::cffiTop, Main, Index

This is the reference for commands in the cffi namespace. See the Start page for an introductory usage guide. See Concepts for a mapping of C types and program elements to the script level.

The package is loaded in standard fashion with package require:

package require cffi

CommandsTop, Main, Index

alias [::cffi]Top, Main, Index

A command ensemble.

alias subcommand ...

Description

The ensemble supports the following subcommands:

body	Returns the resolved body of an alias.
clear	Deletes all aliases from the interpreter.
define	Defines one or more type aliases.
delete	Deletes aliases matching a pattern.
list	Returns a list of aliases that match the specified pattern.
load	Loads predefined type aliases.

Refer to the documentation of each subcommand for details.

alias body [::cffi]Top, Main, Index

Returns the resolved body of an alias.

alias body alias_name

Parameters

alias_name Name of alias to be retrieved.

Description

The alias must be one defined in the current scope.

Return value

Returns the resolved body of an alias.

alias clear [::cffi]Top, Main, Index

Deletes all aliases from the interpreter

alias clear

alias define [::cffi]Top, Main, Index

Defines one or more type aliases.

alias define name definition
alias define aliasdefs

Parameters

`aliasdefs`	Dictionary mapping alias names to their definition.
`definition`	Definition for the alias.
`name`	Name for type alias. Must begin with an alphabetic character and may contain alphanumerics and underscore.

Description

Given two arguments, creates an alias of the given name for passed definition. If a single argument is provided, it must be a dictionary mapping alias names to their definitions.

An error will be raised if an alias name matches a built-in type or if an alias of that name already exists with a different definition in the same scope.

The definition may itself be based on an existing alias. In this case the existing alias is immediately resolved and expanded as part of the definition so further changes to it are not reflected in the alias being defined.

See Type aliases for more on type aliases.

alias delete [::cffi]Top, Main, Index

Deletes aliases matching a pattern.

alias delete pattern

Parameters

pattern Pattern to match against aliases.

Description

The command deletes all aliases whose name matches the specified pattern. The conditions for matching the pattern are:

the tail of the pattern must match the tail of the alias name using Tcl's glob pattern matching rules.
the scope component of the alias name must match exactly.

alias list [::cffi]Top, Main, Index

Returns a list of aliases that match the specified pattern.

alias list ?pattern?

Parameters

pattern Pattern to match against aliases. Optional, default *.

Description

The command returns the alias names that match the specified pattern. The conditions for matching the pattern are:

the tail of the pattern must match the tail of the alias name using Tcl's glob pattern matching rules.
the scope component of the alias name must match the pattern's scope exactly. If the pattern does not include a scope, the caller's scope is assumed.

Return value

Returns a list of aliases that match the specified pattern.

alias load [::cffi]Top, Main, Index

Loads predefined type aliases.

alias load alias_set

Parameters

alias_set The alias set to load.

Description

The aliases are loaded into the ::cffi::c scope. Since this scope is also searched when looking up aliases, the aliases defined by this command is available in all namespace without explicit qualification.

The possible values of $alias_set are C, win32 (Windows only), or posix (platform dependent).

The C predefined alias set includes _Bool, bool, int8_t uint8_t int16_t uint16_t int32_t uint32_t int64_t uint64_t size_t ssize_t

The win32 predefined alias set includes BOOL BOOLEAN BYTE CHAR DWORD DWORDLONG DWORD_PTR HALF_PTR HANDLE INT INT_PTR LONG LONGLONG LONG_PTR LPARAM LPVOID LRESULT SHORT SIZE_T SSIZE_T UCHAR UINT UINT_PTR ULONG ULONGLONG ULONG_PTR USHORT WORD WPARAM

The posix alias set is platform dependent. In POSIX compliant environments, it includes blkcnt_t blksize_t clock_t dev_t fsblkcnt_t fsfilcnt_t gid_t id_t ino_t key_t mode_t nlink_t off_t pid_t size_t ssize_t suseconds_t time_t uid_t. On Windows, it only includes dev_t ino_t off_t time_t.

arena [::cffi]Top, Main, Index

A command ensemble.

arena subcommand ...

Description

The ensemble supports the following subcommands:

allocate	Allocates memory in the current arena frame in the memory arena.
new	Allocates memory in the current arena for a type and initializes it.
popframe	Pops the current frame from the memory arena.
pushframe	Pushes a new stack frame on the memory arena.

Refer to the documentation of each subcommand for details.

arena allocate [::cffi]Top, Main, Index

Allocates memory in the current arena frame in the memory arena.

arena allocate sizespec ?tag?

Parameters

`sizespec`	Requested size of memory block. This may be specified either as an integer value or a type specification (optional)
`tag`	Tag for returned pointer. Optional, default `""`.

Description

The allocated memory will stay allocated until the frame is destroyed with arena popframe. The size $sizespec may be specified as a positive integer or a CFFI type declaration in which case the memory allocated is that of the type's size.

Return value

Returns a safe pointer to the allocation.

arena new [::cffi]Top, Main, Index

Allocates memory in the current arena for a type and initializes it.

arena new typespec initializer ?tag?

Parameters

`typespec`	A type declaration.
`initializer`	The type-specific value to use to initialize allocated memory.
`tag`	The optional tag for the returned pointer. Optional, default `""`.

Description

The $typespec argument may be any type specificiation. If an array is specified of a larger size than the number of elements in $initializer, the remaining elements are zeroed out.

The returned memory will be freed when the arena frame is freed with arena popframe.

Return value

Returns a safe pointer to the allocated memory.

arena popframe [::cffi]Top, Main, Index

Pops the current frame from the memory arena.

arena popframe

Description

All allocations from the popped frame are freed and pointers to these unregistered.

arena pushframe [::cffi]Top, Main, Index

Pushes a new stack frame on the memory arena.

arena pushframe ?size?
arena pushframe size ?tag?

Parameters

`sizespec`	Requested size of memory block. This may be specified either as an integer value or a type specification (optional)
`tag`	Tag for returned pointer if `$size` is specified (optional)

Description

The command allocate a new frame in the memory arena stack. All allocations from this frame will stay valid only until the corresponding call to arena popframe.

If no arguments are specified, the command initializes an empty frame. Otherwise it allocates storage of $sizespec bytes within the new frame and returns a pointer to it. The size $sizespec may be specified as a positive integer or a CFFI type declaration in which case the memory allocated is that of the type's size.

Return value

Returns an empty string if not arguments were specified or a safe pointer.

call [::cffi]Top, Main, Index

Invokes a C function through a function pointer.

call fnptr ?args?

Parameters

`fnptr`	A pointer value tagged with a prototype
`args`	Additional arguments to pass to the C function.

Description

The passed pointer $fnptr tag must corresponding to a function prototype defined through the prototype function or prototype stdcall commands.

Return value

Returns the value returned by the invoked C function.

callback [::cffi]Top, Main, Index

A command ensemble.

callback subcommand ...

Description

The ensemble supports the following subcommands:

free	Frees a callback pointer.
new	Wraps a script level command into a C function.

Refer to the documentation of each subcommand for details.

callback free [::cffi]Top, Main, Index

Frees a callback pointer

callback free cb

Parameters

`cb`	A function pointer allocated with callback new

callback new [::cffi]Top, Main, Index

Wraps a script level command into a C function

callback new protoname cmdprefix error_value

Parameters

`protoname`	The name of a prototype created through the prototype function or prototype stdcall commands.
`cmdprefix`	The command prefix that should be invoked when the created C function is called.
`error_value`	The value that should be returned if the command prefix raises an exception. This is optional if the function prototype specifies the `void` return type.

Description

The returned function pointer can be invoked through the call command but the common usage is for it to be passed to a C function that takes a callback function as an argument.

Invoking the function pointer will result in $cmdprefix being called with the additional arguments passed in the invocation. These must match the parameter types of the prototype specified in the callback definition.

The type declarations in a prototypes used for callbacks have certain restrictions. These arise because the "data flow" is now from script to the C shared library.

The parameter and return type are restricted to be scalar values and strings.

