X-Git-Url: http://git.kpe.io/?a=blobdiff_plain;f=doc%2Fref.sgml;h=99234c410e200a23bb2ee9a97bd182e5436f3849;hb=7612015bdcfa851374a4e8c6f3ff68a8dd8b9a9a;hp=827ac079f6e3e39f5102540b8a8964bc3d1c2c59;hpb=b0b263f7735028b6198593365c8285a6367882af;p=uffi.git
diff --git a/doc/ref.sgml b/doc/ref.sgml
index 827ac07..99234c4 100644
--- a/doc/ref.sgml
+++ b/doc/ref.sgml
@@ -759,7 +759,7 @@ the array.
Examples
-(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))))
@@ -767,6 +767,14 @@ the array.
&t;
+
+ Notes
+
+ 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.
+
+
Side Effects
None.
@@ -1216,6 +1224,14 @@ much better with static allocation.
+
+ Notes
+
+ 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.
+
+
Side Effects
None.
@@ -1266,8 +1282,9 @@ a character.
Description
- Ensures that an object obtained by dereferencing a
-:char pointer is a character.
+ Ensures that an objects obtained by dereferencing
+:char and :unsigned-char
+pointers are a lisp character.
@@ -1488,6 +1505,92 @@ if a cstring returned by a function is &null;.
+
+
+ with-cast-pointer
+ Wraps a body of code with a pointer cast to a new type.
+
+ Macro
+
+
+ Syntax
+
+ with-cast-pointer (binding-name ptr type) & body body => value
+
+
+
+ Arguments and Values
+
+
+ ptr
+
+ A pointer to a foreign object.
+
+
+
+
+ type
+
+ A foreign type of the object being pointed to.
+
+
+
+
+ value
+
+ The value of the object where the pointer points.
+
+
+
+
+
+
+ Description
+
+ 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.
+
+
+
+ Examples
+
+(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)))))))
+
+
+
+ Side Effects
+ None.
+
+
+ Affected by
+ None.
+
+
+ Exceptional Situations
+ None.
+
+
+
@@ -1495,13 +1598,73 @@ if a cstring returned by a function is &null;.
Overview
- &uffi; has functions to two types of C-compatible
- strings, cstring and foreign 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.
-
+
+ &uffi; has functions to two types of
+C-compatible
+ strings: cstring and
+foreign strings.
+
+cstrings are used only 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.
+
+
+
+(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))))
+
+
+ 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.
+
+
+(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."))))
+
+
+ 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.
+
+
+(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)))
+
+
@@ -1602,7 +1765,7 @@ that returns a cstring.
Side Effects
- None.
+ On some implementations, this function allocates memory.
Affected by
@@ -1644,7 +1807,7 @@ that returns a cstring.
Description
Frees any memory possibly allocated by
- convert-to-cstring.
+ convert-to-cstring. On some implementions, a cstring is just the Lisp string itself.
@@ -1704,7 +1867,7 @@ that returns a cstring.
Description
- Binds a lexical variable to a newly allocated cstring. Automatically frees cstring.
+ Binds a symbol to a cstring created from conversion of a string. Automatically frees the cstring.
@@ -2014,7 +2177,7 @@ foreign function. If :void indicates module does not return
Syntax
- load-foreign-library filename &key module supporting-libraries => success
+ load-foreign-library filename &key module supporting-libraries force-load => success
@@ -2045,6 +2208,13 @@ link the foreign library. (Required by CMUCL)
+
+ force-load
+
+ Forces the loading of the library if it has been previously loaded.
+
+
+
success
@@ -2060,7 +2230,7 @@ otherwise &nil;.
Description
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 :force-load key.