitem>
+ <para>An integer specifying the position to retrieve from
+the array.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>value</returnvalue></term>
+ <listitem>
+ <para>The value stored in the position of the array.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Dereferences (retrieves) the value of an array element.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-array ca :char)
+(let ((fs (convert-to-foreign-string "ab")))
+ (values (null-char-p (deref-array fs 'ca 0))
+ (null-char-p (deref-array fs 'ca 2))))
+=> &nil;
+ &t;
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="def-union">
+ <refnamediv>
+ <refname>def-union</refname>
+ <refpurpose>Defines a foreign union type.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>def-union</function> <replaceable>name &rest fields</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>A name of the new union type.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>fields</parameter></term>
+ <listitem>
+ <para>A list of fields of the union.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Defines a foreign union type.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-union test-union
+ (a-char :char)
+ (an-int :int))
+
+(let ((u (allocate-foreign-object 'test-union))
+ (setf (get-slot-value u 'test-union 'an-int) (+ 65 (* 66 256)))
+ (prog1
+ (ensure-char-character (get-slot-value u 'test-union 'a-char))
+ (free-foreign-object u)))
+=> #\A
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>Defines a new foreign type.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+</reference>
+
+<reference>
+ <title>Objects</title>
+<partintro>
+<title>Overview</title>
+ <para>
+ Objects are entities that can allocated, referred to by pointers, and
+can be freed.
+ </para>
+</partintro>
+
+
+ <refentry id="allocate-foreign-object">
+ <refnamediv>
+ <refname>allocate-foreign-object</refname>
+ <refpurpose>Allocates an instance of a foreign object.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>allocate-foreign-object</function> <replaceable>type &optional size</replaceable> => <returnvalue>ptr</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>The type of foreign object to allocate. This parameter is evaluated.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>size</parameter></term>
+ <listitem>
+ <para>An optional size parameter that is evaluated. If specified, allocates and returns an
+array of <parameter>type</parameter> that is <parameter>size</parameter> members long. This parameter is evaluated.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>ptr</returnvalue></term>
+ <listitem>
+ <para>A pointer to the foreign object.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Allocates an instance of a foreign object. It returns a pointer to the object.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(def-struct ab (a :int) (b :double))
+(allocate-foreign-object 'ab)
+=> #<ptr>
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="free-foreign-object">
+ <refnamediv>
+ <refname>free-foreign-object</refname>
+ <refpurpose>Frees memory that was allocated for a foreign boject.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>free-foreign-object</function> <replaceable>ptr</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>ptr</parameter></term>
+ <listitem>
+ <para>A pointer to the allocated foreign object to free.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Frees the memory used by the allocation of a foreign object.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="with-foreign-object">
+ <refnamediv>
+ <refname>with-foreign-object</refname>
+ <refpurpose>Wraps the allocation of a foreign object around a body of code.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>with-foreign-object</function> <replaceable>(var type) &body body</replaceable> => <returnvalue>form-return</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>var</parameter></term>
+ <listitem>
+ <para>The variable name to bind.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>The type of foreign object to allocate. This parameter is evaluated.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>form-return</returnvalue></term>
+ <listitem>
+ <para>The result of evaluating the <parameter>body</parameter>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+This function wraps the allocation, binding, and destruction of a foreign object.
+On &cmucl; and
+&lw; platforms the object is stack allocated for efficiency. Benchmarks show that &acl; performs
+much better with static allocation.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <programlisting>
+(defun gethostname2 ()
+ "Returns the hostname"
+ (uffi:with-foreign-object (name '(:array :unsigned-char 256))
+ (if (zerop (c-gethostname (uffi:char-array-to-pointer name) 256))
+ (uffi:convert-from-foreign-string name)
+ (error "gethostname() failed."))))
