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
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
(define (make-d-vector type len key)
(make-stob type (cells->bytes len) key))
(define make-b-vector make-stob)
(define (address-after-header stob)
(assert (stob? stob))
(stob-descriptor->address stob))
(define (address-at-header stob)
(addr- (address-after-header stob) (cells->a-units 1)))
(define (stob-length-in-bytes stob)
(header-length-in-bytes (stob-header stob)))
(define (address-after-stob stob)
(addr+ (address-after-header stob)
(bytes->a-units (stob-length-in-bytes stob))))
; Accessing memory via stob descriptors
(define (stob-ref stob index)
(fetch (addr+ (address-after-header stob) (cells->a-units index))))
(define (stob-set! stob index value)
(store! (addr+ (address-after-header stob) (cells->a-units index))
value))
(define (stob-header stob)
(stob-ref stob -1))
(define (stob-header-set! stob header)
(stob-set! stob -1 header))
(define (stob-type obj)
(header-type (stob-header obj)))
(define (stob-of-type? obj type)
(and (stob? obj)
(= (stob-type obj) type)))
; Immutability
(define (immutable? thing)
(or (not (stob? thing))
(immutable-header? (stob-header thing))))
(define (make-immutable! thing)
(if (not (immutable? thing))
(stob-header-set! thing (make-header-immutable (stob-header thing)))))
; D-vectors (vectors of descriptors)
(define (d-vector? obj)
(and (stob? obj)
(< (header-type (stob-header obj)) least-b-vector-type)))
; The type in these routines is used only for internal error checking.
(define (d-vector-length x)
(assert (d-vector? x))
(header-length-in-cells (stob-header x)))
(define (d-vector-ref x index)
(assert (valid-index? index (d-vector-length x)))
(stob-ref x index))
(define (d-vector-set! x index val)
(assert (valid-index? index (d-vector-length x)))
(stob-set! x index val))
; B-vector = vector of bytes.
(define (b-vector? obj)
(and (stob? obj)
(>= (header-type (stob-header obj))
least-b-vector-type)))
(define (b-vector-length x)
(assert (b-vector? x))
(header-length-in-bytes (stob-header x)))
(define (b-vector-ref b-vector index)
(assert (valid-index? index (b-vector-length b-vector)))
(fetch-byte (addr+ (address-after-header b-vector) index)))
(define (b-vector-set! b-vector index value)
(assert (valid-index? index (b-vector-length b-vector)))
(store-byte! (addr+ (address-after-header b-vector) index) value))
; Various utilities
(define (copy-stob old-stob key)
(assert (stob? old-stob))
(let ((new (make-stob (enum stob code-vector)
(header-length-in-bytes (stob-header old-stob))
key)))
(stob-header-set! new (stob-header old-stob))
(copy-cells! (address-after-header old-stob)
(address-after-header new)
(bytes->cells (stob-length-in-bytes old-stob)))
new))
(define (copy-cells! from to count)
(let ((end (addr+ from (cells->a-units count))))
(do ((from from (addr1+ from))
(to to (addr1+ to)))
((>= from end))
(store! to (fetch from)))))
(define (stob-equal? stob1 stob2) ;CMPC3 loop or "strncmp"
(let ((z1 (stob-header stob1))
(z2 (stob-header stob2)))
(and (= (make-header-immutable z1)
(make-header-immutable z2))
(let ((z (header-length-in-cells z1)))
(let loop ((i 0))
(cond ((>= i z) #t)
((= (stob-ref stob1 i)
(stob-ref stob2 i))
(loop (+ i 1)))
(else #f)))))))
(define (valid-index? index len)
(and (>= index 0) (< index len)))
|
