pointer returns an character.</para>
</listitem>
<listitem>
- <para><constant>:byte</constant> - Unsigned 8-bits. A
+ <para><constant>:byte</constant> - Signed 8-bits. A
dereferenced :byte pointer returns an integer.</para>
+ </listitem>
+ <listitem>
+ <para><constant>:unsigned-byte</constant> - Unsigned 8-bits. A
+dereferenced :unsigned-byte pointer returns an integer.</para>
</listitem>
<listitem>
<para><constant>:short</constant> - Signed 16-bits.</para>
<refsect1>
<title>Examples</title>
<programlisting>
-(def-array ca :char)
+(def-array-pointer 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))))
&t;
</programlisting>
</refsect1>
+ <refsect1>
+ <title>Notes</title>
+ <para>
+ The TYPE argument is ignored for CL implementations other than
+ AllegroCL. If you want to cast a pointer to another type use
+ WITH-CAST-POINTER together with DEREF-POINTER/DEREF-ARRAY.
+ </para>
+ </refsect1>
<refsect1>
<title>Side Effects</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>
</programlisting>
</para>
</refsect1>
+ <refsect1>
+ <title>Notes</title>
+ <para>
+ The TYPE argument is ignored for CL implementations other than
+ AllegroCL. If you want to cast a pointer to another type use
+ WITH-CAST-POINTER together with DEREF-POINTER/DEREF-ARRAY.
+ </para>
+ </refsect1>
<refsect1>
<title>Side Effects</title>
<para>None.</para>
<refsect1>
<title>Description</title>
<para>
- Ensures that an object obtained by dereferencing a
-<constant>:char</constant> pointer is a character.
+ Ensures that an objects obtained by dereferencing
+<constant>:char</constant> and <constant>:unsigned-char</constant>
+pointers are a lisp character.
</para>
</refsect1>
<refsect1>
</refsect1>
</refentry>
+ <refentry id="with-cast-pointer">
+ <refnamediv>
+ <refname>with-cast-pointer</refname>
+ <refpurpose>Wraps a body of code with a pointer cast to a new type.
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>with-cast-pointer</function> (<replaceable>binding-name ptr type) & body body</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>
+ Executes BODY with POINTER cast to be a pointer to type TYPE. If
+ BINDING-NAME is provided the cast pointer will be bound to this
+ name during the execution of BODY. If BINDING-NAME is not provided
+ POINTER must be a name bound to the pointer which should be
+ cast. This name will be bound to the cast pointer during the
+ execution of BODY.
+
+ This is a no-op in AllegroCL but will wrap BODY in a LET form if
+ BINDING-NAME is provided.
+
+ This macro is meant to be used in conjunction with DEREF-POINTER or
+ DEREF-ARRAY. In Allegro CL the "cast" will actually take place in
+ DEREF-POINTER or DEREF-ARRAY.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+<programlisting>
+(with-foreign-object (size :int)
+ ;; FOO is a foreign function returning a :POINTER-VOID
+ (let ((memory (foo size)))
+ (when (mumble)
+ ;; at this point we know for some reason that MEMORY points
+ ;; to an array of unsigned bytes
+ (with-cast-pointer (memory :unsigned-byte)
+ (dotimes (i (deref-pointer size :int))
+ (do-something-with
+ (deref-array memory '(:array :unsigned-byte) i)))))))
+</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-foreign-var">
+ <refnamediv>
+ <refname>def-foreign-var</refname>
+ <refpurpose>
+Defines a symbol macro to access a variable in foreign code
+ </refpurpose>
+ <refclass>Macro</refclass>
+ </refnamediv>
+ <refsynopsisdiv>
+ <title>Syntax</title>
+ <synopsis>
+ <function>def-foreign-var</function> <replaceable>name type module</replaceable>
+ </synopsis>
+ </refsynopsisdiv>
+ <refsect1>
+ <title>Arguments and Values</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>
+A string or list specificying the symbol macro's name. If it is a
+ string, that names the foreign variable. A Lisp name is created
+ by translating #\_ to #\- and by converting to upper-case in
+ case-insensitive Lisp implementations. If it is a list, the first
+ item is a string specifying the foreign variable name and the
+ second it is a symbol stating the Lisp name.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>type</parameter></term>
+ <listitem>
+ <para>A foreign type of the foreign variable.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><returnvalue>module</returnvalue></term>
+ <listitem>
+ <para>
+ A string specifying the module (or library) the foreign variable
+ resides in. (Required by Lispworks)
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1>
+ <title>Description</title>
+ <para>
+Defines a symbol macro which can be used to access (get and set) the
+value of a variable in foreign code.
