# NAME Affix - A Foreign Function Interface eXtension # SYNOPSIS ```perl use v5.40; use Affix; # Load a Library my $lib = load_library(libm); # libm.so / msvcrt.dll # Bind a Function # double pow(double x, double y); affix $lib, 'pow', [ Double, Double ] => Double; # Call it say pow( 2.0, 10.0 ); # 1024 # Allocate 1KiB of raw memory my $ptr = Affix::malloc(1024); # Write raw data to the pointer Affix::memcpy( $ptr, 'test', 4 ); # Poiner arithmetic creates a new reference (doesn't modify original) my $offset_ptr = Affix::ptr_add( $ptr, 12 ); Affix::memcpy( $offset_ptr, 'test', 4 ); # Inspect memory with a hex dump to STDOUT Affix::dump( $ptr, 32 ); # Release the memory Affix::free($ptr); ``` # DESCRIPTION **Affix** is a high-performance Foreign Function Interface (FFI) for Perl. It allows you to load dynamic libraries (DLLs, shared objects) and call their functions natively without writing XS code or configuring a C compiler. It distinguishes itself from other FFI solutions by using [**infix**](https://github.com/sanko/infix/), a custom lightweight JIT engine. When you bind a function, Affix generates machine code at runtime (a 'trampoline') to handle the argument marshalling. This results in significantly lower overhead than generic FFI wrappers that rely on dynamic dispatch per-call. # EXPORTS Affix exports standard types (`Int`, `Double`, etc.) and core functions (`affix`, `wrap`, `load_library`) by default. You can control imports using tags: ```perl use Affix qw[:all]; # Import everything use Affix qw[:lib]; # Library helpers (libc, libm, load_library...) use Affix qw[:memory]; # malloc, free, memcpy, cast, dump... use Affix qw[:pin]; # Variable binding (pin, unpin) use Affix qw[:types]; # Types only (Int, Struct, Pointer...) ``` # Core API Affix's API is designed to be expressive. Let's start at the beginning with the eponymous `affix( ... )` function. ## `affix( ... )` Attaches a symbol from a library to a named perl subroutine in the current namespace. ```perl # Standard: Load from library affix $lib, 'pow', [ Double, Double ] => Double; # Rename: Load 'pow', install as 'power' affix $lib, [ pow => 'power' ], [ Double, Double ] => Double; # Raw pointer: Bind a specific memory address (vtables, JIT, dlsym, etc.) affix undef, [ $ptr => 'my_func' ], [Int] => Void; ``` Parameters: - `$lib` A library handle returned by `[load_library( $path )](#load_library-path)`, a path string, or `undef` (searches the main executable/process). - `$symbol_name` The name of the function to find. Pass an array list (`['real_name', 'alias']`) to rename it in Perl. - `$parameters` An array reference of argument types. See [Types](#types) for the full list. - `$return` A single return type for the function. On success, `affix( ... )` installs the subroutine and returns the generated code reference. ## `wrap( ... )` Creates a wrapper around a given symbol and returns it as an anonymous `CODE` reference. ```perl # From library my $pow = wrap $lib, 'pow', [ Double, Double ] => Double; # Call the function my $result = $pow->( 2, 5 ); # From a raw pointer # Note: Library argument is undef my $func = wrap undef, $ptr, [Int] => Void; ``` Arguments are nearly identical to `[affix( ... )](#affix)` except you cannot provide an alias for the function name. ## `pin( ... )` ```perl my $scalar; # Bind $scalar to the global integer variable 'errno' in libc pin $scalar, libc(), 'errno', Int; $scalar = 0; # Writes to C memory sysopen( ... ); say $scalar; # Reads from C memory ``` Variables exported by a library (global/extern variables) can be accessed using `pin`. Reading the scalar reads the memory; writing to it writes to the memory. Parameters: - `$var` The scalar to bind. - `$lib` The library handle. - `$symbol` Name of the exported variable. - `$type` The type of data the variable contains. ## `unpin( ... )` ``` unpin $errno; ``` Removes the magic