use ptrdiff_t, not guesswork

* figl/gl/types.scm (GLintptr, GLsizeiptr): Define as ptrdiff_t from
  recent Guile.  Fixed a bug where this was set to an unsigned type.
  Add note that about non-Mesa platforms.

diff --git a/figl/gl/types.scm b/figl/gl/types.scm
index 4ba5ff1..9b5da2e 100644 (file)
--- a/figl/gl/types.scm
+++ b/figl/gl/types.scm
@@ -81,11 +81,9 @@
             const-GLvoid-**
             void-*))
 
-(define %ptr
-  (case (ffi:sizeof '*)
-    ((4) ffi:uint32)
-    ((8) ffi:uint64)
-    (else (error "unknown pointer size"))))
+;; TODO: Taken from Mesa headers for some types below.  Not clear what
+;; these types are on other platforms.
+(define %ptr ffi:ptrdiff_t)
 
 (define-simple-foreign-type void ffi:void)
 (define-simple-foreign-type GLboolean ffi:uint8)