src/code/host-c-call.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3 ;;;;
   4 ;;;; This software is derived from the CMU CL system, which was
   5 ;;;; written at Carnegie Mellon University and released into the
   6 ;;;; public domain. The software is in the public domain and is
   7 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
   8 ;;;; files for more information.
   9
  10 (in-package "SB!ALIEN")
  11
  12 (/show0 "host-c-call.lisp 12")
  13
  14 (define-alien-type-class (c-string :include pointer :include-args (to))
  15   (external-format :default :type keyword)
  16   (element-type 'character :type (member character base-char)))
  17
  18 (define-alien-type-translator c-string
  19     (&key (external-format :default)
  20           (element-type 'character))
  21   (make-alien-c-string-type
  22    :to (parse-alien-type 'char (sb!kernel:make-null-lexenv))
  23    :element-type element-type
  24    :external-format external-format))
  25
  26 (defun c-string-external-format (type)
  27   (let ((external-format (alien-c-string-type-external-format type)))
  28     (if (eq external-format :default)
  29         (default-c-string-external-format)
  30         external-format)))
  31
  32 (define-alien-type-method (c-string :unparse) (type)
  33   (list 'c-string
  34         :external-format (alien-c-string-type-external-format type)
  35         :element-type (alien-c-string-type-element-type type)))
  36
  37 (define-alien-type-method (c-string :lisp-rep) (type)
  38   (declare (ignore type))
  39   '(or simple-string null (alien (* char)) (simple-array (unsigned-byte 8))))
  40
  41 (define-alien-type-method (c-string :deport-pin-p) (type)
  42   (declare (ignore type))
  43   t)
  44
  45 (defun c-string-needs-conversion-p (type)
  46   #+sb-xc-host
  47   (declare (ignore type))
  48   #+sb-xc-host
  49   t
  50   #-sb-xc-host
  51   (let ((external-format (sb!impl::get-external-format
  52                           ;; Can't use C-STRING-EXTERNAL-FORMAT here,
  53                           ;; since the meaning of :DEFAULT can change
  54                           ;; when *DEFAULT-C-STRING-EXTERNAL-FORMAT*
  55                           ;; changes.
  56                           (alien-c-string-type-external-format type))))
  57     (not (and external-format
  58               (or (eq (first (sb!impl::ef-names external-format)) :ascii)
  59                   ;; On non-SB-UNICODE all latin-1 codepoints will fit
  60                   ;; into a base-char, on SB-UNICODE they won't.
  61                   #!-sb-unicode
  62                   (eq (first (sb!impl::ef-names external-format)) :latin-1))))))
  63
  64 (define-alien-type-method (c-string :naturalize-gen) (type alien)
  65   `(if (zerop (sap-int ,alien))
  66        nil
  67        ;; Check whether we need to do a full external-format
  68        ;; conversion, or whether we can just do a cheap byte-by-byte
  69        ;; copy of the c-string data.
  70        ;;
  71        ;; On SB-UNICODE we can never do the cheap copy, even if the
  72        ;; external format and element-type are suitable, since
  73        ;; simple-base-strings may not contain ISO-8859-1 characters.
  74        ;; If we need to check for non-ascii data in the input, we
  75        ;; might as well go through the usual external-format machinery
  76        ;; instead of rewriting another version of it.
  77        ,(if #!+sb-unicode t
  78             #!-sb-unicode (c-string-needs-conversion-p type)
  79             `(sb!alien::c-string-to-string ,alien
  80                                            (c-string-external-format ,type)
  81                                            (alien-c-string-type-element-type
  82                                             ,type))
  83             `(%naturalize-c-string ,alien))))
  84
  85 (define-alien-type-method (c-string :deport-gen) (type value)
  86   (declare (ignore type))
  87   ;; This SAP taking is safe as DEPORT callers pin the VALUE when
  88   ;; necessary.
  89   `(etypecase ,value
  90      (null (int-sap 0))
  91      ((alien (* char)) (alien-sap ,value))
  92      (vector (vector-sap ,value))))
  93
  94 (define-alien-type-method (c-string :deport-alloc-gen) (type value)
  95   `(etypecase ,value
  96      (null nil)
  97      ((alien (* char)) ,value)
  98      (simple-base-string
  99       ,(if (c-string-needs-conversion-p type)
 100            ;; If the alien type is not ascii-compatible (+SB-UNICODE)
 101            ;; or latin-1-compatible (-SB-UNICODE), we need to do
 102            ;; external format conversion.
 103            `(string-to-c-string ,value
 104                                 (c-string-external-format ,type))
 105            ;; Otherwise we can just pass it uncopied.
 106            value))
 107      (simple-string
 108       (string-to-c-string ,value
 109                           (c-string-external-format ,type)))))
 110
 111 (/show0 "host-c-call.lisp end of file")