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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
(in-package "ACL2")
(include-book "cat-def")
(local ; ACL2 primitive
(defun natp (x)
(declare (xargs :guard t))
(and (integerp x)
(<= 0 x))))
(defund bvecp (x k)
(declare (xargs :guard (integerp k)))
(and (integerp x)
(<= 0 x)
(< x (expt 2 k))))
(defund bitn (x n)
(declare (xargs :guard (and (natp x)
(natp n))
:verify-guards nil))
(mbe :logic (bits x n n)
:exec (if (evenp (ash x (- n))) 0 1)))
(defund setbits (x w i j y)
(declare (xargs :guard (and (natp x)
(natp y)
(integerp i)
(integerp j)
(<= 0 j)
(<= j i)
(integerp w)
(< i w))
:verify-guards nil))
(mbe :logic (cat (bits x (1- w) (1+ i))
(+ -1 w (- i))
(cat (bits y (+ i (- j)) 0)
(+ 1 i (- j))
(bits x (1- j) 0)
j)
(1+ i))
:exec (cond ((int= j 0)
(cond ((int= (1+ i) w)
(bits y (+ i (- j)) 0))
(t
(cat (bits x (1- w) (1+ i))
(+ -1 w (- i))
(bits y (+ i (- j)) 0)
(1+ i)))))
((int= (1+ i) w)
(cat (bits y (+ i (- j)) 0)
(+ 1 i (- j))
(bits x (1- j) 0)
j))
(t
(cat (bits x (1- w) (1+ i))
(+ -1 w (- i))
(cat (bits y (+ i (- j)) 0)
(+ 1 i (- j))
(bits x (1- j) 0)
j)
(1+ i))))))
(local (include-book "setbits"))
(local (include-book "../arithmetic/top"))
(local (include-book "bits"))
(local (include-book "cat"))
(defund setbitn (x w n y)
(declare (xargs :guard (and (natp x)
(natp y)
(integerp n)
(<= 0 n)
(integerp w)
(< n w))
:verify-guards nil))
(setbits x w n n y))
(defthm setbitn-nonnegative-integer-type
(and (integerp (setbitn x w n y))
(<= 0 (setbitn x w n y)))
:hints (("Goal" :in-theory (enable setbitn)))
:rule-classes (:type-prescription)
)
;this rule is no better than setbits-nonnegative-integer-type and might be worse:
(in-theory (disable (:type-prescription setbitn)))
(defthm setbitn-natp
(natp (setbitn x w n y)))
;add setbitn-bvecp-simple?
(defthm setbitn-bvecp
(implies (and (<= w k)
(case-split (integerp k)))
(bvecp (setbitn x w n y) k))
:hints (("goal" :in-theory (enable setbitn))))
(defthm setbitn-rewrite
(implies (syntaxp (quotep n))
(equal (setbitn x w n y)
(setbits x w n n y)))
:hints (("Goal" :in-theory (enable setbitn))))
;gen?
(defthm bitn-setbitn
(implies (and (case-split (bvecp y 1))
(case-split (< 0 w))
(case-split (< n w))
(case-split (< k w))
(case-split (<= 0 k))
(case-split (integerp w))
(case-split (integerp n))
(<= 0 n)
(case-split (integerp k))
)
(equal (bitn (setbitn x w n y) k)
(if (equal n k)
y
(bitn x k))))
:hints (("Goal" :cases ((< n k) (= n k))
:in-theory (enable setbitn bitn bits-does-nothing)))
)
(defthm setbitn-setbitn
(implies (and (case-split (<= 0 n))
(case-split (< n w))
(case-split (integerp w))
(case-split (integerp n))
)
(equal (setbitn (setbitn x w n y) w n y2)
(setbitn x w n y2)))
:hints (("Goal"
:in-theory (enable setbits setbitn natp)))
)
(defthm setbitn-does-nothing
(implies (and (case-split (<= 0 n))
(case-split (< n w))
(case-split (integerp w))
(case-split (integerp n))
)
(equal (setbitn x w n (bitn x n))
(bits x (1- w) 0))
)
:hints (("Goal" :cases ((< (+ -1 W) (+ 1 N)))
:in-theory (enable bitn setbits setbitn natp)))
)
#|
;bad name?
(defthm setbitn-commutativity
(implies (and (< n n2);(not (equal n n2))
(case-split (<= 0 n))
(case-split (<= 0 n2))
(case-split (< n w))
(case-split (< n2 w))
(case-split (integerp w))
(case-split (integerp n))
(case-split (integerp n2))
(case-split (bvecp y 1))
(case-split (bvecp y2 1))
(case-split (bvecp x w)) ;drop!
)
(equal (setbitn (setbitn x w n y) w n2 y2)
(setbitn (setbitn x w n2 y2) w n y)
))
:rule-classes ((:rewrite :loop-stopper ((n n2 s))))
:hints (("Goal"
:in-theory (enable setbitn setbits-rewrite setbits-rewrite-when-j-is-0)))
)
(defthm setbitn-commutativity
(implies (and (< n n2);(not (equal n n2))
(case-split (<= 0 n))
(case-split (<= 0 n2))
(case-split (< n w))
(case-split (< n2 w))
(case-split (integerp w))
(case-split (integerp n))
(case-split (integerp n2))
(case-split (bvecp y 1))
(case-split (bvecp y2 1))
(case-split (bvecp x w)) ;drop!
)
(equal (setbitn (setbitn x w n y) w n2 y2)
(setbitn (setbitn x w n2 y2) w n y)
))
:rule-classes ((:rewrite :loop-stopper ((n n2 s))))
:hints (("Goal"
:in-theory (set-difference-theories
(enable setbitn setbits-rewrite setbits-rewrite-when-j-is-0
; bits-bits-1
; bits-bits-2
bits-ocat-1
bits-ocat-2
bits-ocat-3
; natp
)
'(bits-bits bits-ocat)
))
))
prove bits-setbitn?
|#
|
