;;;; the Alpha VM definition of character operations

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!VM")

;;;; moves and coercions

;;; Move a tagged char to an untagged representation.
(define-vop (move-to-base-char)
  (:args (x :scs (any-reg descriptor-reg)))
  (:results (y :scs (base-char-reg)))
  (:generator 1
    (inst srl x sb!vm:n-widetag-bits y)))
;;;
(define-move-vop move-to-base-char :move
  (any-reg descriptor-reg) (base-char-reg))

;;; Move an untagged char to a tagged representation.
(define-vop (move-from-base-char)
  (:args (x :scs (base-char-reg)))
  (:results (y :scs (any-reg descriptor-reg)))
  (:generator 1
    (inst sll x sb!vm:n-widetag-bits y)
    (inst bis y sb!vm:base-char-widetag y)))
;;;
(define-move-vop move-from-base-char :move
  (base-char-reg) (any-reg descriptor-reg))

;;; Move untagged base-char values.
(define-vop (base-char-move)
  (:args (x :target y
	    :scs (base-char-reg)
	    :load-if (not (location= x y))))
  (:results (y :scs (base-char-reg)
	       :load-if (not (location= x y))))
  (:effects)
  (:affected)
  (:generator 0
    (move x y)))
;;;
(define-move-vop base-char-move :move
  (base-char-reg) (base-char-reg))

;;; Move untagged base-char arguments/return-values.
(define-vop (move-base-char-arg)
  (:args (x :target y
	    :scs (base-char-reg))
	 (fp :scs (any-reg)
	     :load-if (not (sc-is y base-char-reg))))
  (:results (y))
  (:generator 0
    (sc-case y
      (base-char-reg
       (move x y))
      (base-char-stack
       (storew x fp (tn-offset y))))))
;;;
(define-move-vop move-base-char-arg :move-arg
  (any-reg base-char-reg) (base-char-reg))


;;; Use standard MOVE-ARG + coercion to move an untagged base-char
;;; to a descriptor passing location.
;;;
(define-move-vop move-arg :move-arg
  (base-char-reg) (any-reg descriptor-reg))

;;;; other operations

(define-vop (char-code)
  (:translate char-code)
  (:policy :fast-safe)
  (:args (ch :scs (base-char-reg) :target res))
  (:arg-types base-char)
  (:results (res :scs (any-reg)))
  (:result-types positive-fixnum)
  (:generator 1
    (inst sll ch 2 res)))

(define-vop (code-char)
  (:translate code-char)
  (:policy :fast-safe)
  (:args (code :scs (any-reg) :target res))
  (:arg-types positive-fixnum)
  (:results (res :scs (base-char-reg)))
  (:result-types base-char)
  (:generator 1
    (inst srl code 2 res)))

;;;; comparison of BASE-CHARs

(define-vop (base-char-compare)
  (:args (x :scs (base-char-reg))
	 (y :scs (base-char-reg)))
  (:arg-types base-char base-char)
  (:temporary (:scs (non-descriptor-reg)) temp)
  (:conditional)
  (:info target not-p)
  (:policy :fast-safe)
  (:note "inline comparison")
  (:variant-vars cond)
  (:generator 3
    (ecase cond
      (:eq (inst cmpeq x y temp))
      (:lt (inst cmplt x y temp))
      (:gt (inst cmplt y x temp)))
    (if not-p
	(inst beq temp target)
	(inst bne temp target))))

(define-vop (fast-char=/base-char base-char-compare)
  (:translate char=)
  (:variant :eq))

(define-vop (fast-char</base-char base-char-compare)
  (:translate char<)
  (:variant :lt))

(define-vop (fast-char>/base-char base-char-compare)
  (:translate char>)
  (:variant :gt))