src/openpower/decoder/helpers.py

   1 import unittest
   2 import struct
   3 from openpower.decoder.selectable_int import (SelectableInt, onebit,
   4                                               selectconcat)
   5 from nmutil.divmod import trunc_divs, trunc_rems
   6 from operator import floordiv, mod
   7 from openpower.decoder.selectable_int import selectltu as ltu
   8 from openpower.decoder.selectable_int import selectgtu as gtu
   9 from openpower.decoder.selectable_int import check_extsign
  10
  11 from openpower.util import log
  12
  13 trunc_div = floordiv
  14 trunc_rem = mod
  15 DIVS = trunc_divs
  16 MODS = trunc_rems
  17
  18 """
  19 Links:
  20 * https://bugs.libre-soc.org/show_bug.cgi?id=324 - add trunc_div and trunc_rem
  21 """
  22
  23
  24 def exts(value, bits):
  25     sign = 1 << (bits - 1)
  26     return (value & (sign - 1)) - (value & sign)
  27
  28
  29 def EXTS(value):
  30     """ extends sign bit out from current MSB to all 256 bits
  31     """
  32     log ("EXTS", value, type(value))
  33     assert isinstance(value, SelectableInt)
  34     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  35
  36
  37 def EXTS64(value):
  38     """ extends sign bit out from current MSB to 64 bits
  39     """
  40     assert isinstance(value, SelectableInt)
  41     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  42
  43
  44 def EXTS128(value):
  45     """ extends sign bit out from current MSB to 128 bits
  46     """
  47     assert isinstance(value, SelectableInt)
  48     return SelectableInt(exts(value.value, value.bits) & ((1 << 128)-1), 128)
  49
  50
  51 # signed version of MUL
  52 def MULS(a, b):
  53     if isinstance(b, int):
  54         b = SelectableInt(b, self.bits)
  55     b = check_extsign(a, b)
  56     a_s = a.value & (1 << (a.bits-1)) != 0
  57     b_s = b.value & (1 << (b.bits-1)) != 0
  58     result = abs(a) * abs(b)
  59     log("MULS", result, a_s, b_s)
  60     if a_s == b_s:
  61         return result
  62     return -result
  63
  64
  65 # XXX should this explicitly extend from 32 to 64?
  66 def EXTZ64(value):
  67     if isinstance(value, SelectableInt):
  68         value = value.value
  69     return SelectableInt(value & ((1 << 32)-1), 64)
  70
  71
  72 def rotl(value, bits, wordlen):
  73     if isinstance(bits, SelectableInt):
  74         bits = bits.value
  75     mask = (1 << wordlen) - 1
  76     bits = bits & (wordlen - 1)
  77     return ((value << bits) | (value >> (wordlen-bits))) & mask
  78
  79
  80 def ROTL64(value, bits):
  81     return rotl(value, bits, 64)
  82
  83
  84 def ROTL32(value, bits):
  85     if isinstance(bits, SelectableInt):
  86         bits = bits.value
  87     if isinstance(value, SelectableInt):
  88         value = SelectableInt(value.value, 64)
  89     return rotl(value | (value << 32), bits, 64)
  90
  91 def MASK32(x, y):
  92     if isinstance(x, SelectableInt):
  93         x = x.value
  94     if isinstance(y, SelectableInt):
  95         y = y.value
  96     return MASK(x+32, y+32)
  97
  98 def MASK(x, y):
  99     if isinstance(x, SelectableInt):
 100         x = x.value
 101     if isinstance(y, SelectableInt):
 102         y = y.value
 103     if x < y:
 104         x = 64-x
 105         y = 63-y
 106         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
 107         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
 108     elif x == y:
 109         return 1 << (63-x)
 110     else:
 111         x = 64-x
 112         y = 63-y
 113         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
 114         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
 115     return mask_a ^ mask_b
 116
 117
 118 def ne(a, b):
 119     return onebit(a != b)
 120
 121
 122 def eq(a, b):
 123     return onebit(a == b)
 124
 125
 126 def gt(a, b):
 127     return onebit(a > b)
 128
 129
 130 def ge(a, b):
 131     return onebit(a >= b)
 132
 133
 134 def lt(a, b):
 135     return onebit(a < b)
 136
 137
 138 def le(a, b):
 139     return onebit(a <= b)
 140
 141
 142 def length(a):
 143     return len(a)
 144
 145
 146 def undefined(v):
 147     """ function that, for Power spec purposes, returns undefined bits of
 148         the same shape as the input bits.  however, for purposes of matching
 149         POWER9's behavior returns the input bits unchanged.  this effectively
 150         "marks" (tags) locations in the v3.0B spec that need to be submitted
 151         for clarification.
