X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fgeneric%2Fearly-vm.lisp;h=57c2d9d55b34388add8551a170cfe66885b2b1fc;hb=672b2f6cb751566526c7f3bb3de6b7d8424760e2;hp=c5f8a94c6dafca8484cb65275bdc519573a91dbf;hpb=95a6db7329b91dd90d165dd4057b9b5098d34aa2;p=sbcl.git

diff --git a/src/compiler/generic/early-vm.lisp b/src/compiler/generic/early-vm.lisp
index c5f8a94..57c2d9d 100644
--- a/src/compiler/generic/early-vm.lisp
+++ b/src/compiler/generic/early-vm.lisp
@@ -9,30 +9,48 @@
 
 (in-package "SB!VM")
 
-(defconstant lowtag-bits 3
-  #!+sb-doc
-  "Number of bits at the low end of a pointer used for type information.")
+;;; the number of bits at the low end of a pointer used for type
+;;; information
+(def!constant n-lowtag-bits
+  (integer-length (1- (/ (* 2 n-word-bits) n-byte-bits))))
+;;; a mask to extract the low tag bits from a pointer
+(def!constant lowtag-mask (1- (ash 1 n-lowtag-bits)))
+;;; the exclusive upper bound on the value of the low tag bits from a
+;;; pointer
+(def!constant lowtag-limit (ash 1 n-lowtag-bits))
+;;; the number of tag bits used for a fixnum
+(def!constant n-fixnum-tag-bits (1- n-lowtag-bits))
+;;; the fixnum tag mask
+(def!constant fixnum-tag-mask (1- (ash 1 n-fixnum-tag-bits)))
+;;; the bit width of positive fixnums
+(def!constant n-positive-fixnum-bits (- n-word-bits n-fixnum-tag-bits 1))
 
-(defconstant lowtag-mask (1- (ash 1 lowtag-bits))
-  #!+sb-doc
-  "Mask to extract the low tag bits from a pointer.")
+;;; the number of bits to shift between word addresses and byte addresses
+(def!constant word-shift (1- (integer-length (/ n-word-bits n-byte-bits))))
 
-(defconstant lowtag-limit (ash 1 lowtag-bits)
-  #!+sb-doc
-  "Exclusive upper bound on the value of the low tag bits from a pointer.")
+;;; the number of bytes in a word
+(def!constant n-word-bytes (/ n-word-bits n-byte-bits))
 
-(defconstant type-bits 8
-  #!+sb-doc
-  "Number of bits used in the header word of a data block to store the type.")
+;;; the number of bits used in the header word of a data block to store
+;;; the type
+(def!constant n-widetag-bits 8)
+;;; a mask to extract the type from a data block header word
+(def!constant widetag-mask (1- (ash 1 n-widetag-bits)))
 
-(defconstant type-mask (1- (ash 1 type-bits))
+(def!constant sb!xc:most-positive-fixnum
+    (1- (ash 1 (- n-word-bits n-lowtag-bits)))
   #!+sb-doc
-  "Mask to extract the type from a header word.")
-
-;;; FIXME: Couldn't/shouldn't these be DEFCONSTANT instead of DEFPARAMETER?
-(defparameter *target-most-positive-fixnum* (1- (ash 1 29))
-  #!+sb-doc
-  "most-positive-fixnum in the target architecture.")
-(defparameter *target-most-negative-fixnum* (ash -1 29)
+  "the fixnum closest in value to positive infinity")
+(def!constant sb!xc:most-negative-fixnum
+    (ash -1 (- n-word-bits n-lowtag-bits))
   #!+sb-doc
-  "most-negative-fixnum in the target architecture.")
+  "the fixnum closest in value to negative infinity")
+
+(def!constant most-positive-exactly-single-float-fixnum
+  (min #xffffff most-positive-fixnum))
+(def!constant most-negative-exactly-single-float-fixnum
+  (max #x-ffffff most-negative-fixnum))
+(def!constant most-positive-exactly-double-float-fixnum
+  (min #x1fffffffffffff most-positive-fixnum))
+(def!constant most-negative-exactly-double-float-fixnum
+  (max #x-1fffffffffffff most-negative-fixnum))