;;; This file contains the PPC specific runtime stuff.
;;;
(in-package "SB!VM")

(defvar *number-of-signals* 64)
(defvar *bits-per-word* 32)

(define-alien-type os-context-t (struct os-context-t-struct))


;;;; MACHINE-TYPE and MACHINE-VERSION

(defun machine-type ()
  "Returns a string describing the type of the local machine."
  "PowerPC")

(defun machine-version ()
  "Returns a string describing the version of the local machine."
  "who-knows?")



;;;; FIXUP-CODE-OBJECT

(defun fixup-code-object (code offset fixup kind)
  (declare (type index offset))
  (unless (zerop (rem offset n-word-bytes))
    (error "Unaligned instruction?  offset=#x~X." offset))
  (sb!sys:without-gcing
   (let ((sap (truly-the system-area-pointer
			 (%primitive sb!kernel::code-instructions code))))
     (ecase kind
       (:b
	(error "Can't deal with CALL fixups, yet."))
       (:ba
	(setf (ldb (byte 24 2) (sap-ref-32 sap offset))
	      (ash fixup -2)))
       (:ha
	(let* ((h (ldb (byte 16 16) fixup))
	       (l (ldb (byte 16 0) fixup)))
	  ; Compensate for possible sign-extension when the low half
	  ; is added to the high.  We could avoid this by ORI-ing
	  ; the low half in 32-bit absolute loads, but it'd be
	  ; nice to be able to do:
	  ;  lis rX,foo@ha
	  ;  lwz rY,foo@l(rX)
	  ; and lwz/stw and friends all use a signed 16-bit offset.
	  (setf (ldb (byte 16 0) (sap-ref-32 sap offset))
		 (if (logbitp 15 l) (ldb (byte 16 0) (1+ h)) h))))
       (:l
	(setf (ldb (byte 16 0) (sap-ref-32 sap offset))
	      (ldb (byte 16 0) fixup)))))))


;;;; "Sigcontext" access functions, cut & pasted from x86-vm.lisp then
;;;; hacked for types.

(define-alien-routine ("os_context_pc_addr" context-pc-addr) (* unsigned-long)
  (context (* os-context-t)))

(defun context-pc (context)
  (declare (type (alien (* os-context-t)) context))
  (int-sap (deref (context-pc-addr context))))

(define-alien-routine ("os_context_register_addr" context-register-addr)
  (* unsigned-long)
  (context (* os-context-t))
  (index int))

(defun context-register (context index)
  (declare (type (alien (* os-context-t)) context))
  (deref (context-register-addr context index)))

(defun %set-context-register (context index new)
(declare (type (alien (* os-context-t)) context))
(setf (deref (context-register-addr context index))
      new))
;;; This is like CONTEXT-REGISTER, but returns the value of a float
;;; register. FORMAT is the type of float to return.

;;; FIXME: Whether COERCE actually knows how to make a float out of a
;;; long is another question. This stuff still needs testing.
#+nil
(define-alien-routine ("os_context_fpregister_addr" context-float-register-addr)
  (* long)
  (context (* os-context-t))
  (index int))
#+nil
(defun context-float-register (context index format)
  (declare (type (alien (* os-context-t)) context))
  (coerce (deref (context-float-register-addr context index)) format))
#+nil
(defun %set-context-float-register (context index format new)
  (declare (type (alien (* os-context-t)) context))
  (setf (deref (context-float-register-addr context index))
        (coerce new format)))

;;; Given a signal context, return the floating point modes word in
;;; the same format as returned by FLOATING-POINT-MODES.
(define-alien-routine ("os_context_fp_control" context-floating-point-modes)
    (sb!alien:unsigned 32)
  (context (* os-context-t)))


;;;; INTERNAL-ERROR-ARGS.

;;; GIVEN a (POSIX) signal context, extract the internal error
;;; arguments from the instruction stream.  This is e.g.

;;; INTERNAL-ERROR-ARGS -- interface.
;;;
;;; Given the sigcontext, extract the internal error arguments from the
;;; instruction stream.
;;; 
(defun internal-error-args (context)
  (declare (type (alien (* os-context-t)) context))
  (let* ((pc (context-pc context))
	 (bad-inst (sap-ref-32 pc 0))
	 (op (ldb (byte 16 16) bad-inst)))
    (declare (type system-area-pointer pc))
    (cond ((= op (logior (ash 3 10) (ash 6 5)))
	   (args-for-unimp-inst context))
	  ((and (= (ldb (byte 6 10) op) 3)
		(= (ldb (byte 5 5) op) 24))
	   (let* ((regnum (ldb (byte 5 0) op))
		  (prev (sap-ref-32 (int-sap (- (sap-int pc) 4)) 0)))
	     (if (and (= (ldb (byte 6 26) prev) 3)
		      (= (ldb (byte 5 21) prev) 0))
		 (values (ldb (byte 16 0) prev)
			 (list (sb!c::make-sc-offset sb!vm:any-reg-sc-number
                                                     (ldb (byte 5 16) prev))))
		 (values #.(sb!kernel:error-number-or-lose
			    'sb!kernel:invalid-arg-count-error)
                         (list (sb!c::make-sc-offset sb!vm:any-reg-sc-number regnum))))))
          
	  (t
	   (values #.(error-number-or-lose 'unknown-error) nil)))))

(defun args-for-unimp-inst (context)
  (declare (type (alien (* os-context-t)) context))
  (let* ((pc (context-pc context))
	 (length (sap-ref-8 pc 4))
	 (vector (make-array length :element-type '(unsigned-byte 8))))
    (declare (type system-area-pointer pc)
	     (type (unsigned-byte 8) length)
	     (type (simple-array (unsigned-byte 8) (*)) vector))
    (copy-from-system-area pc (* sb!vm:n-byte-bits 5)
			   vector (* sb!vm:n-word-bits
				     sb!vm:vector-data-offset)
			   (* length sb!vm:n-byte-bits))
    (let* ((index 0)
	   (error-number (sb!c::read-var-integer vector index)))
      (collect ((sc-offsets))
	       (loop
		(when (>= index length)
		  (return))
		(sc-offsets (sb!c::read-var-integer vector index)))
	       (values error-number (sc-offsets))))))