applied by `pin( ... )` to a variable. The variable retains its last value but is no longer linked to C memory. ## `typedef( ... )` ```perl typedef MyType => Struct[ name => String, age => Int ]; # Now use it in signatures affix $lib, 'func', [ MyType() ] => Void; ``` Registers a named type alias. This is required for: - 1. **Recursive Types**: A struct that contains a pointer to itself. - 2. **Reusability**: Defining a complex signature once and using it in multiple functions. - 3. **Smart Enums**: Generating Perl constants in your package. ## `coerce( $type, $value )` Used primarily with [Variadic Functions](#variadic-functions-varargs). It wraps a value with type information so Affix knows how to marshal it when no compile-time signature is available. ``` # Hint that we are passing a Float, not a Double coerce( Float, 1.5 ); ``` ## `get_last_error_message( )` Returns a string describing the most recent error that occurred during library loading or symbol lookup. # Library Utilities Locating libraries on different platforms can be tricky. These utilities help you load and manage dynamic libraries. They are exported by default but may be imported specifically with the `:lib` tag. ## `load_library( $path )` ```perl my $lib = load_library( 'user32.dll' ); ``` Locates and loads a dynamic library, returning an opaque (`Affix::Lib`) handle. If you pass a name without an extension (e.g., 'm'), Affix applies platform-specific prefixes/suffixes (e.g., 'libm.so', 'libm.dylib', 'm.dll') and searches standard system paths. ## `locate_lib( $name, [$version] )` ```perl my $path = locate_lib('ssl', '1.1'); ``` Searches system paths (`LD_LIBRARY_PATH`, `PATH`, `DYLD_LIBRARY_PATH`, etc.) and returns the full absolute path to the library file without loading it. ## `find_symbol( $lib, $name )` Returns the raw memory address (as an integer) of a symbol. Useful if you need to pass a function pointer **value** to C, rather than calling it. ## `libc()` / `libm()` Helpers returning handles to the standard C library and math library. # Memory Management Affix uses **pins** to manage raw memory. A pin is a magical scalar reference holding a memory address and type information. ## `malloc( $size )` ```perl my $ptr = malloc( 1024 ); ``` Allocates `$size` bytes of uninitialized memory. Returns a `Pointer[Void]` pin. ## `calloc( $num, $size_or_type )` ```perl my $array = calloc( 10, Int ); ``` Allocates memory for an array of `$count` elements and initializes them to zero. You may pass a Type object (like `Int`) or a raw size in bytes. ## `realloc( $ptr, $new_size )` ``` $ptr = realloc( $ptr, $new_size ); ``` Resizes the memory pointed to by `$ptr`. Returns the new pointer (the original pin is updated automatically). ## `free( $ptr )` ``` free( $ptr ); ``` Releases memory allocated by Affix. **Note:** Only use this on memory allocated by `malloc`, `calloc`, or `strdup`. Do not attempt to free pointers returned by C libraries unless the library documentation explicitly says you own that memory. ## `cast( $ptr, $type )` ```perl my $void = malloc(4); my $int = cast( $void, Int ); # Read immediate value my $int_p = cast( $void, Pointer[Int] ); # Return new Pin ``` Reinterprets a pointer. - **To value** (`Int`, etc.): Reads the memory immediately and returns a Perl scalar. - **To reference** (`Pointer[Int]`): Returns a new pin aliasing the memory. Dereferencing it (`$$pin`) reads/writes the value. ## `own( $ptr, [$bool] )` ``` own( $ptr, $bool ); ``` Controls lifecycle management. - `own($p, 1)`: Perl owns the memory; \`free()\` is called when \`$p\` goes out of scope. - `own($p, 0)`: Perl releases ownership. Useful when handing memory off to a C function. ## `address( $ptr )` Returns the virtual memory address of the pointer as a `UInt64`. ## Pointer Arithmetic & Utilities - `ptr_add( $ptr, $offset )` Returns a new unmanaged pin offset by `$bytes`. If `$ptr` is an array type, it decays to a pointer type. - `ptr_diff( $ptr1, $ptr2 )` Returns the difference in bytes (`$ptr1 - $ptr2`). - `is_null( $ptr )` Returns true if the pointer is `NULL` (`0x0`). - `strdup( $string )` Allocates memory and copies the Perl string (plus `NULL` terminator) into it. - `strnlen( $ptr, $maxlen )` Safe string length calculation. ## Raw Memory Operatoins Standard C memory operations are available for high-performance manipulation of pins. - `memchr( $ptr, $ch, $count )` - `memcmp( $lhs, $rhs, $count )` - `memset( $dest, $ch, $count )` - `memcpy( $dest, $src, $count )` - `memmove( $dest, $src, $count )` ## `dump( $ptr, $length )` Prints a hex dump of the memory at `$ptr` to `STDOUT`. # Introspection ## `sizeof( $type )` ```perl my $size = sizeof( Int ); my $size_rect = sizeof( Struct[ x => Int, y => Int ] ); ``` Returns the size, in bytes, of a Type object. ## `offsetof( $struct_type, $field_name )` ```perl my $struct = Struct[ name => String, age => Int ]; my $offset = offsetof( $struct, 'age' ); ``` Returns the byte offset of a field within a Struct or Union. ## `alignof( $type )` Returns the required alignment bytes for a Type. ## `types()` Returns a list of all named types currently registered in the system. # Types Affix signatures are built using these helper functions ```perl # Example Signature [ Int, String ] => Void ``` ## Primitive Types Primitives map to native C types.
TypeDescription
VoidReturns nothing
BoolMapped to Perl true/false
Charsigned char (8-bit usually)
UCharunsigned char
SCharExplicitly signed char
Shortsigned short
UShortunsigned short
Intsigned int (platform native, usually 32-bit)
UIntunsigned int
Longsigned long (32-bit on Win64, 64-bit on Linux64)
ULongunsigned long
LongLongsigned long long (guaranteed 64-bit)
ULongLongunsigned long long
Float32-bit float
Double64-bit float
LongDoublePlatform specific (80-bit or 128-bit)
Size_tsize_t
SSize_tssize_t
### Explicit Width Types For precise control, use these types which are guaranteed to have specific bit widths across all platforms: ``` Int8, UInt8 Int16, UInt16 Int32, UInt32 Int64, UInt64 Int128, UInt128 (Passed as Decimal Strings) ``` 128-bit integers, if supported by the compiler, must be passed as strings to/from Perl. ## Pointers Pointers are the glue of C. Affix provides distinct ways to handle them based on intent. - Basic Pointers (`Pointer[Type]`) When a function expects `int*` or `double*`, pass a **reference to a scalar**. ```perl # C: void split_float(double val, int* whole, double* frac); affix $lib, 'split_float', [ Double, Pointer[Int], Pointer[Double] ] => Void; my ($whole, $frac); split_float( 3.14, \$whole, \$frac ); ``` Affix automatically: - 1. Allocates temporary memory. - 2. Copies the Perl value into it (if defined). - 3. Passes the pointer to C. - 4. Copies the result back into your Perl scalar after the call. - Strings (`String` vs `Pointer[Char]`) - **`String`**: Use this for `const char*` (input strings). Affix copies the Perl string to a temporary C buffer. - **`Pointer[Char]`**: Use this for mutable strings `char*`. You must ensure the scalar passed has enough pre-allocated capacity (e.g. using `"\0" x 1024`). - Void Pointers (`Pointer[Void]`) Used for opaque handles or generic data. - Pass `undef` to send `NULL`. - Pass a reference `\$scalar` to send the address of that scalar. - Pass a **Pin** (from `malloc` or `cast`) to pass that memory address directly. ### Pins (Managed Pointers) For manual memory management, use `malloc`, `calloc`, or `cast`. These return **Pins**. A Pin is a reference to a scalar holding the memory address, blessed with magic. ```perl my $ptr = malloc(1024); # Allocate 1024 bytes my $view = cast($ptr, Int); # Treat it as an integer $$view = 123; # Write 123 to the memory free($ptr); # Free it manually (optional, GC handles it otherwise) ``` ## Special Types - `Buffer` Passes a pointer to the raw string buffer of a Perl scalar. Useful for "Zero-Copy" or "Direct-Write" C functions that populate a buffer. ```perl # C: void get_data(char *buf, int len); affix $lib, 'get_data', [ Buffer, Int ] => Void; my $buf = "\0" x 1024; # Pre-allocate get_data($buf, 1024); ``` **Warning:** The scalar must be writable and have sufficient pre-allocated capacity. - `File` Represents the standard C `FILE` structure. Use `Pointer[File]` to map a Perl filehandle (Glob or IO object) to `FILE*`. ```perl affix $lib, 'fprintf', [ Pointer[File], String ] => Int; open my $fh, '>', 'log.txt'; fprintf($fh, "Hello from Affix!"); ``` - `PerlIO` Represents the internal `PerlIO` structure. Use `Pointer[PerlIO]` when the C function expects `PerlIO*`. - `SockAddr` Safe marshalling for packed socket addresses (e.g. from `Socket::pack_sockaddr_in`). Passed to C as `struct sockaddr*`. - `String` Alias for `const char*`. Affix automatically handles UTF-8 encoding (Perl to C) and decoding (C to Perl). - `StringList` Maps a Perl Array Reference of strings (`[ "a", "b" ]`) to a null-terminated `char**` array (common in C APIs like `execve` or `main(argc, argv)`). ```perl affix $lib, 'process_args', [ StringList ] => Int; process_args( [ "arg1", "arg2" ] ); ``` - `SV` The raw Perl Interpreter Object (`SV`). Use this if you are writing a function that manipulates Perl internals directly. Note that this must always be a pointer: `Pointer[SV]`. - `WString` Alias for `const wchar_t*`. Affix handles the complexity of UTF-16 (Windows) vs UTF-32 (Linux/macOS) and Surrogate Pairs automatically. ## Aggregates ### Structs Structs are the bread and butter of C APIs. In Affix, they map to **Perl Hash References**. ```perl # C: typedef struct { int x; int y; } Point; # void draw_line(Point a, Point b); # Define the type (recommended for reuse) typedef Point => Struct [ x => Int, y => Int ]; # Bind the function affix $lib, 'draw_line', [ Point, Point ] => Void; # Call with HashRefs draw_line( { x => 0, y => 0 }, { x => 100, y => 100 } ); ``` **Nested Structs:** Affix handles deep structures automatically. ```perl typedef Rect => Struct [ top_left => Point, bottom_right => Point, color => Int ]; draw_rect({ top_left => { x => 10, y => 10 }, bottom_right => { x => 50, y => 50 }, color => 0xFF0000 }); ``` ### Unions Maps to Perl hash references with a single key. ```perl # C: union Event { int key_code; float pressure; }; typedef Event => Union [ key_code => Int, pressure => Float ]; # Pass an integer handle_event( { key_code => 27 } ); # Pass a float handle_event( { pressure => 0.5 } ); ``` - `Packed [ $align, $aggregate ]` Defines a struct with specific byte alignment (e.g. `#pragma pack(1)`). ```perl Packed [ 1, Struct[ name => Pointer[Char], # ...etc. ] ]; ``` ## Working with Arrays - **Fixed-Size Arrays (`Array[Type, N]`)** Fixed-size C arrays are mapped to Perl Array References. Affix handles the decay to pointers and automatically writes back changes to your Perl array. ```perl # C: void process_matrix(int matrix[9]); affix $lib, 'process_matrix', [ Array[Int, 9] ] => Void; # Pass a reference to a Perl array process_matrix( [1..9] ); ``` - **Binary Data** For arrays of bytes (`Array[UChar]` or `Array[UInt8]`), Affix treats the data as a raw binary blob. Dereferencing a Pin of this type yields a binary string, reading exactly the number of bytes specified. For arrays of characters (`Array[Char]` or `Array[SInt8]`), Affix treats the data as a C String, reading until the first null terminator or the array limit. ## SIMD Vectors Vectors (e.g. `__m128` on x86, `float32x4_t` on ARM) are first-class types in Affix. You can interact with them in two ways: - 1. **Array References**: Simplest to read and write. - 2. **Packed Strings**: Highest performance (avoids marshalling overhead). ```perl # C: typedef float v4f __attribute__((vector_size(16))); # v4f