quick and dirty pure lua webassembly interpreter
more instructions, memory
+309
-35
+2
constants.lua
+2
constants.lua
+25
intutil.lua
+25
intutil.lua
···
1
1
local intutil = {}
2
2
3
+
function intutil.fromle16(tab, idx)
4
+
local n = tab[idx]
5
+
n = n | tab[idx+1] << 8
6
+
return n
7
+
end
8
+
9
+
function intutil.tole16(tab, idx, n)
10
+
tab[idx] = n & 0xFF
11
+
tab[idx+1] = (n >> 8) & 0xFF
12
+
end
13
+
3
14
function intutil.fromle32(tab, idx)
4
15
local n = tab[idx]
5
16
n = n | tab[idx+1] << 8
···
41
52
function intutil.signexti32(n)
42
53
if (n & 0x80000000) ~= 0 then
43
54
n = n | 0xFFFFFFFF00000000
55
+
end
56
+
return n
57
+
end
58
+
59
+
function intutil.signexti16(n)
60
+
if (n & 0x8000) ~= 0 then
61
+
n = n | 0xFFFFFFFFFFFF0000
62
+
end
63
+
return n
64
+
end
65
+
66
+
function intutil.signexti8(n)
67
+
if (n & 0x80) ~= 0 then
68
+
n = n | 0xFFFFFFFFFFFFFF00
44
69
end
45
70
return n
46
71
end
+31
memory.lua
+31
memory.lua
···
1
+
local memory = {}
2
+
3
+
local constants = require("constants")
4
+
5
+
function memory.new(pages)
6
+
local m = {
7
+
mem = {},
8
+
pages = pages,
9
+
}
10
+
setmetatable(m, {
11
+
__index = function(self, key)
12
+
if key >= (self.pages * constants.WASM_PAGE_SIZE) then
13
+
error("out of bounds memory access")
14
+
end
15
+
return self.mem[key] or 0
16
+
end,
17
+
__newindex = function(self, key, value)
18
+
if key < (self.pages * constants.WASM_PAGE_SIZE) then
19
+
self.mem[key] = value
20
+
else
21
+
error("out of bounds memory access")
22
+
end
23
+
end,
24
+
__len = function(self)
25
+
return self.pages
26
+
end,
27
+
})
28
+
return m
29
+
end
30
+
31
+
return memory
+14
ops.lua
+14
ops.lua
···
357
357
return ((a >> c) | (a << (32 - c))) & constants.I32_MAX
358
358
end
359
359
360
+
--[[ int conversions ]]
361
+
362
+
function ops.i32_wrap_i64(a)
363
+
return a & constants.I32_MAX
364
+
end
365
+
366
+
function ops.i64_extend_i32_s(a)
367
+
return intutil.signexti32(a)
368
+
end
369
+
370
+
function ops.i64_extend_i32_u(a)
371
+
return a
372
+
end
373
+
360
374
return ops
+237
-35
wasmlib.lua
+237
-35
wasmlib.lua
···
10
10
stackFrames = {},
11
11
functions = {},
12
12
types = {},
13
+
memory = {},
14
+
globals = {},
13
15
}
14
-
15
-
function wasmlib.VM:topFrame()
16
-
return self.stackFrames[#self.stackFrames]
17
-
end
18
16
19
17
function wasmlib.VM:new()
20
18
local vm = {}
···
22
20
return vm
23
21
end
24
22
23
+
function wasmlib.VM:topFrame()
24
+
return self.stackFrames[#self.stackFrames]
25
+
end
26
+
25
27
function wasmlib.VM:triop(f)
26
28
local c = table.remove(self.stack)
27
29
local b = table.remove(self.stack)
···
43
45
function wasmlib.VM:readarg8()
44
46
local curFrame = self.topFrame()
45
47
local body = self.functions[curFrame.funcIndex].body
46
-
local result = body[curFrame.pc + 1]
48
+
local result = body[curFrame.pc]
47
49
curFrame.pc = curFrame.pc + 1
48
50
return result
49
51
end
···
51
53
function wasmlib.VM:readarg32()
52
54
local curFrame = self:topFrame()
53
55
local body = self.functions[curFrame.funcIndex].body
54
-
local result = intutil.fromle32(body, curFrame.pc + 1)
56
+
local result = intutil.fromle32(body, curFrame.pc)
55
57
curFrame.pc = curFrame.pc + 4
56
58
return result
57
59
end
58
60
61
+
function wasmlib.VM:readarg64()
62
+
local curFrame = self:topFrame()
63
+
local body = self.functions[curFrame.funcIndex].body
64
+
local result = intutil.fromle64(body, curFrame.pc)
