nmigen/test/test_hdl_ast.py

   1 from enum import Enum
   2
   3 from ..hdl.ast import *
   4 from .tools import *
   5
   6
   7 class ValueTestCase(FHDLTestCase):
   8     def test_wrap(self):
   9         self.assertIsInstance(Value.wrap(0), Const)
  10         self.assertIsInstance(Value.wrap(True), Const)
  11         c = Const(0)
  12         self.assertIs(Value.wrap(c), c)
  13         with self.assertRaises(TypeError,
  14                 msg="Object ''str'' is not an nMigen value"):
  15             Value.wrap("str")
  16
  17     def test_bool(self):
  18         with self.assertRaises(TypeError,
  19                 msg="Attempted to convert nMigen value to boolean"):
  20             if Const(0):
  21                 pass
  22
  23     def test_len(self):
  24         self.assertEqual(len(Const(10)), 4)
  25
  26     def test_getitem_int(self):
  27         s1 = Const(10)[0]
  28         self.assertIsInstance(s1, Slice)
  29         self.assertEqual(s1.start, 0)
  30         self.assertEqual(s1.end, 1)
  31         s2 = Const(10)[-1]
  32         self.assertIsInstance(s2, Slice)
  33         self.assertEqual(s2.start, 3)
  34         self.assertEqual(s2.end, 4)
  35         with self.assertRaises(IndexError,
  36                 msg="Cannot index 5 bits into 4-bit value"):
  37             Const(10)[5]
  38
  39     def test_getitem_slice(self):
  40         s1 = Const(10)[1:3]
  41         self.assertIsInstance(s1, Slice)
  42         self.assertEqual(s1.start, 1)
  43         self.assertEqual(s1.end, 3)
  44         s2 = Const(10)[1:-2]
  45         self.assertIsInstance(s2, Slice)
  46         self.assertEqual(s2.start, 1)
  47         self.assertEqual(s2.end, 2)
  48         s3 = Const(31)[::2]
  49         self.assertIsInstance(s3, Cat)
  50         self.assertIsInstance(s3.parts[0], Slice)
  51         self.assertEqual(s3.parts[0].start, 0)
  52         self.assertEqual(s3.parts[0].end, 1)
  53         self.assertIsInstance(s3.parts[1], Slice)
  54         self.assertEqual(s3.parts[1].start, 2)
  55         self.assertEqual(s3.parts[1].end, 3)
  56         self.assertIsInstance(s3.parts[2], Slice)
  57         self.assertEqual(s3.parts[2].start, 4)
  58         self.assertEqual(s3.parts[2].end, 5)
  59
  60     def test_getitem_wrong(self):
  61         with self.assertRaises(TypeError,
  62                 msg="Cannot index value with 'str'"):
  63             Const(31)["str"]
  64
  65
  66 class ConstTestCase(FHDLTestCase):
  67     def test_shape(self):
  68         self.assertEqual(Const(0).shape(),   (1, False))
  69         self.assertEqual(Const(1).shape(),   (1, False))
  70         self.assertEqual(Const(10).shape(),  (4, False))
  71         self.assertEqual(Const(-10).shape(), (5, True))
  72
  73         self.assertEqual(Const(1, 4).shape(),          (4, False))
  74         self.assertEqual(Const(1, (4, True)).shape(),  (4, True))
  75         self.assertEqual(Const(0, (0, False)).shape(), (0, False))
  76
  77     def test_shape_bad(self):
  78         with self.assertRaises(TypeError,
  79                 msg="Width must be a non-negative integer, not '-1'"):
  80             Const(1, -1)
  81
  82     def test_normalization(self):
  83         self.assertEqual(Const(0b10110, (5, True)).value, -10)
  84
  85     def test_value(self):
  86         self.assertEqual(Const(10).value, 10)
  87
  88     def test_repr(self):
  89         self.assertEqual(repr(Const(10)),  "(const 4'd10)")
  90         self.assertEqual(repr(Const(-10)), "(const 5'sd-10)")
  91
  92     def test_hash(self):
  93         with self.assertRaises(TypeError):
  94             hash(Const(0))
  95
  96
  97 class OperatorTestCase(FHDLTestCase):
  98     def test_bool(self):
  99         v = Const(0, 4).bool()
 100         self.assertEqual(repr(v), "(b (const 4'd0))")
