1 ;;;; type-based constants
3 ;;;; This software is part of the SBCL system. See the README file for
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
14 ;;; FIXME: It's clever using :SUFFIX -TYPE for these things, but it's
15 ;;; a pain for people just learning to find their way around the code
16 ;;; who want to use lexical search to figure out where things like
17 ;;; EVEN-FIXNUM-LOWTAG are defined. Remove the :SUFFIXes and just expand
18 ;;; out the full names. Or even define them in DEF EVEN-FIXNUM-LOWTAG
19 ;;; style so searches like 'def.*even-fixnum-lowtag' can find them.
21 ;;; Tags for the main low-level types are stored in the low three
22 ;;; bits to identify the type of a machine word. Certain constraints
24 ;;; * EVEN-FIXNUM-LOWTAG and ODD-FIXNUM-LOWTAG must be 0 and 4: code
25 ;;; which shifts left two places to convert raw integers to tagged
26 ;;; fixnums is ubiquitous.
27 ;;; * LIST-POINTER-LOWTAG + 4 = OTHER-POINTER-LOWTAG: NIL is both a
28 ;;; cons and a symbol (at the same address) and depends on this.
29 ;;; See the definition of SYMBOL in objdef.lisp
30 ;;; * OTHER-POINTER-LOWTAG > 4: Some code in the SPARC backend,
31 ;;; which uses bit 2 of the ALLOC register to indicate that
32 ;;; PSEUDO-ATOMIC is on, doesn't strip the low bits of reg_ALLOC
33 ;;; before ORing in OTHER-POINTER-LOWTAG within a PSEUDO-ATOMIC
35 ;;; (These are just the ones we know about as of sbcl-0.7.1.22. There
36 ;;; might easily be more, since these values have stayed highly
37 ;;; constrained for more than a decade, an inviting target for
38 ;;; inventive abstraction-phobic maintainers.:-)
39 (eval-when (:compile-toplevel :load-toplevel :execute)
40 ;; The EVAL-WHEN is necessary (at least for Lispworks), because the
41 ;; second DEFENUM uses the value of OTHER-IMMEDIATE-0-LOWTAG, which is
42 ;; defined in the first DEFENUM. -- AL 20000216
43 (defenum (:suffix -lowtag)
45 ;; Note: CMU CL, and SBCL < 0.pre7.39, had FUN-POINTER-LOWTAG
46 ;; here. We swapped FUN-POINTER-LOWTAG and
47 ;; INSTANCE-POINTER-LOWTAG in sbcl-0.pre7.39 in order to help with a
48 ;; low-level pun in the function call sequence on the PPC port.
49 ;; For more information, see the PPC port code. -- WHN 2001-10-03
58 ;;; the heap types, stored in 8 bits of the header of an object on the
59 ;;; heap, to identify the type of the heap object (which'll be at
60 ;;; least two machine words, often more)
62 ;;; Note: the order specified here is not critical for correctness,
63 ;;; but (FIXME) with %TEST-HEADERS as currently defined, BIGNUM must
64 ;;; be first, and COMPLEX-ARRAY must be last.
66 ;;; However, for efficiency, we prefer contiguous sets of widetags for
67 ;;; "similar" objects, so that type checking can be done with a range
68 ;;; check, rather than several individual checks.
70 ;;; * BIGNUM + RATIO (+ FIXNUM) = RATIONAL
72 ;;; * SINGLE-FLOAT + DOUBLE-FLOAT + LONG-FLOAT = FLOAT
74 ;;; * RATIONAL + FLOAT = REAL
76 ;;; * (FIXME: COMPLEX example, which needs fixing anyway -- see
77 ;;; UPGRADED-COMPLEX-PART-TYPE)
79 ;;; * SIMPLE-ARRAY-* = (SIMPLE-ARRAY * (*))
81 ;;; * SIMPLE-ARRAY-NIL + SIMPLE-BASE-STRING = SIMPLE-STRING
83 ;;; * SIMPLE-ARRAY + COMPLEX-ARRAYOID = (SATISFIES ARRAY-HEADER-P)
86 ;;; sufficient care we can cause extra combinations to appear with
87 ;;; differences in only one bit, permitting a more efficient type
88 ;;; test. As an example, if SIMPLE-BASE-STRING = 0xA6 and
89 ;;; COMPLEX-BASE-STRING = 0xE6, then the type test for BASE-STRING is
91 ;;; AND tag, ~0x40, tag
92 ;;; ANDcc tag, 0xA6, tag
95 ;;; rather than two separate tests and jumps
96 (defenum (:suffix -widetag
97 :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
98 :step (ash 1 (1- n-lowtag-bits)))
103 #!+long-float long-float
107 #!+long-float complex-long-float
112 funcallable-instance-header
132 #!-long-float unused08
133 #!-long-float unused09
135 #!+long-float simple-array-long-float
136 #!+long-float simple-array-complex-long-float
137 #!-long-float unused10
138 #!-long-float unused11
140 simple-array-unsigned-byte-2
141 simple-array-unsigned-byte-4
142 simple-array-unsigned-byte-7
143 simple-array-unsigned-byte-8
144 simple-array-unsigned-byte-15
145 simple-array-unsigned-byte-16
150 simple-array-unsigned-byte-29
151 simple-array-unsigned-byte-31
152 simple-array-unsigned-byte-32
153 simple-array-signed-byte-8
154 simple-array-signed-byte-16
155 simple-array-signed-byte-30
156 simple-array-signed-byte-32
157 simple-array-single-float
158 simple-array-double-float
159 simple-array-complex-single-float
160 simple-array-complex-double-float
169 ;;; the different vector subtypes
170 (defenum (:prefix vector- :suffix -subtype)