The out, inout and retval annotations are not permitted. This means any values to be returned to the shared library must be through explicit raw pointers.
All pointer type declarations must have the unsafe annotation. Other pointer safety annotations counted, dispose, disposeonsuccess cannot be specified.
The value checking annotations zero, nonzero, positive and nonnegative cannot be specified for the prototype return type.
The error handling annotations errno, winerror, lasterror and onerror cannot be specified.
The storeonerror and storealways annotations cannot be specified.

When $cmdprefix is called from a C function as a callback, it is executed in the Tcl context from which the C function was called and thus has access to the script level local variables etc.

When no longer needed, the callback should be freed with the callback free command.

Return value

Returns a callback function pointer that can be called from C native code.

enum [::cffi]Top, Main, Index

A command ensemble.

enum subcommand ...

Description

The ensemble supports the following subcommands:

alias	Defines a new enumeration and alias of the same name.
clear	Deletes all enumerations from the interpreter.
define	Defines a new enumeration.
delete	Deletes enumerations.
flags	Defines an enumeration as bit flags.
list	Lists enumerations.
mask	Returns an integer mask formed by bitwise OR-ing the passed enumeration members.
members	Returns a dictionary containing the members in an enumeration.
name	Returns the symbolic name of a value in an enumeration.
names	Returns a list containing the names of members in an enumeration.
sequence	Defines an enumeration with consecutive member values.
unmask	Returns a list of enumeration member names corresponding to the bits set in `$mask`.
value	Returns the value of an enumeration member.

Refer to the documentation of each subcommand for details.

enum alias [::cffi]Top, Main, Index

Defines a new enumeration and alias of the same name

enum alias enumname enumdefs typedecl

Parameters

`enumname`	Name of the enumeration.
`enumdefs`	Dictionary of enumeration member names to their values.
`typedecl`	The type to be used for the alias. Should have an integer base type and may contain other attributes except enum.

Description

The created alias has the same qualified name as the enum and has the corresponding enum attribute.

Return value

Returns the fully qualified enumeration name.

enum clear [::cffi]Top, Main, Index

Deletes all enumerations from the interpreter

enum clear

enum define [::cffi]Top, Main, Index

Defines a new enumeration.

enum define enumname enumdefs

Parameters

`enumname`	Name of the enumeration.
`enumdefs`	Dictionary of enumeration member names to their values.

Description

Parameter declarations can reference the enumeration to indicate that the corresponding symbol names are acceptible as arguments and will be replaced by the corresponding value in the function call. Enumeration member values must be integers.

Return value

Returns the fully qualified enumeration name.

enum delete [::cffi]Top, Main, Index

Deletes enumerations.

enum delete pattern

Parameters

pattern Pattern to match.

Description

The command deletes all enumerations whose name matches the specified pattern. The conditions for matching the pattern are:

the tail of the pattern must match the tail of the enumeration name using Tcl's glob pattern matching rules.
the scope component of the enumeration name must match exactly.

enum flags [::cffi]Top, Main, Index

Defines an enumeration as bit flags.

enum flags enumname membernames

Parameters

`enumname`	Name of the enumeration.
`membernames`	List of names of the enumeration members.

Description

For example,

enum flags E {A B C}

would define an enumeration with A, B, C values being 1, 2 and 4.

Return value

Returns the fully qualified enumeration name.

enum list [::cffi]Top, Main, Index

Lists enumerations.

enum list pattern

Parameters

pattern Pattern to match.

Description

The command returns the names of all enumerations whose name matches the specified pattern. The conditions for matching the pattern are:

the tail of the pattern must match the tail of the enumeration name using Tcl's glob pattern matching rules.
the scope component of the enumeration name must match exactly.

enum mask [::cffi]Top, Main, Index

Returns an integer mask formed by bitwise OR-ing the passed enumeration members

enum mask enumname membernames

Parameters

`enumname`	Name of the enumeration in the current scope
`membernames`	List of member names and integer values.

Return value

Returns an integer mask formed by bitwise OR-ing the passed enumeration members

enum members [::cffi]Top, Main, Index

Returns a dictionary containing the members in an enumeration.

enum members enumname

Parameters

enumname Name of the enumeration whose elements are to be returned.

Return value

Returns a dictionary containing the members in an enumeration.

enum name [::cffi]Top, Main, Index

Returns the symbolic name of a value in an enumeration.

enum name enumname membervalue ?default?

Parameters

`enumname`	Name of the enumeration.
`membervalue`	Value of an enumeration member.
`default`	Value to be returned if the member value is not found.

Description

The command will raise an error if $membervalue is not present in the enumeration and no default is provided, or if $enumname is itself undefined.

Return value

Returns the symbolic name of a value in an enumeration.

enum names [::cffi]Top, Main, Index

Returns a list containing the names of members in an enumeration.

enum names enumname

Parameters

enumname Name of the enumeration whose element names are to be returned.

Return value

Returns a list containing the names of members in an enumeration.

enum sequence [::cffi]Top, Main, Index

Defines an enumeration with consecutive member values

enum sequence enumname membernames ?start?

Parameters

`enumname`	Name of the enumeration.
`membernames`	List of names of the enumeration members.
`start`	Value of first enumeration member. Optional, default `0`.

Description

Each element of $membernames should have one or two elements, the first being the name of the member and the second, if present, being its value.If the second element is not present, the member is assigned a value one greater than the previous value assigned. The first member is assigned value 0 if it has no explicit assigned value.

The $start parameter is present for backward compatibility and indicates the first value to be assigned to the sequence. For future compatibility, the two-element form for the first enum member should be used instead if a starting value other than the default zero is desired.

Return value

Returns the fully qualified enumeration name.

enum unmask [::cffi]Top, Main, Index

Returns a list of enumeration member names corresponding to the bits set in $mask.

enum unmask enumname mask

Parameters

`enumname`	Name of the enumeration.
`mask`	Integer bit mask value.

Description

The last element of the returned list is $mask itself. Generally, the enumeration should consist of values that do not have overlapping bits set (commonly a single bit is set in each member value). This is not enforced but results might not be as expected if this condition is not met.

Return value

Returns a list of enumeration member names corresponding to the bits set in $mask.

enum value [::cffi]Top, Main, Index

Returns the value of an enumeration member

enum value enumname membername ?default?

Parameters

`enumname`	Name of the enumeration.
`membername`	Name of the enumeration member to retrieve.
`default`	Default value to be returned if the membername is not found.

Description

The command will raise an error if $membername is not present in the enumeration and no default is provided, or if $enumname is itself undefined.

Return value

Returns the value of an enumeration member

help [::cffi]Top, Main, Index

A command ensemble.

help subcommand ...

Description

The ensemble supports the following subcommands:

alias	Returns a string describing an alias definition.
enum	Returns a string describing an enum definition.
function	Returns a string describing the syntax and parameter definitions for a CFFI wrapped function.
functions	Returns a list of CFFI-wrapped functions matching the pattern `PATTERN`.
struct	Returns a string describing field types in a Struct.
union	Returns a string describing field types in a Union.

Refer to the documentation of each subcommand for details.

help alias [::cffi]Top, Main, Index

Returns a string describing an alias definition.

help alias NAME

Parameters

NAME Name of a alias

Return value

Returns a string describing an alias definition.

help enum [::cffi]Top, Main, Index

Returns a string describing an enum definition.

help enum NAME

Parameters

NAME Name of a enum

Return value

Returns a string describing an enum definition.

help function [::cffi]Top, Main, Index

Returns a string describing the syntax and parameter definitions for a CFFI wrapped function.

help function NAME

Parameters

NAME Name of a wrapped function.

Return value

Returns a string describing the syntax and parameter definitions for a CFFI wrapped function.

help functions [::cffi]Top, Main, Index

Returns a list of CFFI-wrapped functions matching the pattern PATTERN.

help functions ?PATTERN?

Parameters

PATTERN Glob pattern to match. Optional, default *.

