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
|
local lg = {}
-- (de)serialize
lg.serialize = function(t)
local function _op(t)
if t == nil then
return " "
elseif t.type == "io" then
return t.port
else -- t.type == "reg"
return tostring(t.n)
end
end
local function _action(s)
if s == nil then
return " "
end
local mapping = {
["and"] = "&",
["or"] = "|",
["not"] = "~",
["xor"] = "^",
["nand"] = "?", --dunno
["buf"] = "_",
["xnor"] = "=",
}
return mapping[s]
end
local s = ""
for i = 1, 14 do
local cur = t[i]
if next(cur) ~= nil then
s = s .. _op(cur.op1) .. _action(cur.action) .. _op(cur.op2) .. _op(cur.dst)
end
s = s .. "/"
end
return s
end
lg.deserialize = function(s)
local function _op(c)
if c == "A" or c == "B" or c == "C" or c == "D" then
return {type = "io", port = c}
elseif c == " " then
return nil
else
return {type = "reg", n = tonumber(c)}
end
end
local function _action(c)
local mapping = {
["&"] = "and",
["|"] = "or",
["~"] = "not",
["^"] = "xor",
["?"] = "nand",
["_"] = "buf",
["="] = "xnor",
[" "] = nil,
}
return mapping[c]
end
local ret = {}
for part in s:gmatch("(.-)/") do
local parsed
if part == "" then
parsed = {}
else
parsed = {
action = _action( part:sub(2,2) ),
op1 = _op( part:sub(1,1) ),
op2 = _op( part:sub(3,3) ),
dst = _op( part:sub(4,4) ),
}
end
ret[#ret + 1] = parsed
end
-- More than 14 instructions (write to all 10 regs + 4 outputs)
-- will not pass the write-once requirement of the validator
assert(#ret == 14)
return ret
end
-- validation
lg.validate_single = function(t, i)
local function is_reg_written_to(t, n, max)
for i = 1, max-1 do
if next(t[i]) ~= nil
and t[i].dst and t[i].dst.type == "reg"
and t[i].dst.n == n then
return true
end
end
return false
end
local function compare_op(t1, t2, allow_same_io)
if t1 == nil or t2 == nil then
return false
elseif t1.type ~= t2.type then
return false
end
if t1.type == "reg" and t1.n == t2.n then
return true
elseif t1.type == "io" and t1.port == t2.port then
return not allow_same_io
end
return false
end
local elem = t[i]
-- check for completeness
if elem.action == nil then
return {i = i, msg = "Gate type required"}
elseif elem.action == "not" or elem.action == "buf" then
if elem.op1 ~= nil or elem.op2 == nil or elem.dst == nil then
return {i = i, msg = "Second operand (only) and destination required"}
end
else
if elem.op1 == nil or elem.op2 == nil or elem.dst == nil then
return {i = i, msg = "Operands and destination required"}
end
end
-- check whether operands/destination are identical
if compare_op(elem.op1, elem.op2) then
return {i = i, msg = "Operands cannot be identical"}
end
if compare_op(elem.op1, elem.dst, true) or compare_op(elem.op2, elem.dst, true) then
return {i = i, msg = "Destination and operands must be different"}
end
-- check whether operands point to defined registers
if elem.op1 ~= nil and elem.op1.type == "reg"
and not is_reg_written_to(t, elem.op1.n, i) then
return {i = i, msg = "First operand is undefined register"}
end
if elem.op2.type == "reg" and not is_reg_written_to(t, elem.op2.n, i) then
return {i = i, msg = "Second operand is undefined register"}
end
-- check whether destination points to undefined register
if elem.dst.type == "reg" and is_reg_written_to(t, elem.dst.n, i) then
return {i = i, msg = "Destination is already used register"}
end
return nil
end
lg.validate = function(t)
for i = 1, 14 do
if next(t[i]) ~= nil then
local r = lg.validate_single(t, i)
if r ~= nil then
return r
end
end
end
return nil
end
-- interpreter
lg.interpret = function(t, a, b, c, d)
local function _action(s, v1, v2)
if s == "and" then
return v1 and v2
elseif s == "or" then
return v1 or v2
elseif s == "not" then
return not v2
elseif s == "xor" then
return v1 ~= v2
elseif s == "nand" then
return not (v1 and v2)
elseif s == "buf" then
return v2
else -- s == "xnor"
return v1 == v2
end
end
local function _op(t, regs, io_in)
if t.type == "reg" then
return regs[t.n]
else -- t.type == "io"
return io_in[t.port]
end
end
local io_in = {A=a, B=b, C=c, D=d}
local regs = {}
local io_out = {}
for i = 1, 14 do
local cur = t[i]
if next(cur) ~= nil then
local v1, v2
if cur.op1 ~= nil then
v1 = _op(cur.op1, regs, io_in)
end
v2 = _op(cur.op2, regs, io_in)
local result = _action(cur.action, v1, v2)
if cur.dst.type == "reg" then
regs[cur.dst.n] = result
else -- cur.dst.type == "io"
io_out[cur.dst.port] = result
end
end
end
return io_out.A, io_out.B, io_out.C, io_out.D
end
return lg
|