+ </programlisting>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="size-of-foreign-type">
+ <refnamediv>
+ <refname>size-of-foreign-type</refname>
+ <refpurpose>Returns the number of data bytes used by a foreign object type.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>size-of-foreign-type</function> <replaceable>ftype</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>ftype</parameter></term>
+ <listitem>
+ <para>A foreign type specifier. This parameter is evaluated.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Returns the number of data bytes used by a foreign object type. This does not include any Lisp storage overhead.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <para>
+<programlisting>
+(size-of-foreign-object :unsigned-byte)
+=> 1
+(size-of-foreign-object 'my-100-byte-vector-type)
+=> 100
+</programlisting>
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1> <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="pointer-address">
+ <refnamediv>
+ <refname>pointer-address</refname>
+ <refpurpose>Returns the address of a pointer.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>pointer-address</function> <replaceable>ptr</replaceable> => <returnvalue>address</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>ptr</parameter></term>
+ <listitem>
+ <para>A pointer to a foreign object.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>address</parameter></term>
+ <listitem>
+ <para>An integer representing the pointer's address.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Returns the address as an integer of a pointer.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="deref-pointer">
+ <refnamediv>
+ <refname>deref-pointer</refname>
+ <refpurpose>Deferences a pointer.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>deref-pointer</function> <replaceable>ptr type</replaceable> => <returnvalue>value</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>ptr</parameter></term>
+ <listitem>
+ <para>A pointer to a foreign object.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>A foreign type of the object being pointed to.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>value</returnvalue></term>
+ <listitem>
+ <para>The value of the object where the pointer points.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Returns the object to which a pointer points.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <para>
+<programlisting>
+(let ((intp (allocate-foreign-object :int)))
+ (setf (deref-pointer intp :int) 10)
+ (prog1
+ (deref-pointer intp :int)
+ (free-foreign-object intp)))
+=> 10
+</programlisting>
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="ensure-char-character">
+ <refnamediv>
+ <refname>ensure-char-character</refname>
+ <refpurpose>Ensures that a dereferenced <constant>:char</constant> pointer is
+a character.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>ensure-char-character</function> <replaceable>object</replaceable> => <returnvalue>char</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>object</parameter></term>
+ <listitem>
+ <para>Either a character or a integer specifying a character code.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>char</returnvalue></term>
+ <listitem>
+ <para>A character.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Ensures that an object obtained by dereferencing a
+<constant>:char</constant> pointer is a character.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <para>
+<programlisting>
+(let ((fs (convert-to-foreign-string "a")))
+ (prog1
+ (ensure-char-character (deref-pointer fs :char))
+ (free-foreign-object fs)))
+=> #\a
+</programlisting>
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>Depending upon the implementation and what &uffi; expects, this
+macro may signal an error if the object is not a character or
+integer.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="ensure-char-integer">
+ <refnamediv>
+ <refname>ensure-char-integer</refname>
+ <refpurpose>Ensures that a dereferenced <constant>:char</constant> pointer is
+an integer.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>ensure-char-integer</function> <replaceable>object</replaceable> => <returnvalue>int</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>object</parameter></term>
+ <listitem>
+ <para>Either a character or a integer specifying a character code.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>int</returnvalue></term>
+ <listitem>
+ <para>An integer.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Ensures that an object obtained by dereferencing a
+<constant>:char</constant> pointer is an integer.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <para>
+<programlisting>
+(let ((fs (convert-to-foreign-string "a")))
+ (prog1
+ (ensure-char-integer (deref-pointer fs :char))
+ (free-foreign-object fs)))
+=> 96
+</programlisting>
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>Depending upon the implementation and what &uffi; expects, this
+macro may signal an error if the object is not a character or
+integer.</para>
+ </refsect1>
+ </refentry>
+
+ <refentry id="make-null-pointer">
+ <refnamediv>
+ <refname>make-null-pointer</refname>
+ <refpurpose>Create a &null; pointer.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>make-null-pointer</function> <replaceable>type</replaceable> => <returnvalue>ptr</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>A type of object to which the pointer refers.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>ptr</parameter></term>
+ <listitem>
+ <para>The &null; pointer of type <parameter>type</parameter>.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Creates a &null; pointer of a specified type.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="null-pointer-p">
+ <refnamediv>
+ <refname>null-pointer-p</refname>
+ <refpurpose>Tests a pointer for &null; value.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>null-pointer-p</function> <replaceable>ptr</replaceable> => <returnvalue>is-null</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>ptr</parameter></term>
+ <listitem>
+ <para>A foreign object pointer.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>is-null</returnvalue></term>
+ <listitem>
+ <para>The boolean flag.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ A predicate testing if a pointer is has a &null; value.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="null-cstring-pointer">
+ <refnamediv>
+ <refname>+null-cstring-pointer+</refname>
+ <refpurpose>A constant &null; cstring pointer.