Description

Note that like Tcl's info commands the pattern is interpreted relative to the current namespace. So for example, to obtain the list of commands within a namespace, the namespace must also be included in the pattern. For example,

cffi::help functions ::libzip::*

Return value

Returns a list of CFFI-wrapped functions matching the pattern PATTERN.

help struct [::cffi]Top, Main, Index

Returns a string describing field types in a Struct.

help struct NAME

Parameters

NAME Name of a Struct

Return value

Returns a string describing field types in a Struct.

help union [::cffi]Top, Main, Index

Returns a string describing field types in a Union.

help union NAME

Parameters

NAME Name of a Union

Return value

Returns a string describing field types in a Union.

limits [::cffi]Top, Main, Index

Get the lower and upper limits for an integral base type

limits type

Parameters

type The base type.

Return value

Returns a pair containing the minimum and maximum values for the specified type.

memory [::cffi]Top, Main, Index

A command ensemble.

memory subcommand ...

Description

The ensemble supports the following subcommands:

allocate	Allocates memory of the specified size.
fill	Fills memory with a specified value.
free	Frees the memory referenced by the passed pointer.
frombinary	Allocates memory and copied the passed Tcl binary string into it.
fromstring	Allocates memory and stores a Tcl string in it in the specified encoding.
fromunistring	Allocates memory and stores a Tcl string as a sequence of Tcl_UniChars.
fromwinstring	Allocates memory and stores a Tcl string as a sequence of winchars.
get	Converts a native value in memory into a Tcl script level value.
get!	Converts a native value in memory into a Tcl script level value.
new	Allocates memory for a type and initializes it.
set	Converts a value as per a type specification and stores it in memory in native form.
set!	Converts a value as per a type specification and stores it in memory in native form.
tobinary	Returns the content of a memory block as a Tcl binary string.
tobinary!	Returns the content of a memory block as a Tcl binary string.
tostring	Returns the content of a memory block as a Tcl string.
tostring!	Returns the content of a memory block as a Tcl string.
tounistring	Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.
tounistring!	Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.
towinstring	Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.
towinstring!	Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.

Refer to the documentation of each subcommand for details.

memory allocate [::cffi]Top, Main, Index

Allocates memory of the specified size

memory allocate sizespec ?tag?

Parameters

`sizespec`	Requested size of memory block. This may be specified either as an integer value or a type specification.
`tag`	Tag for the returned pointer. Optional, default `""`.

Description

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory fill [::cffi]Top, Main, Index

Fills memory with a specified value

memory fill pointer bytevalue count ?offset?

Parameters

`pointer`	Safe pointer to memory.
`bytevalue`	A value in the range `0`-`255`
`count`	Number of bytes to be fill.
`offset`	Offset from `$pointer` of area to fill. May be negative for unsafe pointers. Optional, default `0`.

memory free [::cffi]Top, Main, Index

Frees the memory referenced by the passed pointer

memory free pointer

Parameters

pointer Safe pointer to memory to free.

Description

The memory must have been allocated using memory allocate, memory frombinary, memory fromstring or one of the methods of a Struct object. Null pointers are silently ignored.

memory frombinary [::cffi]Top, Main, Index

Allocates memory and copied the passed Tcl binary string into it.

memory frombinary bin_value ?tag?

Parameters

`bin_value`	A Tcl binary value.
`tag`	Tag for the returned pointer. Optional, default `""`.

Description

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory fromstring [::cffi]Top, Main, Index

Allocates memory and stores a Tcl string in it in the specified encoding.

memory fromstring value ?encoding?

Parameters

`value`	Tcl string value.
`encoding`	The encoding to use for conversion. If unspecified or the empty string, the system encoding is used. Optional, default `""`.

Description

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory fromunistring [::cffi]Top, Main, Index

Allocates memory and stores a Tcl string as a sequence of Tcl_UniChars.

memory fromunistring value

Parameters

value Tcl string value.

Description

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory fromwinstring [::cffi]Top, Main, Index

Allocates memory and stores a Tcl string as a sequence of winchars.

memory fromwinstring value

Parameters

value Tcl string value.

Description

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory get [::cffi]Top, Main, Index

Converts a native value in memory into a Tcl script level value

memory get pointer typespec ?index?

Parameters

`pointer`	Base address of memory location. The pointer must be a safe pointer but the tag is immaterial.
`typespec`	Type specification to use for conversion.
`index`	The index in memory from which value is to be retrieved. Care must be taken this is within bounds of the allocated space. Optional, default `0`.

Description

The command converts the data at a memory location into a Tcl script object as per the type specification $typespec. The memory address of the data is given by $pointer if $index is unspecified or 0. Otherwise $index is treated as an index into an array based at $pointer whose elements are of the type defined by $typespec and memory address used is that of the slot given by $index. For example, if $typespec is int and $index is 2, the memory address from which the value is read is at byte offset 8 assuming ints occupy 4 bytes. If $typespec is int[3], then the size of the type specification is 12, and an index of 2 will correspond to a byte offset of 24, not 8. Be aware of these semantics when reading arrays using non-0 indices.

memory get! [::cffi]Top, Main, Index

Converts a native value in memory into a Tcl script level value

memory get! pointer typespec ?index?

Parameters

`pointer`	Base address of memory location. The pointer is not checked for validity.
`typespec`	Type specification to use for conversion.
`index`	The index in memory from which value is to be retrieved. Care must be taken this is within bounds of the allocated space. Optional, default `0`.

Description

This command is identical to the memory get command except that it does not require $pointer to be a safe pointer. See the documentation of that command for details.

memory new [::cffi]Top, Main, Index

Allocates memory for a type and initializes it.

memory new typespec initializer ?tag?

Parameters

`typespec`	A type declaration.
`initializer`	The type-specific value to use to initialize allocated memory.
`tag`	The optional tag for the returned pointer. Optional, default `""`.

Description

The $typespec argument may be any type specificiation. If an array is specified of a larger size than the number of elements in $initializer, the remaining elements are zeroed out.

The returned memory must be eventually freed by calling memory free.

Return value

Returns a safe pointer to the allocated memory.

memory set [::cffi]Top, Main, Index

Converts a value as per a type specification and stores it in memory in native form

memory set pointer typespec value ?index?

Parameters

`pointer`	Base address of memory location. The pointer must be a safe pointer but the tag is immaterial.
`typespec`	Type specification.
`value`	The script level value to be stored.
`index`	The index in memory at which the value is to be stored. Care must be taken this is within bounds of the allocated space. Optional, default `0`.

Description

The command converts $value into the native form corresponding to the type specification $typespec. If $index is unspecified or 0, the native value is stored at the memory address given by $pointer. Otherwise $index is the treated as an index into an array whose elements are of the type defined by $typespec and the value is stored in the slot given by $index. For example, if $typespec is int and $index is 2, the memory address at which the value is written is at byte offset 8 assuming ints occupy 4 bytes. If $typespec is int[3], then the size of the type specification is 12, and an index of 2 will correspond to a byte offset of 24, not 8. Be aware of these semantics when writing arrays to non-0 indices to avoid memory corruption.

memory set! [::cffi]Top, Main, Index

Converts a value as per a type specification and stores it in memory in native form

memory set! pointer typespec value ?index?

Parameters

`pointer`	Base address of memory location. The pointer is not checked for validity.
`typespec`	Type specification.
`value`	The script level value to be stored.
`index`	The index in memory at which the value is to be stored. Care must be taken this is within bounds of the allocated space. Optional, default `0`.

Description

This command is identical to the memory set command except that it does not require $pointer to be a safe pointer. See the documentation of that command for details.

memory tobinary [::cffi]Top, Main, Index

Returns the content of a memory block as a Tcl binary string.

memory tobinary pointer size ?offset?

Parameters

`pointer`	Safe pointer to memory.
`size`	Number of bytes to copy from the memory block.
`offset`	Offset from `$pointer` of area to value. May be negative for unsafe pointers. Optional, default `0`.

Return value

Returns the content of a memory block as a Tcl binary string.

memory tobinary! [::cffi]Top, Main, Index

Returns the content of a memory block as a Tcl binary string.

memory tobinary! pointer size ?offset?

Parameters

`pointer`	Pointer to memory.
`size`	Number of bytes to copy from the memory block.
`offset`	Offset from `$pointer` of area to value. May be negative for unsafe pointers. Optional, default `0`.