65
+
curFrame.pc = curFrame.pc + 8
66
+
return result
67
+
end
68
+
59
69
function wasmlib.VM:local_get()
60
70
local curFrame = self:topFrame()
61
71
local localIdx = self:readarg32()
···
73
83
curFrame.locals[localIdx] = localVal
74
84
end
75
85
86
+
function wasmlib.VM:local_tee()
87
+
local curFrame = self:topFrame()
88
+
local localIdx = self:readarg32()
89
+
local localVal = self.stack[#self.stack]
90
+
curFrame.locals[localIdx] = localVal
91
+
end
92
+
93
+
function wasmlib.VM:global_get()
94
+
local globalIdx = self:readarg32()
95
+
local globalVal = self.globals[globalIdx]
96
+
if globalVal == nil then
97
+
error("read invalid global")
98
+
end
99
+
table.insert(self.stack, globalVal)
100
+
end
101
+
102
+
function wasmlib.VM:global_set()
103
+
local globalIdx = self:readarg32()
104
+
local globalVal = table.remove(self.stack)
105
+
self.globals[globalIdx] = globalVal
106
+
end
107
+
76
108
function wasmlib.VM:call()
77
109
local funcIdx = self:readarg32()
78
110
self:invoke(funcIdx)
79
111
end
80
112
113
+
function wasmlib.VM:memory_size()
114
+
self:readarg8() -- always zero in WASM 1.0
115
+
return #self.memory
116
+
end
117
+
118
+
function wasmlib.VM:memory_grow()
119
+
self:readarg8() -- always zero in WASM 1.0
120
+
local amount = table.remove(self.stack)
121
+
if (
122
+
(self.memory.maxpages ~= nil) and (#self.memory + amount > self.memory.maxpages)
123
+
) or (#self.memory + amount > constants.I32_MAX)
124
+
then
125
+
table.insert(self.stack, constants.I32_MAX) -- i32 -1
126
+
else
127
+
self.memory.pages = #self.memory + amount
128
+
table.insert(self.stack, #self.memory)
129
+
end
130
+
end
131
+
132
+
function wasmlib.VM:i32_load()
133
+
self:readarg32() -- alignment, ignored for now
134
+
local offset = self:readarg32()
135
+
local value = intutil.fromle32(self.memory, offset)
136
+
table.insert(self.stack, value)
137
+
end
138
+
139
+
function wasmlib.VM:i64_load()
140
+
self:readarg32() -- alignment, ignored for now
141
+
local offset = self:readarg32()
142
+
local value = intutil.fromle64(self.memory, offset)
143
+
table.insert(self.stack, value)
144
+
end
145
+
146
+
function wasmlib.VM:i32_load8_s()
147
+
self:readarg32() -- alignment, ignored for now
148
+
local offset = self:readarg32()
149
+
local value = intutil.signexti8(self.memory[offset]) & constants.I32_MAX
150
+
table.insert(self.stack, value)
151
+
end
152
+
153
+
function wasmlib.VM:i32_load8_u()
154
+
self:readarg32() -- alignment, ignored for now
155
+
local offset = self:readarg32()
156
+
local value = self.memory[offset]
157
+
table.insert(self.stack, value)
158
+
end
159
+
160
+
function wasmlib.VM:i32_load16_s()
161
+
self:readarg32() -- alignment, ignored for now
162
+
local offset = self:readarg32()
163
+
local value = intutil.signexti16(intutil.fromle16(self.memory, offset)) & constants.I32_MAX
164
+
table.insert(self.stack, value)
165
+
end
166
+
167
+
function wasmlib.VM:i32_load16_u()
168
+
self:readarg32() -- alignment, ignored for now
169
+
local offset = self:readarg32()
170
+
local value = intutil.fromle16(self.memory, offset)
171
+
table.insert(self.stack, value)
172
+
end
173
+
174
+
function wasmlib.VM:i64_load8_s()
175
+
self:readarg32() -- alignment, ignored for now
176
+
local offset = self:readarg32()
177
+
local value = intutil.signexti8(self.memory[offset])
178
+
table.insert(self.stack, value)
179
+
end
180
+
181
