ffi-helper: status

ffi-helper: status

[Matt Wette]

Hi All,

I am working on a ffi-helper: a program that will read in a C dot-h file and generate a Guile dot-scm file which
defines a module to provide hooks into the associated C library.  My goal is to have something to release ~Oct 2017.

I have now been able to compile-ffi the following on my Mac. There is some non-standard C syntax in sys/cdefs.h
that is driving me crazy, but I have a hack around it (see inc-help below).  I’m sure there are numerous bugs.

(define-ffi-module (cairo cairo)
  #:pkg-config "cairo"
  #:include '("cairo.h"
	      "cairo-pdf.h"
	      "cairo-svg.h"
	      )
  #:inc-help (cond
	      ((string-contains %host-type "darwin")
	       '(("__builtin" "__builtin_va_list=void*")
		 ("sys/cdefs.h" "__DARWIN_ALIAS(X)=")))
	      (else '()))

  ;; the following are bent pipe to scm-module
  #:export (make-cairo-unit-matrix)
  )

(define (make-cairo-unit-matrix)
  (make-cairo_matrix_t #(1.0 0.0 0.0 1.0 0.0 0.0)))


Some of the other Cairo headers (e.g., cairo-ft.h) give me problems with the rat’s nest under /usr/include.

However, the above generates 397 FFI declarations into a cairo.scm file which is about 6000 lines long.  I’m not 
sure if I want to start testing this code or start converting suggestions and have guile-users do some testing.  

Matt

P.S.  Here is some sample code from the auto-generated file cairo/cairo.scm.  
Notice that the helper includes the original C declarations as comments.

;; typedef struct _cairo_device cairo_device_t;
(define-fh-pointer-type cairo_device_t*)

;; union _cairo_path_data_t {
;;   struct {
;;     cairo_path_data_type_t type;
;;     int length;
;;   } header;
;;   struct {
;;     double x, y;
;;   } point;
;; };
(define cairo_path_data_t-desc
  (bs:union
    (list `(header
             ,(bs:struct
                (list `(type ,cairo_path_data_type_t-desc)
                      `(length ,int))))
          `(point ,(bs:struct (list `(y ,double) `(x ,double)))))))
(export cairo_path_data_t-desc)
(define-fh-bytestructure-type/p cairo_path_data_t cairo_path_data_t-desc)
(define union-_cairo_path_data_t cairo_path_data_t)

;; typedef enum _cairo_path_data_type {
;;   CAIRO_PATH_MOVE_TO,
;;   CAIRO_PATH_LINE_TO,
;;   CAIRO_PATH_CURVE_TO,
;;   CAIRO_PATH_CLOSE_PATH,
;; } cairo_path_data_type_t;
(define-fh-enum-type cairo_path_data_type_t
  '((CAIRO_PATH_MOVE_TO . 0)
    (CAIRO_PATH_LINE_TO . 1)
    (CAIRO_PATH_CURVE_TO . 2)
    (CAIRO_PATH_CLOSE_PATH . 3))
  )

;; typedef void (*cairo_destroy_func_t)(void *data);
(define (wrap-cairo_destroy_func_t proc) ;; => pointer
 (ffi:procedure->pointer ffi:void proc (list '*))
 )
(export wrap-cairo_destroy_func_t)

;; cairo_status_t cairo_device_set_user_data(cairo_device_t *device, const 
;;     cairo_user_data_key_t *key, void *user_data, cairo_destroy_func_t 
;;     destroy);
(define cairo_device_set_user_data
  (let ((~f (ffi:pointer->procedure
              ffi:int
              (lib-func "cairo_device_set_user_data")
              (list '* '* '* '*))))
    (lambda (device key user_data destroy)
      (let ((~device (unwrap-cairo_device_t* device))
            (~key (unwrap-cairo_user_data_key_t* key))
            (~user_data (unwrap~pointer user_data))
            (~destroy (unwrap-cairo_destroy_func_t destroy)))
        (wrap-cairo_status_t
          (~f ~device ~key ~user_data ~destroy))))))
(export cairo_device_set_user_data)

Re: ffi-helper: status

[Matt Wette]

> On Jul 7, 2017, at 5:18 PM, Matt Wette <matt.wette@gmail.com> wrote:
> However, the above generates 397 FFI declarations into a cairo.scm file which is about 6000 lines long.  I’m not 
> sure if I want to start testing this code or start converting suggestions and have guile-users do some testing.  

That is, for this example, I no longer run into declarations which my code says “failed,” indicating that it didn’t know what to do with the declaration.

I already notice that the function types converters should be called “unwrap” and that they should be called by the procedure interface.  I am going to start playing with cairo_set_user_data to see if passed procedures work. 

Re: ffi-helper: status

[Matt Wette]

> On Jul 7, 2017, at 5:31 PM, Matt Wette <matt.wette@gmail.com> wrote:
> 
> 
>> On Jul 7, 2017, at 5:18 PM, Matt Wette <matt.wette@gmail.com> wrote:
>> However, the above generates 397 FFI declarations into a cairo.scm file which is about 6000 lines long.  I’m not 
>> sure if I want to start testing this code or start converting suggestions and have guile-users do some testing.  
> 
> That is, for this example, I no longer run into declarations which my code says “failed,” indicating that it didn’t know what to do with the declaration.
> 
> I already notice that the function types converters should be called “unwrap” and that they should be called by the procedure interface.  I am going to start playing with cairo_set_user_data to see if passed procedures work. 

Another working demo:

mwette$ guile exam.d/cairo02.scm
d1 called with ((abc . 123) (def . 456))

mwette$ cat exam.d/cairo02.scm
;; exam.d/cairo02.scm

(use-modules (cairo cairo))		; auto-generated from cairo.h etc
(use-modules (ffi-help-rt))		; pointer-to
(use-modules (system foreign))		; string->pointer, pointer<->scm

(define srf (cairo_svg_surface_create (string->pointer "abc.svg") 200.0 200.0))
(define cr (cairo_create srf))

;; typedef struct _cairo_user_data_key {
;;   int unused;
;; } cairo_user_data_key_t;
;;
;; typedef void (*cairo_destroy_func_t)(void *data);
;;
;; cairo_status_t cairo_set_user_data(cairo_t *cr, const cairo_user_data_key_t
;;      *key, void *user_data, cairo_destroy_func_t destroy);

(define k1 (make-cairo_user_data_key_t)) ; make a key
(define v1 '((abc . 123) (def . 456)))	 ; make some data
(define (d1 data)			 ; callback
  (simple-format #t "d1 called with ~S\n" (pointer->scm data)))
	 
(cairo_set_user_data cr (pointer-to k1) (scm->pointer v1) d1)

(cairo_destroy cr)
(cairo_surface_destroy srf)

;; --- last line ---