+ </refpurpose>
+ <refclass>Constant</refclass>
+ </refnamediv>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ A &null; cstring pointer. This can be used for testing
+if a cstring returned by a function is &null;.
+ </para>
+ </refsect1>
+ </refentry>
+
+</reference>
+
+ <reference>
+ <title>Strings</title>
+<partintro>
+<title>Overview</title>
+<para>
+
+ &uffi; has functions to two types of
+<varname>C</varname>-compatible
+ strings: <emphasis>cstring</emphasis> and
+<emphasis>foreign</emphasis> strings.
+
+cstrings are used <emphasis>only</emphasis> as parameters to and from
+functions. In some implementations a cstring is not a foreign type but
+rather the Lisp string itself. On other platforms a cstring is a newly
+allocated foreign vector for storing characters. The following is an
+example of using cstrings to both send and return a value.
+</para>
+
+<programlisting>
+(uffi:def-function ("getenv" c-getenv)
+ ((name :cstring))
+ :returning :cstring)
+
+(defun my-getenv (key)
+ "Returns an environment variable, or NIL if it does not exist"
+ (check-type key string)
+ (uffi:with-cstring (key-native key)
+ (uffi:convert-from-cstring (c-getenv key-native))))
+</programlisting>
+
+<para> In contrast, foreign strings are always a foreign vector of
+characters which have memory allocated. Thus, if you need to allocate
+memory to hold the return value of a string, you must use a foreign
+string and not a cstring. The following is an example of using a foreign
+string for a return value. </para>
+
+<programlisting>
+(uffi:def-function ("gethostname" c-gethostname)
+ ((name (* :unsigned-char))
+ (len :int))
+ :returning :int)
+
+(defun gethostname ()
+ "Returns the hostname"
+ (let* ((name (uffi:allocate-foreign-string 256))
+ (result-code (c-gethostname name 256))
+ (hostname (when (zerop result-code)
+ (uffi:convert-from-foreign-string name))))
+ (uffi:free-foreign-object name)
+ (unless (zerop result-code)
+ (error "gethostname() failed."))))
+</programlisting>
+
+</partintro>
+
+ <refentry id="convert-from-cstring">
+ <refnamediv>
+ <refname>convert-from-cstring</refname>
+ <refpurpose>Converts a cstring to a Lisp string.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>convert-from-cstring</function> <replaceable>cstring</replaceable> => <returnvalue>string</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>cstring</parameter></term>
+ <listitem>
+ <para>A cstring.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>string</returnvalue></term>
+ <listitem>
+ <para>A Lisp string.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+ Converts a Lisp string to a <constant>cstring</constant>. This is
+most often used when processing the results of a foreign function
+that returns a cstring.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Side Effects</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Affected by</title>
+ <para>None.</para>
+ </refsect1>
+ <refsect1>
+ <title>Exceptional Situations</title>
+ <para>None.</para>
+ </refsect1>
+ </refentry>
+
+
+ <refentry id="convert-to-cstring">
+ <refnamediv>
+ <refname>convert-to-cstring</refname>
+ <refpurpose>Converts a Lisp string to a cstring.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>convert-to-cstring</function> <replaceable>string</replaceable> => <returnvalue>cstring</returnvalue>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>string</parameter></term>
+ <listitem>
+ <para>A Lisp string.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>cstring</returnvalue></term>
+ <listitem>
+ <para>A cstring.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>