 152     """
 153     return v
 154
 155 def DOUBLE(WORD):
 156     """convert incoming WORD to double.  v3.0B p140 section 4.6.2
 157     """
 158     # result, FRT, start off all zeros
 159     log ("WORD", WORD)
 160     FRT = SelectableInt(0, 64)
 161     z1 = SelectableInt(0, 1)
 162     z29 = SelectableInt(0, 29)
 163     e = WORD[1:9]
 164     m = WORD[9:32]
 165     s = WORD[0]
 166     log ("word s e m", s, e, m)
 167
 168     # Normalized Operand
 169     if e.value > 0 and e.value  < 255:
 170         log ("normalised")
 171         FRT[0:2] = WORD[0:2]
 172         FRT[2] = ~WORD[1]
 173         FRT[3] = ~WORD[1]
 174         FRT[4] = ~WORD[1]
 175         FRT[5:64] = selectconcat(WORD[2:32], z29)
 176
 177         # Denormalized Operand
 178         if e.value  == 0 and m.value != 0:
 179             log ("denormalised")
 180             sign = WORD[0]
 181             exp = -126
 182             frac = selectconcat(z1, WORD[9:32], z29)
 183             # normalize the operand
 184             while frac[0].value  == 0:
 185                 frac[0:53] = selectconcat(frac[1:53], z1)
 186                 exp = exp - 1
 187             FRT[0] = sign
 188             FRT[1:12] = exp + 1023
 189             FRT[12:64] = frac[1:53]
 190
 191     # Zero / Infinity / NaN
 192     if e.value  == 255 or WORD[1:32].value  == 0:
 193         log ("z/inf/nan")
 194         FRT[0:2] = WORD[0:2]
 195         FRT[2] = WORD[1]
 196         FRT[3] = WORD[1]
 197         FRT[4] = WORD[1]
 198         FRT[5:64] = selectconcat(WORD[2:32], z29)
 199
 200     log ("Double s e m", FRT[0].value, FRT[1:12].value-1023,
 201                            FRT[12:64].value)
 202
 203     return FRT
 204
 205
 206 def SINGLE(FRS):
 207     """convert incoming FRS into 32-bit word.  v3.0B p144 section 4.6.3
 208     """
 209     # result - WORD - start off all zeros
 210     WORD = SelectableInt(0, 32)
 211
 212     e = FRS[1:12]
 213     m = FRS[12:64]
 214     s = FRS[0]
 215
 216     log ("SINGLE", FRS)
 217     log ("s e m", s.value, e.value, m.value)
 218
 219     #No Denormalization Required (includes Zero / Infinity / NaN)
 220     if e.value > 896 or FRS[1:64].value  == 0:
 221           log("nodenorm", FRS[0:2].value, hex(FRS[5:35].value))
 222           WORD[0:2] = FRS[0:2]
 223           WORD[2:32] = FRS[5:35]
 224
 225     #Denormalization Required
 226     if e.value  >= 874 and e.value <= 896:
 227           sign = FRS[0]
 228           exp = e.value - 1023
 229           frac = selectconcat(SelectableInt(1, 1), FRS[12:64])
 230           log("exp, fract", exp, hex(frac.value))
 231           # denormalize operand
 232           while exp < -126:
 233               frac[0:53] = selectconcat(SelectableInt(0, 1), frac[0:52])
 234               exp = exp + 1
 235           WORD[0] = sign
 236           WORD[1:9] = SelectableInt(0, 8)
 237           WORD[9:32] = frac[1:24]
 238     #else WORD = undefined # return zeros
 239
 240     log ("WORD", WORD)
 241
 242     return WORD
 243
 244 # XXX NOTE: these are very quick hacked functions for utterly basic
 245 # FP support
 246
 247 def fp64toselectable(frt):
 248     """convert FP number to 64 bit SelectableInt
 249     """
 250     b = struct.pack(">d", frt)
 251     val = int.from_bytes(b, byteorder='big', signed=False)
 252     return SelectableInt(val, 64)
 253
 254
 255 def FPADD32(FRA, FRB):
 256     #return FPADD64(FRA, FRB)
 257     #FRA = DOUBLE(SINGLE(FRA))
 258     #FRB = DOUBLE(SINGLE(FRB))
 259     result = float(FRA) + float(FRB)
 260     cvt = fp64toselectable(result)
 261     cvt = DOUBLE(SINGLE(cvt))
 262     log ("FPADD32", FRA, FRB, result, cvt)
 263     return cvt
 264
 265
 266 def FPSUB32(FRA, FRB):
 267     #return FPSUB64(FRA, FRB)
 268     #FRA = DOUBLE(SINGLE(FRA))
 269     #FRB = DOUBLE(SINGLE(FRB))
 270     result = float(FRA) - float(FRB)
 271     cvt = fp64toselectable(result)
 272     cvt = DOUBLE(SINGLE(cvt))
 273     log ("FPSUB32", FRA, FRB, result, cvt)
 274     return cvt
 275
 276
 277 def FPMUL32(FRA, FRB):
 278     #return FPMUL64(FRA, FRB)
 279     #FRA = DOUBLE(SINGLE(FRA))
 280     #FRB = DOUBLE(SINGLE(FRB))
 281     result = float(FRA) * float(FRB)
 282     cvt = fp64toselectable(result)
 283     cvt = DOUBLE(SINGLE(cvt))
 284     log ("FPMUL32", FRA, FRB, result, cvt)
 285     return cvt
 286
 287
 288 def FPDIV32(FRA, FRB):
 289     #return FPDIV64(FRA, FRB)
 290     #FRA = DOUBLE(SINGLE(FRA))
 291     #FRB = DOUBLE(SINGLE(FRB))
 292     result = float(FRA) / float(FRB)
 293     cvt = fp64toselectable(result)