Description

Unlike the memory tobinary method, this does not check the validity of $pointer and should be used with care.

Return value

Returns the content of a memory block as a Tcl binary string.

memory tostring [::cffi]Top, Main, Index

Returns the content of a memory block as a Tcl string.

memory tostring pointer ?encoding? ?offset?

Parameters

`pointer`	Safe pointer to memory.
`encoding`	The encoding to use for conversion. If unspecified or the empty string, the system encoding is used. Optional, default `""`.
`offset`	Offset from `$pointer` of area to value. May be negative for unsafe pointers. Optional, default `0`.

Return value

Returns the content of a memory block as a Tcl string.

memory tostring! [::cffi]Top, Main, Index

Returns the content of a memory block as a Tcl string.

memory tostring! pointer ?encoding? ?offset?

Parameters

`pointer`	Pointer to memory. Need not be a safe pointer.
`encoding`	The encoding to use for conversion. If unspecified or the empty string, the system encoding is used. Optional, default `""`.
`offset`	Offset from `$pointer` of area to value. May be negative. Optional, default `0`.

Description

Unlike the memory tostring method, this does not check the validity of $pointer and should be used with care.

Return value

Returns the content of a memory block as a Tcl string.

memory tounistring [::cffi]Top, Main, Index

Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.

memory tounistring pointer ?offset?

Parameters

`pointer`	Safe pointer to memory.
`offset`	Offset in Tcl_UniChar units from `$pointer` of area to value. May be negative for unsafe pointers. Optional, default `0`.

Return value

Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.

memory tounistring! [::cffi]Top, Main, Index

Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.

memory tounistring! pointer ?offset?

Parameters

`pointer`	Pointer to memory. Need not be a safe pointer.
`offset`	Offset in Tcl_UniChar units from `$pointer` of area to value. May be negative. Optional, default `0`.

Return value

Returns the content of a memory block containing a nul-terminated sequence of Tcl_UniChars as a Tcl string.

memory towinstring [::cffi]Top, Main, Index

Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.

memory towinstring pointer ?offset?

Parameters

`pointer`	Safe pointer to memory.
`offset`	Offset in WCHAR units from `$pointer` of area to value. May be negative for unsafe pointers. Optional, default `0`.

Return value

Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.

memory towinstring! [::cffi]Top, Main, Index

Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.

memory towinstring! pointer ?offset?

Parameters

`pointer`	Pointer to memory. Need not be a safe pointer.
`offset`	Offset in WCHAR units from `$pointer` of area to value. May be negative. Optional, default `0`.

Return value

Returns the content of a memory block containing a nul-terminated sequence of winchars as a Tcl string.

pkgconfig [::cffi]Top, Main, Index

A command ensemble.

pkgconfig subcommand ...

Description

The ensemble supports the following subcommands:

get	Gets the value of a configuration key.
list	Returns the list of keys containing information about the package configuration.

Refer to the documentation of each subcommand for details.

pkgconfig get [::cffi]Top, Main, Index

Gets the value of a configuration key.

pkgconfig get key

Parameters

key One of the keys returned by pkgconfig list command.

Description

The following keys are supported.

`backend`	Returns `libffi` or `dyncall` indicating the backend FFI library in use.
`version`	The package version.
`compiler`	Identifies the compiler used to build the extension.

pkgconfig list [::cffi]Top, Main, Index

Returns the list of keys containing information about the package configuration.

pkgconfig list

Return value

Returns the list of keys containing information about the package configuration.

pointer [::cffi]Top, Main, Index

A command ensemble.

pointer subcommand ...

Description

The ensemble supports the following subcommands:

address	Returns the address component of the pointer.
cast	Casts a pointer to a new tag.
castable	Specifies that pointers with tag `$subtag` are acceptable in declarations that require `$supertag`.
castables	Returns a list of tags that have been marked as castable with the pointer castable command..
check	Validates a pointer and raise an exception if invalid.
compare	Compares if two pointers are the same.
counted	Registers a pointer as a counted pointer.
dispose	Unregisters a safe or counted pointer.
info	Returns a dictionary containing registration information about a pointer.
invalidate	Unregisters a safe, counted or pinned pointer irrespective its reference count.
isnull	Returns true if the pointer is a NULL pointer, false otherwise.
isvalid	Validates a pointer.
list	Returns a list of registered pointers optionally filtered by a tag.
make	Return a pointer for a memory address.
pin	Pins a pointer as permanently safe.
safe	Registers a pointer as a safe uncounted pointer.
tag	Returns the pointer tag.
uncastable	Makes pointers with the specified tag uncastable to another type.

Refer to the documentation of each subcommand for details.

pointer address [::cffi]Top, Main, Index

Returns the address component of the pointer.

pointer address pointer

Parameters

pointer Pointer whose address component is to be returned.

Return value

Returns the address component of the pointer.

pointer cast [::cffi]Top, Main, Index

Casts a pointer to a new tag.

pointer cast pointer ?TAG?

Parameters

`pointer`	Pointer to be cast.
`tag`	New tag to apply. This will be qualified with the current scope if not fully qualified.

Description

The cast will fail if the TAG is not castable to or from the pointer's tag. See Casting pointers. In addition, the cast will fail if the pointer is registered as a safe pointer and the pointer's tag is not castable to the tag in the registration.

If TAG is not specified, any existing tag is removed from the pointer (effectively marking it as a void* pointer).

Return value

Returns a pointer with the same address and new tag

pointer castable [::cffi]Top, Main, Index

Specifies that pointers with tag $subtag are acceptable in declarations that require $supertag.

pointer castable subtags supertag

Parameters

`subtags`	List of tags which are acceptable wherever `$supertag` is expected. Will be qualified with current scope if necessary.
`supertag`	Tag which should accept `$subtag` tagged pointers. Will be qualified with current scope if necessary.

Description

See Casting pointers for more information.

pointer castables [::cffi]Top, Main, Index

Returns a list of tags that have been marked as castable with the pointer castable command..

pointer castables

Return value

Returns a list of tags that have been marked as castable with the pointer castable command..

pointer check [::cffi]Top, Main, Index

Validates a pointer and raise an exception if invalid.

pointer check pointer

Parameters

pointer Pointer to be validated.

Description

For a pointer to be treated as valid,

it must not be NULL
it must be registered
if it is tagged, the tag must be the same as that of the registration or implicitly castable to it.

If any of the above conditions is not met, an error exception is raised. Note that if $pointer is untagged, the tag of the registration is not checked.

See Pointers for more on pointer safety and registration.

pointer compare [::cffi]Top, Main, Index

Compares if two pointers are the same

pointer compare ptr1 ptr2

Parameters

`ptr1`	The first pointer to compare.
`ptr2`	The second pointer to compare.

Return value

Returns 1 if both address and tag components match, -1 if address matches but tags are different and 0 otherwise.

pointer counted [::cffi]Top, Main, Index

Registers a pointer as a counted pointer

pointer counted pointer

Parameters

pointer Pointer to be registered.

Description

In the case that the pointer is already registered, behavior depends on the existing registration:

If the pointer is already registered as a pinned pointer, the command has no effect.
If the pointer is already registered as a counted pointer, the command has no effect if the tag is the same as the registered tag or can be implicitly cast to it. Otherwise the registered tag is replaced.
If the pointer is registered as an uncounted pointer, the registration, including tag, is overwritten as a counted pointer with a reference count of 1.

In the case that the pointer is registered with a different tag, if the pointer tag cannot be implicitly cast to the registered tag, the registered tag is replaced by the pointer tag.

See Pointers for more on counted pointers and registration.

Return value

Returns the registered pointer.

pointer dispose [::cffi]Top, Main, Index

Unregisters a safe or counted pointer

pointer dispose pointer

Parameters

pointer Pointer to be unregistered.

Description

Note that the command only unregisters the pointer. It does not do anything in terms of releases any resources associated with the pointer.

An error is raised if the pointer is not registered unless it is a null pointer in which case it is ignored without error.

See Pointers for more on pointer safety and registration.

pointer info [::cffi]Top, Main, Index

Returns a dictionary containing registration information about a pointer.

pointer info pointer

Parameters

pointer Pointer for which registration information is required.

