X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fhash-table.lisp;h=1811acfe0d15af8ec14f2e4f5a6b8a6ddf269b2f;hb=d1e7b48b17180a417c41ed55eb382ebf6d4e7a2a;hp=d8f5e136353f06f674eb0556eb65c5f771175ed9;hpb=bc1783335d78be988465e4fc7cf9c5fdb88a3fa4;p=sbcl.git

diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp
index d8f5e13..1811acf 100644
--- a/src/code/hash-table.lisp
+++ b/src/code/hash-table.lisp
@@ -66,10 +66,22 @@
   ;; This table parallels the KV table, and can be used to store the
   ;; hash associated with the key, saving recalculation. Could be
   ;; useful for EQL, and EQUAL hash tables. This table is not needed
-  ;; for EQ hash tables, and when present the value of #x80000000
-  ;; represents EQ-based hashing on the respective key.
+  ;; for EQ hash tables, and when present the value of
+  ;; +MAGIC-HASH-VECTOR-VALUE+ represents EQ-based hashing on the
+  ;; respective key.
   (hash-vector nil :type (or null (simple-array (unsigned-byte
-                                                 #.sb!vm:n-word-bits) (*)))))
+                                                 #.sb!vm:n-word-bits) (*))))
+  ;; This lock is acquired by %PUTHASH, REMHASH, CLRHASH and GETHASH.
+  (spinlock (sb!thread::make-spinlock)))
+
+;; as explained by pmai on openprojects #lisp IRC 2002-07-30: #x80000000
+;; is bigger than any possible nonEQ hash value, and thus indicates an
+;; empty slot; and EQ hash tables don't use HASH-TABLE-HASH-VECTOR.
+;; The previous sentence was written when SBCL was 32-bit only. The value
+;; now depends on the word size. It is propagated to C in genesis because
+;; the generational garbage collector needs to know it.
+(defconstant +magic-hash-vector-value+ (ash 1 (1- sb!vm:n-word-bits)))
+
 
 (defmacro-mundanely with-hash-table-iterator ((function hash-table) &body body)
   #!+sb-doc