+
function wasmlib.VM:i64_load8_u()
182
+
self:readarg32() -- alignment, ignored for now
183
+
local offset = self:readarg32()
184
+
local value = self.memory[offset]
185
+
table.insert(self.stack, value)
186
+
end
187
+
188
+
function wasmlib.VM:i64_load16_s()
189
+
self:readarg32() -- alignment, ignored for now
190
+
local offset = self:readarg32()
191
+
local value = intutil.signexti16(intutil.fromle16(self.memory, offset))
192
+
table.insert(self.stack, value)
193
+
end
194
+
195
+
function wasmlib.VM:i64_load16_u()
196
+
self:readarg32() -- alignment, ignored for now
197
+
local offset = self:readarg32()
198
+
local value = intutil.fromle16(self.memory, offset)
199
+
table.insert(self.stack, value)
200
+
end
201
+
202
+
function wasmlib.VM:i64_load32_s()
203
+
self:readarg32() -- alignment, ignored for now
204
+
local offset = self:readarg32()
205
+
local value = intutil.signexti32(intutil.fromle32(self.memory, offset))
206
+
table.insert(self.stack, value)
207
+
end
208
+
209
+
function wasmlib.VM:i64_load32_u()
210
+
self:readarg32() -- alignment, ignored for now
211
+
local offset = self:readarg32()
212
+
local value = intutil.fromle32(self.memory, offset)
213
+
table.insert(self.stack, value)
214
+
end
215
+
216
+
function wasmlib.VM:i64_load()
217
+
self:readarg32() -- alignment, ignored for now
218
+
local offset = self:readarg32()
219
+
local value = intutil.signexti16(intutil.fromle16(self.memory, offset))
220
+
table.insert(self.stack, value)
221
+
end
222
+
223
+
function wasmlib.VM:i32_store()
224
+
self:readarg32() -- alignment, ignored for now
225
+
local offset = self:readarg32()
226
+
local value = table.remove(self.stack)
227
+
intutil.tole32(self.memory, offset, value)
228
+
end
229
+
230
+
function wasmlib.VM:i64_store()
231
+
self:readarg32() -- alignment, ignored for now
232
+
local offset = self:readarg32()
233
+
local value = table.remove(self.stack)
234
+
intutil.tole64(self.memory, offset, value)
235
+
end
236
+
237
+
function wasmlib.VM:i32_store8()
238
+
self:readarg32() -- alignment, ignored for now
239
+
local offset = self:readarg32()
240
+
local value = table.remove(self.stack)
241
+
self.memory[offset] = value & 0xFF
242
+
end
243
+
244
+
function wasmlib.VM:i32_store16()
245
+
self:readarg32() -- alignment, ignored for now
246
+
local offset = self:readarg32()
247
+
local value = table.remove(self.stack)
248
+
intutil.tole16(self.memory, offset, value)
249
+
end
250
+
251
+
function wasmlib.VM:i64_store8()
252
+
self:readarg32() -- alignment, ignored for now
253
+
local offset = self:readarg32()
254
+
local value = table.remove(self.stack)
255
+
self.memory[offset] = value & 0xFF
256
+
end
257
+
258
+
function wasmlib.VM:i64_store16()
259
+
self:readarg32() -- alignment, ignored for now
260
+
local offset = self:readarg32()
261
+
local value = table.remove(self.stack)
262
+
intutil.tole16(self.memory, offset, value)
263
+
end
264
+
265
+
function wasmlib.VM:i64_store32()
266
+
self:readarg32() -- alignment, ignored for now
267
+
local offset = self:readarg32()
268
+
local value = table.remove(self.stack)
269
+
intutil.tole32(self.memory, offset, value)
270
+
end
271
+
272
+
function wasmlib.VM:i32_const()
273
+
table.insert(self.stack, self:readarg32())
274
+
end
275
+
276
+
function wasmlib.VM:i64_const()
277
+
table.insert(self.stack, self:readarg64())
278
+
end
279
+
81
280
function wasmlib.VM:step()