Description

The returned dictionary always contains the keys Tag containing the pointer tag and Registration containing one of the values none, safe, pinned or counted. If the Registration value is not unregistered, the dictionary contains the additional keys RegisteredTag, holding the tag of the pointer in the registry, and Match which may have one of the values exact, derived or mismatch.

Return value

Returns a dictionary containing registration information about a pointer.

pointer invalidate [::cffi]Top, Main, Index

Unregisters a safe, counted or pinned pointer irrespective its reference count.

pointer invalidate pointer

Parameters

pointer Pointer to be unregistered.

Description

Note that the command only unregisters the pointer. It does not do anything in terms of releases any resources associated with the pointer.

The command differs from pointer dispose in that

it unregisters a counted pointer even if its reference count was greater than 1.
it unregisters pinned pointers
it does not raise an error for null pointers

See Pointers for more on pointer safety and registration.

pointer isnull [::cffi]Top, Main, Index

Returns true if the pointer is a NULL pointer, false otherwise.

pointer isnull pointer

Parameters

pointer Pointer to be checked.

Return value

Returns true if the pointer is a NULL pointer, false otherwise.

pointer isvalid [::cffi]Top, Main, Index

Validates a pointer.

pointer isvalid pointer

Parameters

pointer Pointer to be validated.

Description

For a pointer to be treated as valid,

it must not be NULL
it must be registered
if it is tagged, the tag must be the same as that of the registration or implicitly castable to it.

Return a boolean true value if all the above conditions are met, otherwise false.

See Pointers for more on pointer safety and registration.

pointer list [::cffi]Top, Main, Index

Returns a list of registered pointers optionally filtered by a tag.

pointer list ?tag?

Parameters

tag If specified, only pointers matching the tag are returned. If tag is the empty string, only pointers without a tag are returned.

Return value

Returns a list of registered pointers optionally filtered by a tag.

pointer make [::cffi]Top, Main, Index

Return a pointer for a memory address.

pointer make address ?tag?

Parameters

`address`	Memory address as a positive integer.
`tag`	If not fully qualified, this will be qualified with the current namespace name. An empty tag is treated as if it was unspecified.

Description

The returned pointer is not registered as safe. The caller can use the pointer safe command to mark it as such if so desired.

pointer pin [::cffi]Top, Main, Index

Pins a pointer as permanently safe.

pointer pin pointer

Parameters

pointer Pointer to be pinned. This may or may not be already registered.

Description

Once a pointer is pinned, it is unaffected by any pointer safe, pointer counted or pointer dispose calls. It can however be invalidated by pointer invalidate.

A pinned pointer has no associated tag even if the passed pointer has one. It will thus match any pointer with the same address component irrespective of the tag. The primary use of pinned pointers is to deal with "pseudo handles" in the Windows API.

Return value

Returns $pointer itself.

pointer safe [::cffi]Top, Main, Index

Registers a pointer as a safe uncounted pointer.

pointer safe pointer

Parameters

pointer Pointer to be registered.

Description

In the case that the pointer is already registered, behavior depends on the existing registration:

If the pointer is already registered as a pinned pointer, the command has no effect.
If the pointer is already registered as a safe (uncounted) pointer the command has no effect if the tag is the same as the registered tag or can be implicitly cast to it. Otherwise the registered tag is replaced.
If the pointer is registered as a counted pointer, the registration, including tag, is overwritten.

See Pointers for more on pointer safety and registration.

Return value

Returns the registered pointer.

pointer tag [::cffi]Top, Main, Index

Returns the pointer tag

pointer tag pointer

Parameters

pointer Pointer whose tag is to be returned.

Description

An empty string is returned if the pointer is not tagged.

See Pointers for more on pointer tags.

Return value

Returns the pointer tag

pointer uncastable [::cffi]Top, Main, Index

Makes pointers with the specified tag uncastable to another type

pointer uncastable tag

Parameters

tag A pointer tag Pointers tagged with $tag will no longer be castable to other tags that were configured with the pointer castables command.

prototype [::cffi]Top, Main, Index

A command ensemble.

prototype subcommand ...

Description

The ensemble supports the following subcommands:

delete	Deletes prototypes matching a pattern.
function	Defines a function prototype for calling a function using the default C calling convention.
list	Returns a list of prototypes matching the specified pattern.
stdcall	Defines a function prototype for calling a function using the stdcall calling convention.

Refer to the documentation of each subcommand for details.

prototype delete [::cffi]Top, Main, Index

Deletes prototypes matching a pattern.

prototype delete pattern

Parameters

pattern Pattern to match.

Description

The pattern matching algorithm is the same as that of Tcl's string match command. It is not an error if the pattern does not match any prototypes.

prototype function [::cffi]Top, Main, Index

Defines a function prototype for calling a function using the default C calling convention.

prototype function name fntype parameters

Parameters

`name`	Name for the prototype. Must begin with an alphabetic character and may contain alphanumerics and underscore.
`fntype`	The type definition for the return value from the function.
`parameters`	List of alternating parameter name and type definitions.

Description

The $fntype and $parameters take the same form and have the same semantics as described for the Wrapper.function method for defining functions. However, unlike that method, this command does not create a command for invoking a C function. It only defines a prototype that can then be used in conjunction with a C function address to invoke that function.

See Prototypes and function pointers for more details.

prototype list [::cffi]Top, Main, Index

Returns a list of prototypes matching the specified pattern.

prototype list ?pattern?

Parameters

pattern Pattern to match. Optional, default *.

Description

The pattern matching algorithm is the same as that of Tcl's string match command.

Return value

Returns a list of prototypes matching the specified pattern.

prototype stdcall [::cffi]Top, Main, Index

Defines a function prototype for calling a function using the stdcall calling convention.

prototype stdcall name fntype parameters

Parameters

`name`	Name for the prototype. Must begin with an alphabetic character and may contain alphanumerics and underscore.
`fntype`	The type definition for the return value from the function.
`parameters`	List of alternating parameter name and type definitions.

Description

The $fntype and $parameters take the same form and have the same semantics as described for the Wrapper.stdcall method for defining functions. However, unlike that method, this command does not create a command for invoking a C function. It only defines a prototype that can then be used in conjunction with a C function address to invoke that function.

See Prototypes and function pointers for more details.

savederrors [::cffi]Top, Main, Index

Return errno and GetLastError() values from the last CFFI call annotated with saveerrors.

savederrors

Description

For functions annotated with saveerrors, CFFI internally saves the errno and (on Windows) GetLastError() values. The savederrors command retrieves these as a pair with the first element being the saved errno value and the second the GetLastError() result. The latter is always 0 on non-Windows platforms.

type [::cffi]Top, Main, Index

A command ensemble.

type subcommand ...

Description

The ensemble supports the following subcommands:

count	Returns the count of elements in an array type.
frombinary	Converts the native binary value to its script level representation.
info	Returns a dictionary containing various information about a type declaration.
size	Returns the size of a type in terms of the number of bytes of memory occupied by that type.
tobinary	Converts a script level value to a native representation.

Refer to the documentation of each subcommand for details.

type count [::cffi]Top, Main, Index

Returns the count of elements in an array type

type count type

Parameters

type A type definition or alias.

Description

A return value of -1 indicates the type is not an array.

Return value

Returns the count of elements in an array type

type frombinary [::cffi]Top, Main, Index

Converts the native binary value to its script level representation.

type frombinary typespec value

Parameters

`typespec`	A type declaration.
`value`	The native binary value.

Description

The $typespec argument may be any type specification.

Return value

Returns the script level representation of the value.

type info [::cffi]Top, Main, Index

Returns a dictionary containing various information about a type declaration

type info typedecl ?args?

Parameters

`typedecl`	A type declaration.
`-parsemode MODE`	One of `param`, `return`, `field`.
`-vlacount VLACOUNT`	Number of elements in variable size array.

Description

The type is parsed as a parameter type declaration, a function return type declaration or a structure field type declaration depending on the -parsemode option. If this is unspecified or an empty string, it is parsed in generic fashion and no context-specific validation is done.