+ </para>
+ </refsect1>
+ <refsect1>
+ <title>Examples</title>
+ <refsect2>
+ <title>C code</title>
+<programlisting>
+ int baz = 3;
+
+ typedef struct {
+ int x;
+ double y;
+ } foo_struct;
+
+ foo_struct the_struct = { 42, 3.2 };
+
+ int foo () {
+ return baz;
+ }
+</programlisting>
+</refsect2>
+<refsect2>
+<title>Lisp code</title>
+<programlisting>
+ (uffi:def-struct foo-struct
+ (x :int)
+ (y :double))
+
+ (uffi:def-function ("foo" foo)
+ ()
+ :returning :int
+ :module "foo")
+
+ (uffi:def-foreign-var ("baz" *baz*) :int "foo")
+ (uffi:def-foreign-var ("the_struct" *the-struct*) foo-struct "foo")
+
+
+*baz*
+ => 3
+
+(incf *baz*)
+ => 4
+
+(foo)
+ => 4
+</programlisting>
+</refsect2>
+ </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>
+
</reference>
<reference>
<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 as parameters to and from functions. An implementation, such as CMUCL,
-may not convert these to a foreign type for efficiency sake. Thus, it is not
-possible to "allocate" a cstring. In contrast, foreign strings
-always need to have memory for them.
- </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>
+
+<para> Foreign functions that return pointers to freshly allocated
+strings should in general not return cstrings, but foreign strings.
+(There is no portable way to release such cstrings from Lisp.) The
+following is an example of handling such a function. </para>
+
+<programlisting>
+(uffi:def-function ("readline" c-readline)
+ ((prompt :cstring))
+ :returning (* :char))
+
+(defun readline (prompt)
+ "Reads a string from console with line-editing."
+ (with-cstring (c-prompt prompt)
+ (let* ((c-str (c-readline c-prompt))
+ (str (convert-from-foreign-string c-str)))
+ (uffi:free-foreign-object c-str)
+ str)))
+</programlisting>
+
</partintro>
<refentry id="convert-from-cstring">
</refsect1>
<refsect1>
<title>Side Effects</title>
- <para>None.</para>
+ <para>On some implementations, this function allocates memory.</para>
</refsect1>
<refsect1>
<title>Affected by</title>
<title>Description</title>
<para>
Frees any memory possibly allocated by
- <function>convert-to-cstring</function>.
+ <function>convert-to-cstring</function>. On some implementions, a cstring is just the Lisp string itself.
</para>
</refsect1>
<refsect1>
<refsect1>
<title>Description</title>
<para>
- Binds a lexical variable to a newly allocated <varname>cstring</varname>. Automatically frees <varname>cstring</varname>.
+ Binds a symbol to a cstring created from conversion of a string. Automatically frees the <varname>cstring</varname>.
</para>
</refsect1>
<refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>
- <function>load-foreign-library</function> <replaceable>filename &key module supporting-libraries</replaceable> => <returnvalue>success</returnvalue>
+ <function>load-foreign-library</function> <replaceable>filename &key module supporting-libraries force-load</replaceable> => <returnvalue>success</returnvalue>
</synopsis>
</refsect1>
<refsect1>
</para>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><parameter>force-load</parameter></term>
+ <listitem>
+ <para>Forces the loading of the library if it has been previously loaded.
+ </para>
+ </listitem>
+ </varlistentry>
<varlistentry>
<term><returnvalue>success</returnvalue></term>
<listitem>
<title>Description</title>
<para>Loads a foreign library. Applies a module name to functions
within the library. Ensures that a library is only loaded once during
-a session.
+a session. A library can be reloaded by using the <symbol>:force-load</symbol> key.
</para>
</refsect1>
<refsect1>
projects / uffi.git / blobdiff