#| -*-Scheme-*-

$Id: assmd.scm,v 4.13 2007/01/05 21:19:22 cph Exp $

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

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it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
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WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
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USA.

|#

;;;; Assembler Machine Dependencies.  DEC Vax version

(declare (usual-integrations))

(let-syntax ((ucode-type
	      (sc-macro-transformer
	       (lambda (form environment)
		 environment
		 (apply microcode-type (cdr form))))))

(define-integrable maximum-padding-length
  ;; Instructions can be any number of bytes long.
  ;; Thus the maximum padding is 3 bytes.
  24)

(define-integrable padding-string
  ;; Pad with HALT instructions
  (unsigned-integer->bit-string 8 #x00))

(define-integrable block-offset-width
  ;; Block offsets are encoded words
  16)

(define maximum-block-offset
  (- (expt 2 (-1+ block-offset-width)) 1))

(define-integrable (block-offset->bit-string offset start?)
  (unsigned-integer->bit-string block-offset-width
				(+ (* 2 offset)
				   (if start? 0 1))))


(define-integrable nmv-type-string
  (unsigned-integer->bit-string scheme-type-width
				(ucode-type manifest-nm-vector)))

(define (make-nmv-header n)
  (bit-string-append (unsigned-integer->bit-string scheme-datum-width n)
		     nmv-type-string))

;;; Machine dependent instruction order

(define (instruction-insert! bits block position receiver)
  (let ((l (bit-string-length bits)))
    (bit-substring-move-right! bits 0 l block position)
    (receiver (+ position l))))

(define-integrable (instruction-initial-position block)
  block					; ignored
  0)

(define-integrable instruction-append bit-string-append)

;;; end let-syntax
)