forked from dmitryvk/sbcl-win32-threads
-
Notifications
You must be signed in to change notification settings - Fork 4
/
early-vm.lisp
34 lines (30 loc) · 1.28 KB
/
early-vm.lisp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
;;;; 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")
;;; the number of bits at the low end of a pointer used for type
;;; information
(def!constant n-lowtag-bits 4)
;;; 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 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)))
(def!constant sb!xc:most-positive-fixnum
(1- (ash 1 (- n-word-bits n-lowtag-bits)))
#!+sb-doc
"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
"the fixnum closest in value to negative infinity")