Ignore:
Timestamp:
Jan 6, 2009, 6:00:06 PM (11 years ago)
Author:
rme
Message:

Additional x8632 FFI details involving structure return and callbacks.

DEFINE-CALLBACK: add hair to recognize when a hidden first argument
will need to be discarded on return. Try to deal with interactions
with the win32 _stdcall case, too. Pass info argument to
DEFINE-CALLBACK-FUNCTION that encodes the arg discard information.

DEFINE-CALLBACK-FUNCTION: pass said info argument to
MAKE-CALLBACK-TRAMPOLINE.

MAKE-CALLBACK-TRAMPOLINE: pack arg discarding information and the
callback index into the value that gets passed to .SPcallback via
the %eax register.

.SPcallback: decode this information, and handle discarding the
appropriate number of args on return.

File:
1 edited

Legend:

Unmodified
Added
Removed
  • trunk/source/level-1/x86-callback-support.lisp

    r11228 r11590  
    1919
    2020#+x8664-target 
    21 (defun make-callback-trampoline (index &optional discard-stack-bytes)
    22   (declare (ignore discard-stack-bytes))
     21(defun make-callback-trampoline (index &optional info)
     22  (declare (ignore info))
    2323  (let* ((p (%allocate-callback-pointer 16))
    2424         (addr #.(subprim-name->offset '.SPcallback)))
     
    4040         
    4141#+x8632-target         
    42 (defun make-callback-trampoline (index &optional (discard-stack-bytes 0))
     42(defun make-callback-trampoline (index &optional info)
    4343  (let* ((p (%allocate-callback-pointer 12))
    4444         (addr #.(subprim-name->offset '.SPcallback)))
     45    ;; If the optional info parameter is supplied, it will contain
     46    ;; some stuff in bits 23 through 31.
     47    ;;
     48    ;; If bit 23 is set, that indicates that the caller will pass a
     49    ;; "hidden" argument which is a pointer to appropriate storage for
     50    ;; holding a returned structure.  .SPcallback will have to discard
     51    ;; this extra argument upon return.
     52    ;;
     53    ;; The high 8 bits denote the number of words that .SPcallback
     54    ;; will have to discard upon return (used for _stdcall on
     55    ;; Windows).  Bit 23 won't be set in this case: we will have
     56    ;; already added in the extra word to discard if that's necessary.
     57    ;;
     58    ;; These bits are be packed into the value that .SPcallback
     59    ;; receives in %eax.  Bits 0 through 22 are the callback index.
     60    (if info
     61      (setf (ldb (byte 23 0) info) index)
     62      (setq info index))
    4563    (setf (%get-unsigned-byte p 0) #xb8 ; movl $n,%eax
    46           (%get-unsigned-byte p 1) (ldb (byte 8 0) index)
    47           (%get-unsigned-byte p 2) (ldb (byte 8 8) index)
    48           (%get-unsigned-byte p 3) (ldb (byte 8 16) index)
    49           (%get-unsigned-byte p 4) (ldb (byte 8 0) (ash (or discard-stack-bytes 0) (- x8632::word-shift)))
     64          (%get-unsigned-byte p 1) (ldb (byte 8 0) info)
     65          (%get-unsigned-byte p 2) (ldb (byte 8 8) info)
     66          (%get-unsigned-byte p 3) (ldb (byte 8 16) info)
     67          (%get-unsigned-byte p 4) (ldb (byte 8 24) info)
    5068          (%get-unsigned-byte p 5) #xff  ; jmp *
    5169          (%get-unsigned-byte p 6) #x24
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