#| -*-Scheme-*-

$Id: instr1.scm,v 1.8 2003/02/14 18:28:07 cph Exp $

Copyright (c) 1987-1999, 2001, 2002 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme is free software; you can redistribute it and/or modify
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
your option) any later version.

MIT/GNU Scheme is distributed in the hope that it will be useful, but
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
along with MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

|#

;;;; HP Spectrum instruction utilities
;;; Originally from Walt Hill, who did the hard part.
;;; package: (compiler lap-syntaxer)

(declare (usual-integrations))

(define-transformer complx
  (lambda (completer)
    (vector (encode-S/SM completer)
	    (cc-val completer)
	    (m-val completer))))

(define-transformer compls
  (lambda (completer)
    (vector (encode-MB completer)
	    (cc-val completer)
	    (m-val completer))))

(define-transformer compledb
  (lambda (completer)
    (cons (encode-n completer)
	  (extract-deposit-condition completer))))

(define-transformer compled
  (lambda (completer)
    (extract-deposit-condition completer)))

(define-transformer complalb
  (lambda (completer)
    (cons (encode-n completer)
	  (arith-log-condition completer))))

(define-transformer complaltfb
  (lambda (completer)
    (list (encode-n completer)
	  (let ((val (arith-log-condition completer)))
	    (if (not (zero? (cadr val)))
		(error "complaltfb: Bad completer" completer)
		(car val))))))

(define-transformer complal
  (lambda (completer)
    (arith-log-condition completer)))

(define-transformer complaltf
  (lambda (completer)
    (let ((val (arith-log-condition completer)))
      (if (not (zero? (cadr val)))
	  (error "complaltf: Bad completer" completer)
	  val))))

(define-transformer fpformat
  (lambda (completer)
    (encode-fpformat completer)))

(define-transformer fpcond
  (lambda (completer)
    (encode-fpcond completer)))

(define-transformer sr3
  (lambda (value)
    (let ((place (assq value '((0 . 0) (1 . 2) (2 . 4) (3 . 6)
			       (4 . 1) (5 . 3) (6 . 5) (7 . 7)))))
      (if place
	  (cdr place)
	  (error "sr3: Invalid space register descriptor" value)))))

;;;; Utilities

(define-integrable (branch-extend-pco disp nullify?)
  (if (and (= nullify? 1)
	   (negative? disp))
      4
      0))

(define-integrable (branch-extend-nullify disp nullify?)
  (if (and (= nullify? 1)
	  (not (negative? disp)))
      1
      0))

(define-integrable (branch-extend-disp disp)
  (- disp 4))

(define-integrable (branch-extend-edcc cc)
  (remainder (+ cc 4) 8))

(define-integrable (encode-N completers)
  (if (memq 'N completers)
      1
      0))

(define-integrable (encode-S/SM completers)
  (if (or (memq 'S completers) (memq 'SM completers))
      1
      0))

(define-integrable (encode-MB completers)
  (if (memq 'MB completers)
      1
      0))

(define-integrable (m-val compl-list)
  (if (or (memq 'M compl-list)
	  (memq 'SM compl-list)
	  (memq 'MA compl-list)
	  (memq 'MB compl-list))
      1
      0))

(define-integrable (cc-val compl-list)
  (cond ((memq 'P compl-list) 3)
	((memq 'Q compl-list) 2)
	((memq 'C compl-list) 1)
	(else 0)))

(define (extract-deposit-condition compl)
  (cond ((or (null? compl) (memq 'NV compl)) 0)
	((or (memq 'EQ compl) (memq '= compl)) 1)
	((or (memq 'LT compl) (memq '< compl)) 2)
	((memq 'OD compl) 3)
	((memq 'TR compl) 4)
	((or (memq 'LTGT compl) (memq '<> compl)) 5)
	((or (memq 'GTEQ compl) (memq '>= compl)) 6)
	((memq 'EV compl) 7)
	(else
	 ;; This should really error out, but it's hard to
	 ;; arrange given that the compl includes other
	 ;; fields.
	 0)))

(define-integrable (encode-fpformat compl)
  (case compl
    ((DBL) 1)
    ((SGL) 0)
    ((QUAD) 3)
    (else
     (error "Missing Floating Point Format" compl))))

(define-integrable (encode-fpcond fpcond)
  (let ((place (assq fpcond float-condition-table)))
    (if place
	(cadr place)
	(error "encode-fpcond: Unknown condition" fpcond))))

(define float-condition-table
  '((false?	0)
    (false	1)
    (?		2)
    (!<=>	3)
    (=		4)
    (=T		5)
    (?=		6)
    (!<>	7)
    (!?>=	8)
    (<		9)
    (?<		10)
    (!>=	11)
    (!?>	12)
    (<=		13)
    (?<=	14)
    (!>		15)
    (!?<=	16)
    (>		17)
    (?>		18)
    (!<=	19)
    (!?<	20)
    (>=		21)
    (?>=	22)
    (!<		23)
    (!?=	24)
    (<>		25)
    (!=		26)
    (!=T	27)
    (!?		28)
    (<=>	29)
    (true?	30)
    (true	31)))
    
(define (arith-log-condition compl-list)
  ;; Returns (c f)
  (let loop ((compl-list compl-list))
    (if (null? compl-list)
	'(0 0)
	(let ((val (assq (car compl-list) arith-log-condition-table)))
	  (if val
	      (cadr val)
	      (loop (cdr compl-list)))))))

(define arith-log-condition-table
  '((NV      (0 0))
    (EQ      (1 0))
    (=       (1 0))
    (LT      (2 0))
    (<       (2 0))
    (SBZ     (2 0))
    (LTEQ    (3 0))
    (<=      (3 0))
    (SHZ     (3 0))
    (LTLT    (4 0))
    (<<      (4 0))
    (NUV     (4 0))
    (SDC     (4 0))
    (LTLTEQ  (5 0))
    (<<=     (5 0))
    (ZNV     (5 0))
    (SV      (6 0))
    (SBC     (6 0))
    (OD      (7 0))
    (SHC     (7 0))
    (TR      (0 1))
    (LTGT    (1 1))
    (<>      (1 1))
    (GTEQ    (2 1))
    (>=      (2 1))
    (NBZ     (2 1))
    (GT      (3 1))
    (>       (3 1))
    (NHZ     (3 1))
    (GTGTEQ  (4 1))
    (>>=     (4 1))
    (UV      (4 1))
    (NDC     (4 1))
    (GTGT    (5 1))
    (>>      (5 1))
    (VNZ     (5 1))
    (NSV     (6 1))
    (NBC     (6 1))
    (EV      (7 1))
    (NHC     (7 1))))

(define-integrable (tf-adjust opcode condition)
  (+ opcode (* 2 (cadr condition))))

(define (tf-adjust-inverted opcode condition)
  (+ opcode (* 2 (- 1 (cadr condition)))))

(define (make-operator name handler)
  (lambda (value)
    (if (exact-integer? value)
	(handler value)
	`(,name ,value))))	

(let-syntax ((define-operator
	       (sc-macro-transformer
		(lambda (form environment)
		  `(DEFINE ,(cadr form)
		     (MAKE-operator ',(cadr form)
				    ,(close-syntax (caddr form)
						   environment)))))))

  (define-operator LEFT
    (lambda (number)
      (bit-string->signed-integer
       (bit-substring (signed-integer->bit-string 32 number) 11 32))))

  (define-operator RIGHT
    (lambda (number)
      (bit-string->unsigned-integer
       (bit-substring (signed-integer->bit-string 32 number) 0 11)))))