The option -vlacount must be specified if the type is variable length array or a struct that contains a variable length array

The returned dictionary contains the following keys:

Alignment	The memory alignment needed for a value of that type.
BaseSize	The number of bytes to store a single value of the type when the type is an array. For scalars, same as `Size`.
Count	`-1` for scalar values, else indicates the type is an array with that number of elements.
Size	The number of bytes of memory needed to store a value of that type.
Definition	The type declaration after applying any defaults. For type aliases, this is the resolved type definition.

Return value

Returns a dictionary containing various information about a type declaration

type size [::cffi]Top, Main, Index

Returns the size of a type in terms of the number of bytes of memory occupied by that type.

type size type ?args?

Parameters

`type`	A type definition or alias.
`-vlacount VLACOUNT`	Number of elements in variable size array.

Description

In the case of array types, the size includes the size of the entire array and not the size of a single element.

The option -vlacount must be specified if the type is variable length array or a struct that contains a variable length array

Return value

Returns the size of a type in terms of the number of bytes of memory occupied by that type.

type tobinary [::cffi]Top, Main, Index

Converts a script level value to a native representation.

type tobinary typespec value

Parameters

`typespec`	A type declaration.
`value`	The script level value.

Description

The $typespec argument must not have a string or variable size component. If an array is specified of a larger size than the number of elements in $value, the remaining elements are zeroed out.

Return value

Returns a Tcl binary containing the native representation.

ClassesTop, Main, Index

Interface [::cffi]Top, Main, Index

Method summary

constructor	Constructor for the class.
id	Returns the id for the interface as passed via the `-id` option in the interface definition.
methods	Creates Tcl commands wrapping the C functions comprising an interface.
stdmethods	Creates Tcl commands corresponding to the C functions comprising an interface.

constructor [::cffi::Interface]Interface, Top, Main, Index

Defines an interface consisting of method definitions.

Interface create OBJNAME ?args?
Interface new ?args?

Parameters

`-id ID`	An id to be associated with the interface. This is for the caller's use and CFFI does not make any use of it. For COM, this can be used to associate the GUID or IID for the interface. Defaults to the empty string.
`-inherit BASEINTERFACE`	If specified, the interface inherits methods from `BASEINTERFACE`. An empty value for `BASEINTERFACE` is treated as though the option was not specified.

Description

See Interfaces for more information.

id [::cffi::Interface]Interface, Top, Main, Index

Returns the id for the interface as passed via the -id option in the interface definition.

OBJECT id

Return value

Returns the id for the interface as passed via the -id option in the interface definition.

methods [::cffi::Interface]Interface, Top, Main, Index

Creates Tcl commands wrapping the C functions comprising an interface.

OBJECT methods methodlist ?args?

Parameters

`methodlist`	List of function definitions.
`-disposemethod METHODNAMDE`	The name of the method, if any, whose implicit pointer parameter should be annotated with `dispose`.

Description

The C functions in the wrapper are presumed to be using the _cdecl calling convention. The created commands are of the form INTERFACENAME.METHODNAME. The first argument to each is typed as pointer.INTERFACENAME.

The order of the methods in $methodlist must be the same as that in the corresponding C interface. All functions in the interface are expected to have a pointer to the interface as the first parameter.

The $methodlist argument is a flat (not nested) list of function name, return type and parameter list in the same form as described for the ::cffi::Wrapper::function method except that the first parameter in the C function, the pointer to the object, should not be included.

stdmethods [::cffi::Interface]Interface, Top, Main, Index

Creates Tcl commands corresponding to the C functions comprising an interface.

OBJECT stdmethods methodlist ?args?

Parameters

`methodlist`	List of function definitions.
`-disposemethod METHODNAMDE`	The name of the method, if any, whose implicit pointer parameter should be annotated with `dispose`.

Description

The C functions are presumed to be using the _stdcall calling convention. The created commands are of the form INTERFACENAME.METHODNAME. The first argument to each is typed as pointer.INTERFACENAME.

Struct [::cffi]Top, Main, Index

Method summary

constructor	Constructor for the class.
allocate	Allocates memory for one or more C structs.
describe	Returns a human-readable description of the C struct definition.
fieldpointer	Returns a pointer corresponding to the address of a field within a native structure.
free	Frees memory that was allocated for a native C struct.
frombinary	Decodes a Tcl binary string containing a native C struct into a Tcl dictionary.
fromnative	Decodes native C struct(s) in memory into a Tcl dictionary.
fromnative!	Decodes native C struct(s) in memory into a Tcl dictionary.
getnative	Returns the value of a field in a native structure in memory.
getnative!	Returns the value of a field in a native structure in memory.
getnativefields	Retrieve values of multiple fields from a native struct in memory.
getnativefields!	Retrieve values of multiple fields from a native struct in memory.
info	Returns a dictionary containing information about the struct layout.
name	Returns the name of the struct.
new	Allocates and initializes a native struct in memory.
setnative	Sets the value of a field in a native structure in memory.
setnative!	Sets the value of a field in a native structure in memory.
size	Returns the size of the struct.
tobinary	Encodes the Tcl representation of a C struct value into a Tcl binary string.
tonative	Writes the Tcl dictionary representation of a C struct value to memory in native form.
tonative!	Writes the Tcl dictionary representation of a C struct value to memory in native form.

constructor [::cffi::Struct]Struct, Top, Main, Index

Constructs a script level object that maps to a C struct definition.

Struct create OBJNAME definition ?args?
Struct new definition ?args?

Parameters

`definition`	Defines the layout and type of the C struct fields.
`-clear`	Clears memory at initialization. See below.
`-pack PACKVALUE`	Changes alignment and padding used for fields. See Structs.

Description

The created object can be used to pass arguments to and from functions, allocate memory, encode and decode native C structs in memory etc.

The $definition argument is a dictionary mapping field names to the corresponding types. See Packed structs for more information.

The name of the created struct is the same as the name of the returned object without the initial :: global namespace qualifier. This name can be retrieved with the name method and is used to identify the struct when tagging pointers and for typing function parameters and nested struct fields.

If the -clear option is present, the memory of structures of this type is cleared before the field values are initialized. In this case, missing field values in a struct value will not result in an error being raised even if no default annotation is included for the field. This also effectively provides a default zero value for all fields.

allocate [::cffi::Struct]Struct, Top, Main, Index

Allocates memory for one or more C structs.

OBJECT allocate ?args?

Parameters

`-count COUNT`	Number of structs to allocate.
`-vlacount VLACOUNT`	Number of elements in variable size array.

Description

Unlike in the new method, the allocated memory is not initialized. This is the case even if the struct definition includes the -clear option.

The option -vlacount must be specified if the struct contains a field that is a variable length array (VLA) or a nested struct that contains a VLA. VLACOUNT is then length of that array.

The allocate memory must be freed by calling the free method of the struct.

Return value

Returns a safe pointer to the allocated memory tagged with the struct name.

describe [::cffi::Struct]Struct, Top, Main, Index

Returns a human-readable description of the C struct definition.

OBJECT describe

Description

This is primarily for debugging and troubleshooting purposes. Note the returned information will not take into account the variable components of the struct if any.

Return value

Returns a human-readable description of the C struct definition.

fieldpointer [::cffi::Struct]Struct, Top, Main, Index

Returns a pointer corresponding to the address of a field within a native structure

OBJECT fieldpointer pointer fieldname ?tag? ?index?

Parameters

`pointer`	Pointer to memory allocated for the C struct or array. Must be a safe pointer tagged with the struct name.
`fieldname`	Name of the field.
`tag`	Tag for the returned pointer. Optional, default `""`.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

Note the returned pointer is not registered as a safe pointer.

Return value

Returns a pointer corresponding to the address of a field within a native structure

free [::cffi::Struct]Struct, Top, Main, Index

Frees memory that was allocated for a native C struct.

OBJECT free pointer

Parameters

pointer A pointer returned by allocate

frombinary [::cffi::Struct]Struct, Top, Main, Index

Decodes a Tcl binary string containing a native C struct into a Tcl dictionary.