 294     cvt = DOUBLE(SINGLE(cvt))
 295     log ("FPDIV32", FRA, FRB, result, cvt)
 296     return cvt
 297
 298
 299 def FPADD64(FRA, FRB):
 300     result = float(FRA) + float(FRB)
 301     cvt = fp64toselectable(result)
 302     log ("FPADD64", FRA, FRB, result, cvt)
 303     return cvt
 304
 305
 306 def FPSUB64(FRA, FRB):
 307     result = float(FRA) - float(FRB)
 308     cvt = fp64toselectable(result)
 309     log ("FPSUB64", FRA, FRB, result, cvt)
 310     return cvt
 311
 312
 313 def FPMUL64(FRA, FRB):
 314     result = float(FRA) * float(FRB)
 315     cvt = fp64toselectable(result)
 316     log ("FPMUL64", FRA, FRB, result, cvt)
 317     return cvt
 318
 319
 320 def FPDIV64(FRA, FRB):
 321     result = float(FRA) / float(FRB)
 322     cvt = fp64toselectable(result)
 323     log ("FPDIV64", FRA, FRB, result, cvt)
 324     return cvt
 325
 326
 327 # For these tests I tried to find power instructions that would let me
 328 # isolate each of these helper operations. So for instance, when I was
 329 # testing the MASK() function, I chose rlwinm and rldicl because if I
 330 # set the shift equal to 0 and passed in a value of all ones, the
 331 # result I got would be exactly the same as the output of MASK()
 332
 333
 334 class HelperTests(unittest.TestCase):
 335     def test_MASK(self):
 336         # Verified using rlwinm, rldicl, rldicr in qemu
 337         # li 1, -1
 338         # rlwinm reg, 1, 0, 5, 15
 339         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 340         # rlwinm reg, 1, 0, 15, 5
 341         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 342         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 343         # rldicl reg, 1, 0, 37
 344         self.assertHex(MASK(37, 63), 0x7ffffff)
 345         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 346         self.assertHex(MASK(58, 63), 0x3f)
 347         # rldicr reg, 1, 0, 37
 348         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 349         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 350         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 351
 352         # li 2, 5
 353         # slw 1, 1, 2
 354         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 355
 356         self.assertHex(MASK(32, 33), 0xc0000000)
 357         self.assertHex(MASK(32, 32), 0x80000000)
 358         self.assertHex(MASK(33, 33), 0x40000000)
 359
 360     def test_ROTL64(self):
 361         # r1 = 0xdeadbeef12345678
 362         value = 0xdeadbeef12345678
 363
 364         # rldicl reg, 1, 10, 0
 365         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 366         # rldicl reg, 1, 35, 0
 367         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 368         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 369         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 370
 371     def test_ROTL32(self):
 372         # r1 = 0xdeadbeef
 373         value = 0xdeadbeef
 374
 375         # rlwinm reg, 1, 10, 0, 31
 376         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 377         # rlwinm reg, 1, 17, 0, 31
 378         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 379         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 380         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 381
 382     def test_EXTS64(self):
 383         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 384         value_b = SelectableInt(0x73123456, 32)  # r2
 385         value_c = SelectableInt(0x80000000, 32)  # r3
 386
 387         # extswsli reg, 1, 0
 388         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 389         # extswsli reg, 2, 0
 390         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 391         # extswsli reg, 3, 0
 392         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 393
 394     def test_FPADD32(self):
 395         value_a = SelectableInt(0x4014000000000000, 64)  # 5.0
 396         value_b = SelectableInt(0x403B4CCCCCCCCCCD, 64)  # 27.3
 397         result = FPADD32(value_a, value_b)
 398         self.assertHex(0x4040266666666666, result)
 399
 400     def assertHex(self, a, b):
 401         a_val = a
 402         if isinstance(a, SelectableInt):
 403             a_val = a.value
 404         b_val = b
 405         if isinstance(b, SelectableInt):
 406             b_val = b.value
 407         msg = "{:x} != {:x}".format(a_val, b_val)
 408         return self.assertEqual(a, b, msg)
 409
 410
 411 if __name__ == '__main__':
 412     log(SelectableInt.__bases__)
 413     unittest.main()