 101         self.assertEqual(v.shape(), (1, False))
 102
 103     def test_invert(self):
 104         v = ~Const(0, 4)
 105         self.assertEqual(repr(v), "(~ (const 4'd0))")
 106         self.assertEqual(v.shape(), (4, False))
 107
 108     def test_neg(self):
 109         v1 = -Const(0, (4, False))
 110         self.assertEqual(repr(v1), "(- (const 4'd0))")
 111         self.assertEqual(v1.shape(), (5, True))
 112         v2 = -Const(0, (4, True))
 113         self.assertEqual(repr(v2), "(- (const 4'sd0))")
 114         self.assertEqual(v2.shape(), (4, True))
 115
 116     def test_add(self):
 117         v1 = Const(0, (4, False)) + Const(0, (6, False))
 118         self.assertEqual(repr(v1), "(+ (const 4'd0) (const 6'd0))")
 119         self.assertEqual(v1.shape(), (7, False))
 120         v2 = Const(0, (4, True)) + Const(0, (6, True))
 121         self.assertEqual(v2.shape(), (7, True))
 122         v3 = Const(0, (4, True)) + Const(0, (4, False))
 123         self.assertEqual(v3.shape(), (6, True))
 124         v4 = Const(0, (4, False)) + Const(0, (4, True))
 125         self.assertEqual(v4.shape(), (6, True))
 126         v5 = 10 + Const(0, 4)
 127         self.assertEqual(v5.shape(), (5, False))
 128
 129     def test_sub(self):
 130         v1 = Const(0, (4, False)) - Const(0, (6, False))
 131         self.assertEqual(repr(v1), "(- (const 4'd0) (const 6'd0))")
 132         self.assertEqual(v1.shape(), (7, False))
 133         v2 = Const(0, (4, True)) - Const(0, (6, True))
 134         self.assertEqual(v2.shape(), (7, True))
 135         v3 = Const(0, (4, True)) - Const(0, (4, False))
 136         self.assertEqual(v3.shape(), (6, True))
 137         v4 = Const(0, (4, False)) - Const(0, (4, True))
 138         self.assertEqual(v4.shape(), (6, True))
 139         v5 = 10 - Const(0, 4)
 140         self.assertEqual(v5.shape(), (5, False))
 141
 142     def test_mul(self):
 143         v1 = Const(0, (4, False)) * Const(0, (6, False))
 144         self.assertEqual(repr(v1), "(* (const 4'd0) (const 6'd0))")
 145         self.assertEqual(v1.shape(), (10, False))
 146         v2 = Const(0, (4, True)) * Const(0, (6, True))
 147         self.assertEqual(v2.shape(), (10, True))
 148         v3 = Const(0, (4, True)) * Const(0, (4, False))
 149         self.assertEqual(v3.shape(), (8, True))
 150         v5 = 10 * Const(0, 4)
 151         self.assertEqual(v5.shape(), (8, False))
 152
 153     def test_and(self):
 154         v1 = Const(0, (4, False)) & Const(0, (6, False))
 155         self.assertEqual(repr(v1), "(& (const 4'd0) (const 6'd0))")
 156         self.assertEqual(v1.shape(), (6, False))
 157         v2 = Const(0, (4, True)) & Const(0, (6, True))
 158         self.assertEqual(v2.shape(), (6, True))
 159         v3 = Const(0, (4, True)) & Const(0, (4, False))
 160         self.assertEqual(v3.shape(), (5, True))
 161         v4 = Const(0, (4, False)) & Const(0, (4, True))
 162         self.assertEqual(v4.shape(), (5, True))
 163         v5 = 10 & Const(0, 4)
 164         self.assertEqual(v5.shape(), (4, False))
 165
 166     def test_or(self):
 167         v1 = Const(0, (4, False)) | Const(0, (6, False))
 168         self.assertEqual(repr(v1), "(| (const 4'd0) (const 6'd0))")
 169         self.assertEqual(v1.shape(), (6, False))
 170         v2 = Const(0, (4, True)) | Const(0, (6, True))
 171         self.assertEqual(v2.shape(), (6, True))
 172         v3 = Const(0, (4, True)) | Const(0, (4, False))
 173         self.assertEqual(v3.shape(), (5, True))
 174         v4 = Const(0, (4, False)) | Const(0, (4, True))
 175         self.assertEqual(v4.shape(), (5, True))
 176         v5 = 10 | Const(0, 4)
 177         self.assertEqual(v5.shape(), (4, False))
 178
 179     def test_xor(self):
 180         v1 = Const(0, (4, False)) ^ Const(0, (6, False))
 181         self.assertEqual(repr(v1), "(^ (const 4'd0) (const 6'd0))")