OBJECT frombinary bin_value

Parameters

bin_value A Tcl binary value containing the C struct.

Return value

Returns the dictionary representation.

fromnative [::cffi::Struct]Struct, Top, Main, Index

Decodes native C struct(s) in memory into a Tcl dictionary.

OBJECT fromnative pointer ?index?

Parameters

`pointer`	Safe pointer to the C struct or array of structs in memory.
`index`	The index position at which the struct is to be written. Note this interpreted as an index into an array of structs, not as a byte offset into memory. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

The decoded dictionary or dictionaries are keyed by the field names of the struct. For fields containing variable length arrays, the field holding the length of the array must be explicitly specified and cannot be defaulted.

Return value

Returns a dictionary of the decoded struct.

fromnative! [::cffi::Struct]Struct, Top, Main, Index

Decodes native C struct(s) in memory into a Tcl dictionary.

OBJECT fromnative! pointer ?index?

Parameters

`pointer`	Safe or unsafe pointer to the C struct or array of structs in memory.
`index`	The index position at which the struct is to be written. Note this interpreted as an index into an array of structs, not as a byte offset into memory. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

Return value

Returns a dictionary of the decoded struct.

getnative [::cffi::Struct]Struct, Top, Main, Index

Returns the value of a field in a native structure in memory

OBJECT getnative pointer fieldname ?index?

Parameters

`pointer`	Safe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`fieldname`	Name of the field.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

In the case of fields of type pointer, the returned pointer is registered as a safe pointer unless the field was marked with the unsafe annotation.

Return value

Returns the value of a field in a native structure in memory

getnative! [::cffi::Struct]Struct, Top, Main, Index

Returns the value of a field in a native structure in memory

OBJECT getnative! pointer fieldname ?index?

Parameters

`pointer`	Safe or unsafe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`fieldname`	Name of the field.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

In the case of fields of type pointer, the returned pointer is registered as a safe pointer unless the field was marked with the unsafe annotation.

Return value

Returns the value of a field in a native structure in memory

getnativefields [::cffi::Struct]Struct, Top, Main, Index

Retrieve values of multiple fields from a native struct in memory.

OBJECT getnativefields pointer fieldnames ?index?

Parameters

`pointer`	Pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`fieldnames`	List of field names.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Return value

Returns a list of field values in the same order as $fieldnames

getnativefields! [::cffi::Struct]Struct, Top, Main, Index

Retrieve values of multiple fields from a native struct in memory.

OBJECT getnativefields! pointer fieldnames ?index?

Parameters

`pointer`	Safe or unsafe pointer to memory allocated for the C struct. Must be tagged with the struct name.
`fieldnames`	List of field names.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Return value

Returns a list of field values in the same order as $fieldnames

info [::cffi::Struct]Struct, Top, Main, Index

Returns a dictionary containing information about the struct layout

OBJECT info ?args?

Parameters

-vlacount VLACOUNT Number of elements in variable size array.

Description

The returned dictionary has the following fields:

Size	Size of the struct.
Alignment	Struct alignment.
Fields	Dictionary of fields keyed by field name. The value is another nested dictionary with keys Size, Offset, and Definition containing the size, offset in struct, and type definition of the field.

The option -vlacount must be specified if the struct contains a field that is a variable length array (VLA) or a nested struct that contains a VLA. VLACOUNT is then length of that array.

Return value

Returns a dictionary containing information about the struct layout

name [::cffi::Struct]Struct, Top, Main, Index

Returns the name of the struct.

OBJECT name

Description

Note the name of the struct is different from the name of the object name.

Return value

Returns the name of the struct.

new [::cffi::Struct]Struct, Top, Main, Index

Allocates and initializes a native struct in memory.

OBJECT new ?initval?

Parameters

initval Initial value for the struct as a dictionary mapping field names to values. Optional, default "".

Description

If no argument is supplied or fields are missing, defaults from the struct definition are used for initialization. An error is raised if any fields are not defaulted unless the -clear option was specified for the Struct. In that case missing fields without defaults are filled with zeroes.

For fields containing variable length arrays, the field holding the length of the array must be explicitly specified and cannot be defaulted.

The allocated memory must be freed by calling the free method for the struct.

Return value

Returns a safe pointer to the allocated memory tagged with the struct name.

setnative [::cffi::Struct]Struct, Top, Main, Index

Sets the value of a field in a native structure in memory

OBJECT setnative pointer fieldname value ?index?

Parameters

`pointer`	Safe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`fieldname`	Name of the field.
`value`	Value to store in the field.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

The field being set must not be a variable sized field, or field holding a count for a variable sized field; otherwise, an error is raised.

setnative! [::cffi::Struct]Struct, Top, Main, Index

Sets the value of a field in a native structure in memory

OBJECT setnative! pointer fieldname value ?index?

Parameters

`pointer`	Safe or unsafe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`fieldname`	Name of the field.
`value`	Value to store in the field.
`index`	If present, `$pointer` is interpreted as pointing to an array of structs and this is the index into that array. For variable sized structs `index` must be `0` or unspecified. Optional, default `0`.

Description

The field being set must not be a variable sized field, or field holding a count for a variable sized field; otherwise, an error is raised.

size [::cffi::Struct]Struct, Top, Main, Index

Returns the size of the struct.

OBJECT size ?args?

Parameters

-vlacount VLACOUNT Number of elements in variable size array.

Description

The option -vlacount must be specified if the struct contains a field that is a variable length array (VLA) or a nested struct that contains a VLA. VLACOUNT is then length of that array.

Return value

Returns the size of the struct.

tobinary [::cffi::Struct]Struct, Top, Main, Index

Encodes the Tcl representation of a C struct value into a Tcl binary string.

OBJECT tobinary dict_value

Parameters

dict_value A Tcl dictionary representation of a C struct value.

Return value

Returns the binary string containing the native C struct.

tonative [::cffi::Struct]Struct, Top, Main, Index

Writes the Tcl dictionary representation of a C struct value to memory in native form.

OBJECT tonative pointer initializer ?index?

Parameters

`pointer`	Safe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`initializer`	The Tcl dictionary value.
`index`	The index position at which the struct is to be written. Note this interpreted as an index into an array of structs, not as a byte offset into memory. Optional, default `0`.

Description

The method raises an error if the struct is variable size.

tonative! [::cffi::Struct]Struct, Top, Main, Index

Writes the Tcl dictionary representation of a C struct value to memory in native form.

OBJECT tonative! pointer initializer ?index?

Parameters

`pointer`	Safe or unsafe pointer to memory allocated for the C struct or array. Must be tagged with the struct name.
`initializer`	The Tcl dictionary value.
`index`	The index position at which the struct is to be written. Note this interpreted as an index into an array of structs, not as a byte offset into memory. Optional, default `0`.

Description

The method raises an error if the struct is variable size.

Union [::cffi]Top, Main, Index

Method summary

constructor	Constructor for the class.
decode	Returns a field from a native union.
describe	Returns a human-readable description of the C union definition.
encode	Returns a union in native form with the specified field value.
info	Returns a dictionary containing information about the info layout.
name	Returns the name of the struct.
size	Returns the size of the union.

constructor [::cffi::Union]Union, Top, Main, Index

Constructs a script level object that maps to a C union definition.

Union create OBJNAME definition ?args?
Union new definition ?args?

Parameters

`definition`	Defines the layout and type of the C struct fields.
`args`	Options. Currently the only option is `-clear`

Description

The created object can be used to manipulate native C unions.

The $definition argument is a dictionary mapping field names to the corresponding types. This has the same syntax as Structs.

If the -clear option is present, the memory of unions of this type is cleared before the field values are initialized.

decode [::cffi::Union]Union, Top, Main, Index

Returns a field from a native union.

OBJECT decode field uvalue

Parameters

`field`	The field within the union that should be retrieved.
`uvalue`	The opaque union in native form.

Return value

Returns a field from a native union.

describe [::cffi::Union]Union, Top, Main, Index

Returns a human-readable description of the C union definition.

OBJECT describe

Description

This is primarily for debugging and troubleshooting purposes.