add_vecs(v4f a, v4f b); affix $lib, 'add_vecs', [ Vector[4, Float], Vector[4, Float] ] => Vector[4, Float]; # Option 1: Array References (Convenient) my $res = add_vecs( [1, 2, 3, 4], [10, 20, 30, 40] ); # $res is [11.0, 22.0, 33.0, 44.0] # Option 2: Packed Strings (Fast) # Useful for tight loops, graphics, or physics math my $packed_a = pack('f4', 1.0, 2.0, 3.0, 4.0); my $packed_b = pack('f4', 10.0, 20.0, 30.0, 40.0); # Pass binary strings directly my $res_ref = add_vecs( $packed_a, $packed_b ); ``` ## Enumerations ```perl typedef Status => Enum [ [ OK => 0 ], 'ERROR', # Auto-increments to 1 [ FLAG_A => 1 << 0 ], # Bit shifting [ FLAG_B => '1 << 1' ], # String expression [ FLAG_C => 'FLAG_B << 1' ] # References previous keys ]; ``` Defines a C enum backed by an integer. - **Constants**: `typedef` installs constants (like `OK`) into your package. - **Dualvars:** Values returned from C are dual-typed. `OK` behaves as the integer `0` in numeric operations, but prints as the string `"OK"`. - **Calculated Values:** You can use string expressions to define values. These are evaluated at definition time. ## Variadic Functions (VarArgs) Affix supports C functions that take a variable number of arguments, like `printf`. ```perl # C: int printf(const char* format, ...); affix libc, 'printf', [ String, VarArgs ] => Int; ``` When calling a variadic function, Affix performs dynamic type inference at runtime for the extra arguments: - Perl Integers -> `int64_t` - Perl Floats -> `double` (Standard C promotion rules) - Perl Strings -> `char*` ``` printf("Hello %s, count is %d\n", "World", 123); ``` ### Hinting Types with `coerce()` Sometimes standard inference isn't enough (e.g., passing a `float` instead of `double`, or passing a Struct by value). Use `coerce($type, $value)` to explicitly hint the type. ```perl # Passing a struct by value to a variadic function typedef Point => Struct [ x=>Int, y=>Int ]; my $p = { x => 10, y => 20 }; # Without coerce(), $p would likely be treated as an error or generic pointer my_variadic_func( "Point: %P", coerce( Point(), $p ) ); ``` ## Callbacks You can pass Perl subroutines to C functions that expect function pointers. ```perl # C: void set_handler( void (*callback)(int status, const char* msg) ); affix $lib, 'set_handler', [ Callback[ [Int, String] => Void ] ] => Void; set_handler(sub ($status, $msg) { say "Received status $status: $msg"; }); ``` **Note:** The callback is valid only as long as the C function holds onto it. If the C library stores the function pointer globally, ensure your Perl code keeps the reference alive if necessary (though Affix handles the trampoline lifecycle automatically for the duration of the call). # Utilities ## `errno()` ```perl my $err = errno(); die "Error $err: " . int($err); ``` Access the `errno` (Linux/Unix) or `GetLastError` (Windows) from the most recent FFI call. This must be called immediately after the function invokes to ensure accuracy. The return value is a **dualvar**: - **Numeric context**: Returns the integer error code. - **String context**: Returns the human-readable system error message (via `strerror` or `FormatMessage`). ## `sv_dump( $sv )` Dumps the internal flags and structure of a Perl `SV`. # EXAMPLES See [The Affix Cookbook](https://github.com/sanko/Affix.pm/discussions/categories/recipes) for comprehensive guides to using Affix. # SEE ALSO [FFI::Platypus](https://metacpan.org/pod/FFI%3A%3APlatypus), [C::DynaLib](https://metacpan.org/pod/C%3A%3ADynaLib), [XS::TCC](https://metacpan.org/pod/XS%3A%3ATCC), [C::Blocks](https://metacpan.org/pod/C%3A%3ABlocks) All the heavy lifting is done by [infix](https://github.com/sanko/infix), my JIT compiler and type introspection engine. # AUTHOR Sanko Robinson # COPYRIGHT Copyright (C) 2023-2026 by Sanko Robinson. This library is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0.