 182         self.assertEqual(v1.shape(), (6, False))
 183         v2 = Const(0, (4, True)) ^ Const(0, (6, True))
 184         self.assertEqual(v2.shape(), (6, True))
 185         v3 = Const(0, (4, True)) ^ Const(0, (4, False))
 186         self.assertEqual(v3.shape(), (5, True))
 187         v4 = Const(0, (4, False)) ^ Const(0, (4, True))
 188         self.assertEqual(v4.shape(), (5, True))
 189         v5 = 10 ^ Const(0, 4)
 190         self.assertEqual(v5.shape(), (4, False))
 191
 192     def test_shl(self):
 193         v1 = Const(1, 4) << Const(4)
 194         self.assertEqual(repr(v1), "(<< (const 4'd1) (const 3'd4))")
 195         self.assertEqual(v1.shape(), (11, False))
 196         v2 = Const(1, 4) << Const(-3)
 197         self.assertEqual(v2.shape(), (7, False))
 198
 199     def test_shr(self):
 200         v1 = Const(1, 4) >> Const(4)
 201         self.assertEqual(repr(v1), "(>> (const 4'd1) (const 3'd4))")
 202         self.assertEqual(v1.shape(), (4, False))
 203         v2 = Const(1, 4) >> Const(-3)
 204         self.assertEqual(v2.shape(), (8, False))
 205
 206     def test_lt(self):
 207         v = Const(0, 4) < Const(0, 6)
 208         self.assertEqual(repr(v), "(< (const 4'd0) (const 6'd0))")
 209         self.assertEqual(v.shape(), (1, False))
 210
 211     def test_le(self):
 212         v = Const(0, 4) <= Const(0, 6)
 213         self.assertEqual(repr(v), "(<= (const 4'd0) (const 6'd0))")
 214         self.assertEqual(v.shape(), (1, False))
 215
 216     def test_gt(self):
 217         v = Const(0, 4) > Const(0, 6)
 218         self.assertEqual(repr(v), "(> (const 4'd0) (const 6'd0))")
 219         self.assertEqual(v.shape(), (1, False))
 220
 221     def test_ge(self):
 222         v = Const(0, 4) >= Const(0, 6)
 223         self.assertEqual(repr(v), "(>= (const 4'd0) (const 6'd0))")
 224         self.assertEqual(v.shape(), (1, False))
 225
 226     def test_eq(self):
 227         v = Const(0, 4) == Const(0, 6)
 228         self.assertEqual(repr(v), "(== (const 4'd0) (const 6'd0))")
 229         self.assertEqual(v.shape(), (1, False))
 230
 231     def test_ne(self):
 232         v = Const(0, 4) != Const(0, 6)
 233         self.assertEqual(repr(v), "(!= (const 4'd0) (const 6'd0))")
 234         self.assertEqual(v.shape(), (1, False))
 235
 236     def test_mux(self):
 237         s  = Const(0)
 238         v1 = Mux(s, Const(0, (4, False)), Const(0, (6, False)))
 239         self.assertEqual(repr(v1), "(m (const 1'd0) (const 4'd0) (const 6'd0))")
 240         self.assertEqual(v1.shape(), (6, False))
 241         v2 = Mux(s, Const(0, (4, True)), Const(0, (6, True)))
 242         self.assertEqual(v2.shape(), (6, True))
 243         v3 = Mux(s, Const(0, (4, True)), Const(0, (4, False)))
 244         self.assertEqual(v3.shape(), (5, True))
 245         v4 = Mux(s, Const(0, (4, False)), Const(0, (4, True)))
 246         self.assertEqual(v4.shape(), (5, True))
 247
 248     def test_bool(self):
 249         v = Const(0).bool()
 250         self.assertEqual(repr(v), "(b (const 1'd0))")
 251         self.assertEqual(v.shape(), (1, False))
 252
 253     def test_hash(self):
 254         with self.assertRaises(TypeError):
 255             hash(Const(0) + Const(0))
 256
 257
 258 class SliceTestCase(FHDLTestCase):
 259     def test_shape(self):
 260         s1 = Const(10)[2]
 261         self.assertEqual(s1.shape(), (1, False))
 262         s2 = Const(-10)[0:2]
 263         self.assertEqual(s2.shape(), (2, False))
 264
 265     def test_start_end_negative(self):
 266         c  = Const(0, 8)
 267         s1 = Slice(c, 0, -1)
 268         self.assertEqual((s1.start, s1.end), (0, 7))
 269         s1 = Slice(c, -4, -1)
 270         self.assertEqual((s1.start, s1.end), (4, 7))
 271
 272     def test_start_end_wrong(self):
 273         with self.assertRaises(TypeError,