82
281
local curFrame = self:topFrame()
83
282
local body = self.functions[curFrame.funcIndex].body
84
283
local opcode = body[curFrame.pc]
284
+
curFrame.pc = curFrame.pc + 1
85
285
86
286
local c = constants.opcodes
87
287
local optable = {
···
105
305
-- variable
106
306
[c.OP_LOCAL_GET] = function() self:local_get() end,
107
307
[c.OP_LOCAL_SET] = function() self:local_set() end,
108
-
-- LOCAL_TEE
109
-
-- GLOBAL_GET
110
-
-- GLOBAL_SET
308
+
[c.OP_LOCAL_TEE] = function() self:local_tee() end,
309
+
[c.OP_GLOBAL_GET] = function() self:global_get() end,
310
+
[c.OP_GLOBAL_SET] = function() self:global_set() end,
111
311
-- memory
112
-
-- I32_LOAD
113
-
-- I64_LOAD
312
+
[c.OP_I32_LOAD] = function() self:i32_load() end,
313
+
[c.OP_I64_LOAD] = function() self:i64_load() end,
114
314
-- [float instrs]
115
-
-- I32_LOAD8_S
116
-
-- I32_LOAD8_U
117
-
-- I32_LOAD16_S
118
-
-- I32_LOAD16_U
119
-
-- I64_LOAD8_S
120
-
-- I64_LOAD8_U
121
-
-- I64_LOAD16_S
122
-
-- I64_LOAD16_U
123
-
-- I64_LOAD32_S
124
-
-- I64_LOAD32_U
125
-
-- I32_STORE
126
-
-- I64_STORE
315
+
[c.OP_I32_LOAD8_S] = function() self:i32_load8_s() end,
316
+
[c.OP_I32_LOAD8_U] = function() self:i32_load8_u() end,
317
+
[c.OP_I32_LOAD16_S] = function() self:i32_load16_s() end,
318
+
[c.OP_I32_LOAD16_U] = function() self:i32_load16_u() end,
319
+
[c.OP_I64_LOAD8_S] = function() self:i64_load8_s() end,
320
+
[c.OP_I64_LOAD8_U] = function() self:i64_load8_u() end,
321
+
[c.OP_I64_LOAD16_S] = function() self:i64_load16_s() end,
322
+
[c.OP_I64_LOAD16_U] = function() self:i64_load16_u() end,
323
+
[c.OP_I64_LOAD32_S] = function() self:i64_load32_s() end,
324
+
[c.OP_I64_LOAD32_U] = function() self:i64_load32_u() end,
325
+
[c.OP_I32_STORE] = function() self:i32_store() end,
326
+
[c.OP_I64_STORE] = function() self:i64_store() end,
127
327
-- [floart instrs]
128
-
-- I32_STORE8
129
-
-- I32_STORE16
130
-
-- I64_STORE8
131
-
-- I64_STORE16
132
-
-- I64_STORE32
133
-
-- MEMORY_SIZE
134
-
-- MEMORY_GROW
328
+
[c.OP_I32_STORE8] = function() self:i32_store8() end,
329
+
[c.OP_I32_STORE16] = function() self:i32_store16() end,
330
+
[c.OP_I64_STORE8] = function() self:i64_store8() end,
331
+
[c.OP_I64_STORE16] = function() self:i64_store16() end,
332
+
[c.OP_I64_STORE32] = function() self:i64_store32() end,
333
+
[c.OP_MEMORY_SIZE] = function() self:memory_size() end,
334
+
[c.OP_MEMORY_GROW] = function() self:memory_grow() end,
335
+
-- constants
336
+
[c.OP_I32_CONST] = function() self:i32_const() end,
337
+
[c.OP_I64_CONST] = function() self:i64_const() end,
338
+
-- [float consts]
135
339
-- i32 comparisons
136
340
[c.OP_I32_EQZ] = function() self:unop (ops.i32_eqz) end,
137
341
[c.OP_I32_EQ] = function() self:binop(ops.i32_eq) end,
···
195
399
[c.OP_I64_ROTR] = function() self:binop(ops.i64_rotr) end,
196
400
-- [float operations]
197
401
-- conversions
198
-
-- I32_WRAP_I64
402
+
[c.OP_I32_WRAP_I64] = function() self:unop(ops.i32_wrap_i64) end,
199
403
-- [float stuff]
200
-
-- I64_EXTEND_I32_S
201
-
-- I64_EXTEND_I32_U
404
+
[c.OP_I64_EXTEND_I32_S] = function() self:unop(ops.i64_extend_i32_s) end,
405
+
[c.OP_I64_EXTEND_I32_U] = function() self:unop(ops.i64_extend_i32_u) end,
202
406
-- [float stuff]
203
407
}
204
408
···
207
411
error("unimplemented")
208
412
end
209
413
opfunc()
210
-
211
-
curFrame.pc = curFrame.pc + 1
212
414
end
213
415
214
416
function wasmlib.VM:invoke(funcIndex)