X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Flate-extensions.lisp;h=3c992d0759769597e43d883eb6ede6e3585841e8;hb=5745b5a5b2e3b967bf3876b4306f31b3c78495fa;hp=e2950d6265868d2790f65c6bb600af148e1b868d;hpb=5a9a81ca693a7b82d810cbe725818cd96244099e;p=sbcl.git

diff --git a/src/code/late-extensions.lisp b/src/code/late-extensions.lisp
index e2950d6..3c992d0 100644
--- a/src/code/late-extensions.lisp
+++ b/src/code/late-extensions.lisp
@@ -167,25 +167,9 @@ EXPERIMENTAL: Interface subject to change."
   (def %compare-and-swap-symbol-value (symbol) symbol-value)
   (def %compare-and-swap-svref (vector index) svref))
 
-(defmacro atomic-incf (place &optional (diff 1))
-  #!+sb-doc
-  "Atomically increments PLACE by DIFF, and returns the value of PLACE before
-the increment.
-
-The incrementation is done using word-size modular arithmetic: on 32 bit
-platforms ATOMIC-INCF of #xFFFFFFFF by one results in #x0 being stored in
-PLACE.
-
-PLACE must be an accessor form whose CAR is the name of a DEFSTRUCT accessor
-whose declared type is (UNSIGNED-BYTE 32) on 32 bit platforms,
-and (UNSIGNED-BYTE 64) on 64 bit platforms.
-
-DIFF defaults to 1, and must be a (SIGNED-BYTE 32) on 32 bit platforms,
-and (SIGNED-BYTE 64) on 64 bit platforms.
-
-EXPERIMENTAL: Interface subject to change."
+(defun expand-atomic-frob (name place diff)
   (flet ((invalid-place ()
-           (error "Invalid first argument to ATOMIC-INCF: ~S" place)))
+           (error "Invalid first argument to ~S: ~S" name place)))
     (unless (consp place)
       (invalid-place))
     (destructuring-bind (op &rest args) place
@@ -200,27 +184,75 @@ EXPERIMENTAL: Interface subject to change."
               (declare (ignorable structure index))
               (unless (and (eq 'sb!vm:word (dsd-raw-type slotd))
                            (type= (specifier-type type) (specifier-type 'sb!vm:word)))
-                (error "ATOMIC-INCF requires a slot of type (UNSIGNED-BYTE ~S), not ~S: ~S"
-                       sb!vm:n-word-bits type place))
+                (error "~S requires a slot of type (UNSIGNED-BYTE ~S), not ~S: ~S"
+                       name sb!vm:n-word-bits type place))
               (when (dsd-read-only slotd)
-                (error "Cannot use ATOMIC-INCF with structure accessor for a read-only slot: ~S"
-                       place))
+                (error "Cannot use ~S with structure accessor for a read-only slot: ~S"
+                       name place))
               #!+(or x86 x86-64)
               `(truly-the sb!vm:word
-                          (%raw-instance-atomic-incf/word (the ,structure ,@args)
-                                                          ,index
-                                                          (the sb!vm:signed-word ,diff)))
+                          (%raw-instance-atomic-incf/word
+                           (the ,structure ,@args) ,index
+                           (logand #.(1- (ash 1 sb!vm:n-word-bits))
+                                   ,(ecase name
+                                           (atomic-incf
+                                            `(the sb!vm:signed-word ,diff))
+                                           (atomic-decf
+                                            `(- (the sb!vm:signed-word ,diff)))))))
               ;; No threads outside x86 and x86-64 for now, so this is easy...
               #!-(or x86 x86-64)
               (with-unique-names (structure old)
                 `(sb!sys:without-interrupts
                    (let* ((,structure ,@args)
                           (,old (,op ,structure)))
-                     (setf (,op ,structure) (logand #.(1- (ash 1 sb!vm:n-word-bits))
-                                                    (+ ,old (the sb!vm:signed-word ,diff))))
+                     (setf (,op ,structure)
+                           (logand #.(1- (ash 1 sb!vm:n-word-bits))
+                                   ,(ecase name
+                                           (atomic-incf
+                                            `(+ ,old (the sb!vm:signed-word ,diff)))
+                                           (atomic-decf
+                                            `(- ,old (the sb!vm:signed-word ,diff))))))
                      ,old))))
             (invalid-place))))))
 
+(defmacro atomic-incf (place &optional (diff 1))
+  #!+sb-doc
+  "Atomically increments PLACE by DIFF, and returns the value of PLACE before
+the increment.
+
+The incrementation is done using word-size modular arithmetic: on 32 bit
+platforms ATOMIC-INCF of #xFFFFFFFF by one results in #x0 being stored in
+PLACE.
+
+PLACE must be an accessor form whose CAR is the name of a DEFSTRUCT accessor
+whose declared type is (UNSIGNED-BYTE 32) on 32 bit platforms,
+and (UNSIGNED-BYTE 64) on 64 bit platforms.
+
+DIFF defaults to 1, and must be a (SIGNED-BYTE 32) on 32 bit platforms,
+and (SIGNED-BYTE 64) on 64 bit platforms.
+
+EXPERIMENTAL: Interface subject to change."
+  (expand-atomic-frob 'atomic-incf place diff))
+
+(defmacro atomic-decf (place &optional (diff 1))
+  #!+sb-doc
+  "Atomically decrements PLACE by DIFF, and returns the value of PLACE before
+the increment.
+
+The decrementation is done using word-size modular arithmetic: on 32 bit
+platforms ATOMIC-DECF of #x0 by one results in #xFFFFFFFF being stored in
+PLACE.
+
+PLACE must be an accessor form whose CAR is the name of a DEFSTRUCT accessor
+whose declared type is (UNSIGNED-BYTE 32) on 32 bit platforms,
+and (UNSIGNED-BYTE 64) on 64 bit platforms.
+
+DIFF defaults to 1, and must be a (SIGNED-BYTE 32) on 32 bit platforms,
+and (SIGNED-BYTE 64) on 64 bit platforms.
+
+EXPERIMENTAL: Interface subject to change."
+  (expand-atomic-frob 'atomic-decf place diff))
+
 (defun call-hooks (kind hooks &key (on-error :error))
   (dolist (hook hooks)
     (handler-case