 274                 msg="Slice start must be an integer, not ''x''"):
 275             Slice(0, "x", 1)
 276         with self.assertRaises(TypeError,
 277                 msg="Slice end must be an integer, not ''x''"):
 278             Slice(0, 1, "x")
 279
 280     def test_start_end_out_of_range(self):
 281         c = Const(0, 8)
 282         with self.assertRaises(IndexError,
 283                 msg="Cannot start slice 10 bits into 8-bit value"):
 284             Slice(c, 10, 12)
 285         with self.assertRaises(IndexError,
 286                 msg="Cannot end slice 12 bits into 8-bit value"):
 287             Slice(c, 0, 12)
 288         with self.assertRaises(IndexError,
 289                 msg="Slice start 4 must be less than slice end 2"):
 290             Slice(c, 4, 2)
 291
 292     def test_repr(self):
 293         s1 = Const(10)[2]
 294         self.assertEqual(repr(s1), "(slice (const 4'd10) 2:3)")
 295
 296
 297 class PartTestCase(FHDLTestCase):
 298     def setUp(self):
 299         self.c = Const(0, 8)
 300         self.s = Signal(max=self.c.nbits)
 301
 302     def test_shape(self):
 303         s1 = self.c.part(self.s, 2)
 304         self.assertEqual(s1.shape(), (2, False))
 305         s2 = self.c.part(self.s, 0)
 306         self.assertEqual(s2.shape(), (0, False))
 307
 308     def test_width_bad(self):
 309         with self.assertRaises(TypeError):
 310             self.c.part(self.s, -1)
 311
 312     def test_repr(self):
 313         s = self.c.part(self.s, 2)
 314         self.assertEqual(repr(s), "(part (const 8'd0) (sig s) 2)")
 315
 316
 317 class CatTestCase(FHDLTestCase):
 318     def test_shape(self):
 319         c0 = Cat()
 320         self.assertEqual(c0.shape(), (0, False))
 321         c1 = Cat(Const(10))
 322         self.assertEqual(c1.shape(), (4, False))
 323         c2 = Cat(Const(10), Const(1))
 324         self.assertEqual(c2.shape(), (5, False))
 325         c3 = Cat(Const(10), Const(1), Const(0))
 326         self.assertEqual(c3.shape(), (6, False))
 327
 328     def test_repr(self):
 329         c1 = Cat(Const(10), Const(1))
 330         self.assertEqual(repr(c1), "(cat (const 4'd10) (const 1'd1))")
 331
 332
 333 class ReplTestCase(FHDLTestCase):
 334     def test_shape(self):
 335         s1 = Repl(Const(10), 3)
 336         self.assertEqual(s1.shape(), (12, False))
 337         s2 = Repl(Const(10), 0)
 338         self.assertEqual(s2.shape(), (0, False))
 339
 340     def test_count_wrong(self):
 341         with self.assertRaises(TypeError):
 342             Repl(Const(10), -1)
 343         with self.assertRaises(TypeError):
 344             Repl(Const(10), "str")
 345
 346     def test_repr(self):
 347         s = Repl(Const(10), 3)
 348         self.assertEqual(repr(s), "(repl (const 4'd10) 3)")
 349
 350
 351 class ArrayTestCase(FHDLTestCase):
 352     def test_acts_like_array(self):
 353         a = Array([1,2,3])
 354         self.assertSequenceEqual(a, [1,2,3])
 355         self.assertEqual(a[1], 2)
 356         a[1] = 4
 357         self.assertSequenceEqual(a, [1,4,3])
 358         del a[1]
 359         self.assertSequenceEqual(a, [1,3])
 360         a.insert(1, 2)
 361         self.assertSequenceEqual(a, [1,2,3])
 362
 363     def test_becomes_immutable(self):
 364         a = Array([1,2,3])
 365         s1 = Signal(max=len(a))
 366         s2 = Signal(max=len(a))
 367         v1 = a[s1]
 368         v2 = a[s2]
 369         with self.assertRaisesRegex(ValueError,
 370                 regex=r"^Array can no longer be mutated after it was indexed with a value at "):
 371             a[1] = 2
 372         with self.assertRaisesRegex(ValueError,
 373                 regex=r"^Array can no longer be mutated after it was indexed with a value at "):
 374             del a[1]
 375         with self.assertRaisesRegex(ValueError,
