Mercurial > core / lisp/std/alien.lisp

 ;;; std/alien.lisp --- foreign alien friends
 
 ;;; Commentary:
 
 ;; FFI in Lisp is somewhat different than FFI in other host langs. As
 ;; such, we usually refer to our Lispy FFI interfaces inline with the
 ;; CMUCL terminology: alien interfaces.
 
 ;; ref: https://www.sbcl.org/manual/#Foreign-Function-Interface for details
 
 ;; sb-alien is a high-level interface which automatically converts C
 ;; memory pointers to lisp objects and back, but this can be slow for
 ;; large or complex objects.
 
 ;; The lower-level interface is based on System Area Pointers (or
 ;; SAPs), which provide untyped access to foreign memory.
 
 ;; Objects which can't be automatically converted into Lisp values are
 ;; represented by objects of type ALIEN-VALUE.
 
 ;;; Code:
 (uiop:define-package :std/alien
   (:nicknames :alien)
   (:use :sb-vm :sb-ext :sb-c :std/base)
   (:use-reexport :sb-alien)
   (:export
    :copy-c-string
    :clone
    :foreign-int-to-integer :foreign-int-to-bool :bool-to-foreign-int
    :defbytes
    :u1 :u2 :u3 :u4 :u8 :u16 :u24 :u32 :u64 :u128
    :i2 :i3 :i4 :i8 :i16 :i24 :i32 :i64 :i128
    :f16 :f24 :f32 :f64 :f128))
 
 (in-package :alien)
 
 ;; (reexport-from :sb-vm
 ;; 	       :include
 ;; 	       '(:with-pinned-objects :with-pinned-object-iterator :with-code-pages-pinned
 ;; 		 :sanctify-for-execution))
 
 (defun copy-c-string (src dest &aux (index 0))
   (loop (let ((b (sb-sys:sap-ref-8 src index)))
           (when (= b 0)
             (setf (fill-pointer dest) index)
             (return))
           (setf (char dest index) (code-char b))
           (incf index))))
 
 (defun clone-strings (list)
   (with-alien ((x (* (* char))
                   (make-alien (* char) (length list))))
     (unwind-protect
          (labels ((populate (list index function)
                     (if list
                         (let ((array (sb-ext:string-to-octets (car list) :null-terminate t)))
                           (sb-sys:with-pinned-objects (array)
                             (setf (deref x index) (sap-alien (sb-sys:vector-sap array) (* char)))
                             (populate (cdr list) (1+ index) function)))
                         (funcall function))))
            (populate list 0
                      (lambda ()
                        (loop for i below (length list)
                              do (print (cast (deref x i) c-string))))))
       (free-alien x))))
 
 (defun foreign-int-to-integer (buffer size)
   "Check SIZE of int BUFFER. return BUFFER."
   (assert (= size (sb-alien:alien-size sb-alien:int :bytes)))
   buffer)
 
 (defun foreign-int-to-bool (x size)
   (if (zerop (foreign-int-to-integer x size))
       nil
       t))
 
 (defun bool-to-foreign-int (val)
   (if val 1 0))
 
 ;;; Bytes
 (defmacro defbytes (&body bitsets)
   "For each cons-cell in BITSETS, define a new CAR-byte type for each
 member of CDR."
   `(loop for set in ',bitsets
 	 collect
 	 (let* ((ty (car set))
 		(pfx
 		  (cond
 		    ((eq 'signed-byte ty) "I")
 		    ((eq 'unsigned-byte ty) "U")
 		    ((eq 'float ty) "F")
 		    (t (subseq (symbol-name ty) 0 1))))
 		(nums (cdr set))
 		r) ;result
 	   (setf r
 		 (mapc
 		  (lambda (x)
 		    `(deftype ,(symbolicate pfx (format 'nil "~a" x)) ()
 		       (cons ,ty ,x)))
 		       nums))
 	   (cons ty r))))
 
 (defbytes
   (unsigned-byte 1 2 3 4 8 16 24 32 64 128)
   (signed-byte 2 3 4 8 16 24 32 64 128)
   (float 16 24 32 64 128))