Return value

Returns a human-readable description of the C union definition.

encode [::cffi::Union]Union, Top, Main, Index

Returns a union in native form with the specified field value.

OBJECT encode field value

Parameters

`field`	The field within the union that should be set.
`value`	The value of the field.

Return value

Returns a union in native form with the specified field value.

info [::cffi::Union]Union, Top, Main, Index

Returns a dictionary containing information about the info layout

OBJECT info

Description

The returned dictionary has the following fields:

Size	Size of the struct.
Alignment	Struct alignment.
Fields	Dictionary of fields keyed by field name. The value is another nested dictionary with keys Size, Offset, and Definition containing the size, offset in struct, and type definition of the field.

Other fields may be present and should be ignored.

Return value

Returns a dictionary containing information about the info layout

name [::cffi::Union]Union, Top, Main, Index

Returns the name of the struct.

OBJECT name

Description

Note the name of the struct may be different from the name of the object command.

Return value

Returns the name of the struct.

size [::cffi::Union]Union, Top, Main, Index

Returns the size of the union.

OBJECT size

Return value

Returns the size of the union.

Wrapper [::cffi]Top, Main, Index

Method summary

constructor	Constructor for the class.
destructor	Destructor for the class.
addressof	Returns the address of a symbol from the loaded library.
function	Creates a Tcl command to invoke a C function in the loaded library.
functions	Creates Tcl commands for multiple C functions within the loaded library.
path	Returns the file system path for the wrapped library or image wrapped by the object.
stdcall	Creates a Tcl command to invoke a C function that uses the `__stdcall` calling convention from the loaded library..
stdcalls	Creates Tcl commands for multiple C functions within the loaded library that all use the `__stdcall` calling convention.

constructor [::cffi::Wrapper]Wrapper, Top, Main, Index

Wraps a shared library / DLL, loading it in the process.

Wrapper create OBJNAME path
Wrapper new path

Parameters

path Path to the shared library.

Description

It is strongly recommended that the path to the shared library be specified as an absolute path. Otherwise, it is located in a system-specific manner involving operating system version, environment variables, registry settings (on Windows), phase of the moon etc.. This is not advisable for both reliability and security reasons.

When no longer needed, the object can be deleted in the usual manner (via rename to an empty string) or by invoking its destroy method.

Return value

Returns the name of the created object.

destructor [::cffi::Wrapper]Wrapper, Top, Main, Index

Destroys the object and releases internal resources.

OBJECT destroy

Description

The managed library may be unloaded if there is nothing else holding a reference to it.

addressof [::cffi::Wrapper]Wrapper, Top, Main, Index

Returns the address of a symbol from the loaded library.

OBJECT addressof symbol

Parameters

symbol Name of the symbol.

Description

The command will raise an error if the symbol is not found.

Return value

Returns the address of a symbol from the loaded library.

function [::cffi::Wrapper]Wrapper, Top, Main, Index

Creates a Tcl command to invoke a C function in the loaded library.

OBJECT function fnname fntype parameters

Parameters

`fnname`	Name of the function and optionally, Tcl command.
`fntype`	The type definition for the return value from the function.
`parameters`	List of alternating parameter name and type definitions.

Description

The command creates a Tcl command corresponding to a C function contained in the library. The function must be one that follows the default C calling convention (See Calling conventions).

The $fnname argument is a one or two element list, the first being the name of the C function and the second, if present, being the name of the corresponding Tcl command. The latter defaults to the former if unspecified. Unless fully qualified, the command is created in the namespace from which it is called.

The return type of the C function is specified through the $fntype argument which should be a type declaration. See syntax.

The $parameters argument is a list of alternating parameter names and type declarations that describe the parameters of the C function. The parameter name is only used to construct error messages while the latter determines how arguments are converted and passed to the C function. See syntax.

The return type as well as parameter type declarations may have annotations that control semantics and behavior with respect to how values are passed and converted between Tcl and C. See Functions for details of these.

The command will raise an error if the function identified by $cname is not found in the loaded DLL.

Return value

Returns the name of the created Tcl command.

functions [::cffi::Wrapper]Wrapper, Top, Main, Index

Creates Tcl commands for multiple C functions within the loaded library.

OBJECT functions fnlist ?args?

Parameters

`fnlist`	List of function definitions.
`-ignoremissing`	Do not raise an error if a function is not found.

Description

This is a wrapper around the function method that provides some syntactic sugar for defining multiple functions. The $fnlist argument is a flat (not nested) list of function name, return type and parameter list in the same form as described for the function method.

If a function is not found, the command will raise an error but those functions that are found will be defined. The error can be completely suppressed with the -ignoremissing option.

If the function name element is #, the triple is ignored, effectively being considered a comment.

path [::cffi::Wrapper]Wrapper, Top, Main, Index

Returns the file system path for the wrapped library or image wrapped by the object.

OBJECT path

Description

The returned path may be or may not be normalized and may be in native form or Tcl's canonical form. If no path argument was provided to the constructor, an empty string may be returned on some platforms.

Return value

Returns the file system path for the wrapped library or image wrapped by the object.

stdcall [::cffi::Wrapper]Wrapper, Top, Main, Index

Creates a Tcl command to invoke a C function that uses the __stdcall calling convention from the loaded library..

OBJECT stdcall fnname fntype parameters

Parameters

`fnname`	Name of the function and optionally, Tcl command.
`fntype`	The type definition for the return value from the function.
`parameters`	List of alternating parameter name and type definitions.

Description

The command creates a Tcl command corresponding to a C function contained in the library. The function must be one that follows the __stdcall calling convention (See Calling conventions). The only platform where this differs from the C calling convention is 32-bit Windows. On other platforms, this method is a synonym for function.

See function for other details.

Return value

Returns the name of the created Tcl command.

stdcalls [::cffi::Wrapper]Wrapper, Top, Main, Index

Creates Tcl commands for multiple C functions within the loaded library that all use the __stdcall calling convention.

OBJECT stdcalls fnlist ?args?

Parameters

`fnlist`	List of function definitions.
`-ignoremissing`	Do not raise an error if a function is not found.

Description

This is a wrapper around the stdcall method that provides some syntactic sugar for defining multiple functions. The $fnlist argument is a flat (not nested) list of function name, return type and parameter list in the same form as described for the stdcall method.

If a function is not found, the command will raise an error but those functions that are found will be defined. The error can be completely suppressed with the -ignoremissing option.

If the function name element is #, the triple is ignored, effectively being considered a comment.

::cffiTop, Main, Index

CommandsTop, Main, Index

alias [::cffi]Top, Main, Index

Description

alias body [::cffi]Top, Main, Index

Parameters

Description

Return value

alias clear [::cffi]Top, Main, Index

alias define [::cffi]Top, Main, Index

Parameters

Description

alias delete [::cffi]Top, Main, Index

Parameters

Description

alias list [::cffi]Top, Main, Index

Parameters

Description

Return value

alias load [::cffi]Top, Main, Index

Parameters

Description

arena [::cffi]Top, Main, Index

Description

arena allocate [::cffi]Top, Main, Index

Parameters

Description

Return value

See also

arena new [::cffi]Top, Main, Index

Parameters

Description

Return value

See also

arena popframe [::cffi]Top, Main, Index

Description

arena pushframe [::cffi]Top, Main, Index

Parameters

Description

Return value

See also

call [::cffi]Top, Main, Index

Parameters

Description

Return value

callback [::cffi]Top, Main, Index

Description

callback free [::cffi]Top, Main, Index

Parameters

callback new [::cffi]Top, Main, Index

Parameters

Description

Return value

enum [::cffi]Top, Main, Index

Description

enum alias [::cffi]Top, Main, Index

Parameters

Description

Return value

enum clear [::cffi]Top, Main, Index

enum define [::cffi]Top, Main, Index

Parameters

Description

Return value

enum delete [::cffi]Top, Main, Index

Parameters

Description

enum flags [::cffi]Top, Main, Index

Parameters

Description

Return value

enum list [::cffi]Top, Main, Index

Parameters

Description

enum mask [::cffi]Top, Main, Index

Parameters

Return value

See also

enum members [::cffi]Top, Main, Index

Parameters