 376                 regex=r"^Array can no longer be mutated after it was indexed with a value at "):
 377             a.insert(1, 2)
 378
 379     def test_repr(self):
 380         a = Array([1,2,3])
 381         self.assertEqual(repr(a), "(array mutable [1, 2, 3])")
 382         s = Signal(max=len(a))
 383         v = a[s]
 384         self.assertEqual(repr(a), "(array [1, 2, 3])")
 385
 386
 387 class ArrayProxyTestCase(FHDLTestCase):
 388     def test_index_shape(self):
 389         m = Array(Array(x * y for y in range(1, 4)) for x in range(1, 4))
 390         a = Signal(max=3)
 391         b = Signal(max=3)
 392         v = m[a][b]
 393         self.assertEqual(v.shape(), (4, False))
 394
 395     def test_attr_shape(self):
 396         from collections import namedtuple
 397         pair = namedtuple("pair", ("p", "n"))
 398         a = Array(pair(i, -i) for i in range(10))
 399         s = Signal(max=len(a))
 400         v = a[s]
 401         self.assertEqual(v.p.shape(), (4, False))
 402         self.assertEqual(v.n.shape(), (6, True))
 403
 404     def test_repr(self):
 405         a = Array([1, 2, 3])
 406         s = Signal(max=3)
 407         v = a[s]
 408         self.assertEqual(repr(v), "(proxy (array [1, 2, 3]) (sig s))")
 409
 410
 411 class SignalTestCase(FHDLTestCase):
 412     def test_shape(self):
 413         s1 = Signal()
 414         self.assertEqual(s1.shape(), (1, False))
 415         s2 = Signal(2)
 416         self.assertEqual(s2.shape(), (2, False))
 417         s3 = Signal((2, False))
 418         self.assertEqual(s3.shape(), (2, False))
 419         s4 = Signal((2, True))
 420         self.assertEqual(s4.shape(), (2, True))
 421         s5 = Signal(max=16)
 422         self.assertEqual(s5.shape(), (4, False))
 423         s6 = Signal(min=4, max=16)
 424         self.assertEqual(s6.shape(), (4, False))
 425         s7 = Signal(min=-4, max=16)
 426         self.assertEqual(s7.shape(), (5, True))
 427         s8 = Signal(min=-20, max=16)
 428         self.assertEqual(s8.shape(), (6, True))
 429         s9 = Signal(0)
 430         self.assertEqual(s9.shape(), (0, False))
 431         s10 = Signal(max=1)
 432         self.assertEqual(s10.shape(), (0, False))
 433
 434     def test_shape_bad(self):
 435         with self.assertRaises(ValueError,
 436                 msg="Lower bound 10 should be less or equal to higher bound 4"):
 437             Signal(min=10, max=4)
 438         with self.assertRaises(ValueError,
 439                 msg="Only one of bits/signedness or bounds may be specified"):
 440             Signal(2, min=10)
 441         with self.assertRaises(TypeError,
 442                 msg="Width must be a non-negative integer, not '-10'"):
 443             Signal(-10)
 444
 445     def test_name(self):
 446         s1 = Signal()
 447         self.assertEqual(s1.name, "s1")
 448         s2 = Signal(name="sig")
 449         self.assertEqual(s2.name, "sig")
 450
 451     def test_name_bad(self):
 452         with self.assertRaises(TypeError,
 453                 msg="Name must be a string, not 'True'"):
 454             # A common typo: forgetting to put parens around width and signedness
 455             Signal(1, True)
 456
 457     def test_reset(self):
 458         s1 = Signal(4, reset=0b111, reset_less=True)
 459         self.assertEqual(s1.reset, 0b111)
 460         self.assertEqual(s1.reset_less, True)
 461
 462     def test_attrs(self):
 463         s1 = Signal()
 464         self.assertEqual(s1.attrs, {})
 465         s2 = Signal(attrs={"no_retiming": True})
 466         self.assertEqual(s2.attrs, {"no_retiming": True})
 467
 468     def test_repr(self):
 469         s1 = Signal()
 470         self.assertEqual(repr(s1), "(sig s1)")
 471
 472     def test_like(self):
 473         s1 = Signal.like(Signal(4))
 474         self.assertEqual(s1.shape(), (4, False))
 475         s2 = Signal.like(Signal(min=-15))
 476         self.assertEqual(s2.shape(), (5, True))
 477         s3 = Signal.like(Signal(4, reset=0b111, reset_less=True))
 478         self.assertEqual(s3.reset, 0b111)
 479         self.assertEqual(s3.reset_less, True)
 480         s4 = Signal.like(Signal(attrs={"no_retiming": True}))
 481         self.assertEqual(s4.attrs, {"no_retiming": True})
 482         s5 = Signal.like(Signal(decoder=str))
 483         self.assertEqual(s5.decoder, str)
 484         s6 = Signal.like(10)
 485         self.assertEqual(s6.shape(), (4, False))
 486         s7 = [Signal.like(Signal(4))][0]
 487         self.assertEqual(s7.name, "$like")
 488         s8 = Signal.like(s1, name_suffix="_ff")
 489         self.assertEqual(s8.name, "s1_ff")
 490
 491     def test_decoder(self):
 492         class Color(Enum):
 493             RED  = 1
 494             BLUE = 2
 495         s = Signal(decoder=Color)
 496         self.assertEqual(s.decoder(1), "RED/1")
 497         self.assertEqual(s.decoder(3), "3")
 498
 499
 500 class ClockSignalTestCase(FHDLTestCase):
 501     def test_domain(self):
 502         s1 = ClockSignal()
 503         self.assertEqual(s1.domain, "sync")
 504         s2 = ClockSignal("pix")
 505         self.assertEqual(s2.domain, "pix")
 506
 507         with self.assertRaises(TypeError,
 508                 msg="Clock domain name must be a string, not '1'"):
 509             ClockSignal(1)
 510
 511     def test_shape(self):
 512         self.assertEqual(ClockSignal().shape(), (1, False))
 513
 514     def test_repr(self):
 515         s1 = ClockSignal()
 516         self.assertEqual(repr(s1), "(clk sync)")
 517
 518
 519 class ResetSignalTestCase(FHDLTestCase):
 520     def test_domain(self):
 521         s1 = ResetSignal()
 522         self.assertEqual(s1.domain, "sync")
 523         s2 = ResetSignal("pix")
 524         self.assertEqual(s2.domain, "pix")
 525
 526         with self.assertRaises(TypeError,
 527                 msg="Clock domain name must be a string, not '1'"):
 528             ResetSignal(1)
 529
 530     def test_shape(self):
 531         self.assertEqual(ResetSignal().shape(), (1, False))
 532
 533     def test_repr(self):
 534         s1 = ResetSignal()
 535         self.assertEqual(repr(s1), "(rst sync)")
 536
 537
 538 class MockUserValue(UserValue):
 539     def __init__(self, lowered):
 540         super().__init__()
 541         self.lower_count = 0
 542         self.lowered     = lowered
 543
 544     def lower(self):
 545         self.lower_count += 1
 546         return self.lowered
 547
 548
 549 class UserValueTestCase(FHDLTestCase):
 550     def test_shape(self):
 551         uv = MockUserValue(1)
 552         self.assertEqual(uv.shape(), (1, False))
 553         uv.lowered = 2
 554         self.assertEqual(uv.shape(), (1, False))
 555         self.assertEqual(uv.lower_count, 1)
 556
 557
 558 class SampleTestCase(FHDLTestCase):
 559     def test_const(self):
 560         s = Sample(1, 1, "sync")
 561         self.assertEqual(s.shape(), (1, False))
 562
 563     def test_signal(self):
 564         s1 = Sample(Signal(2), 1, "sync")
 565         self.assertEqual(s1.shape(), (2, False))
 566         s2 = Sample(ClockSignal(), 1, "sync")
 567         s3 = Sample(ResetSignal(), 1, "sync")
 568
 569     def test_wrong_value_operator(self):
 570         with self.assertRaises(TypeError,
 571                 "Sampled value may only be a signal or a constant, not "
 572                 "(+ (sig $signal) (const 1'd1))"):
 573             Sample(Signal() + 1, 1, "sync")
 574
 575     def test_wrong_clocks_neg(self):
 576         with self.assertRaises(ValueError,
 577                 "Cannot sample a value 1 cycles in the future"):
 578             Sample(Signal(), -1, "sync")