src/soc/decoder/helpers.py

   1 import unittest
   2 from soc.decoder.selectable_int import SelectableInt, onebit
   3 from nmutil.divmod import trunc_divs, trunc_rems
   4 from operator import floordiv, mod
   5 from soc.decoder.selectable_int import selectltu as ltu
   6 from soc.decoder.selectable_int import selectgtu as gtu
   7
   8 trunc_div = floordiv
   9 trunc_rem = mod
  10 DIVS = trunc_divs
  11 MODS = trunc_rems
  12
  13 """
  14 Links:
  15 * https://bugs.libre-soc.org/show_bug.cgi?id=324 - add trunc_div and trunc_rem
  16 """
  17
  18 def exts(value, bits):
  19     sign = 1 << (bits - 1)
  20     return (value & (sign - 1)) - (value & sign)
  21
  22
  23 def EXTS(value):
  24     """ extends sign bit out from current MSB to all 256 bits
  25     """
  26     assert isinstance(value, SelectableInt)
  27     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  28
  29 def EXTS64(value):
  30     """ extends sign bit out from current MSB to 64 bits
  31     """
  32     assert isinstance(value, SelectableInt)
  33     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  34
  35
  36 # signed version of MUL
  37 def MULS(a, b):
  38     a_s = a.value & (1<<(a.bits-1)) != 0
  39     b_s = b.value & (1<<(b.bits-1)) != 0
  40     result = abs(a) * abs(b)
  41     print ("MULS", result, a_s, b_s)
  42     if a_s == b_s:
  43         return result
  44     return -result
  45
  46
  47 # XXX should this explicitly extend from 32 to 64?
  48 def EXTZ64(value):
  49     if isinstance(value, SelectableInt):
  50         value = value.value
  51     return SelectableInt(value & ((1<<32)-1), 64)
  52
  53
  54 def rotl(value, bits, wordlen):
  55     if isinstance(bits, SelectableInt):
  56         bits = bits.value
  57     mask = (1 << wordlen) - 1
  58     bits = bits & (wordlen - 1)
  59     return ((value << bits) | (value >> (wordlen-bits))) & mask
  60
  61
  62 def ROTL64(value, bits):
  63     return rotl(value, bits, 64)
  64
  65
  66 def ROTL32(value, bits):
  67     if isinstance(value, SelectableInt):
  68         value = SelectableInt(value.value, 64)
  69     return rotl(value | (value << 32), bits, 64)
  70
  71
  72 def MASK(x, y):
  73     if isinstance(x, SelectableInt):
  74         x = x.value
  75     if isinstance(y, SelectableInt):
  76         y = y.value
  77     if x < y:
  78         x = 64-x
  79         y = 63-y
  80         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  81         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
  82     elif x == y:
  83         return 1 << (63-x)
  84     else:
  85         x = 64-x
  86         y = 63-y
  87         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  88         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
  89     return mask_a ^ mask_b
  90
  91 def ne(a, b):
  92     return onebit(a != b)
  93
  94 def eq(a, b):
  95     return onebit(a == b)
  96
  97 def gt(a, b):
  98     return onebit(a > b)
  99
 100 def ge(a, b):
 101     return onebit(a >= b)
 102
 103 def lt(a, b):
 104     return onebit(a < b)
 105
 106 def le(a, b):
 107     return onebit(a <= b)
 108
 109 def length(a):
 110     return len(a)
 111
 112 # For these tests I tried to find power instructions that would let me
 113 # isolate each of these helper operations. So for instance, when I was
 114 # testing the MASK() function, I chose rlwinm and rldicl because if I
 115 # set the shift equal to 0 and passed in a value of all ones, the
 116 # result I got would be exactly the same as the output of MASK()
 117
 118 class HelperTests(unittest.TestCase):
 119     def test_MASK(self):
 120         # Verified using rlwinm, rldicl, rldicr in qemu
 121         # li 1, -1
 122         # rlwinm reg, 1, 0, 5, 15
 123         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 124         # rlwinm reg, 1, 0, 15, 5
 125         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 126         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 127         # rldicl reg, 1, 0, 37
 128         self.assertHex(MASK(37, 63), 0x7ffffff)
 129         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 130         self.assertHex(MASK(58, 63), 0x3f)
 131         # rldicr reg, 1, 0, 37
 132         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 133         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 134         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 135
 136         # li 2, 5
 137         # slw 1, 1, 2
 138         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 139
 140         self.assertHex(MASK(32, 33), 0xc0000000)
 141         self.assertHex(MASK(32, 32), 0x80000000)
 142         self.assertHex(MASK(33, 33), 0x40000000)
 143
 144     def test_ROTL64(self):
 145         # r1 = 0xdeadbeef12345678
 146         value = 0xdeadbeef12345678
 147
 148         # rldicl reg, 1, 10, 0
 149         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 150         # rldicl reg, 1, 35, 0
 151         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 152         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 153         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 154
 155     def test_ROTL32(self):
 156         # r1 = 0xdeadbeef
 157         value = 0xdeadbeef
 158
 159         # rlwinm reg, 1, 10, 0, 31
 160         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 161         # rlwinm reg, 1, 17, 0, 31
 162         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 163         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 164         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 165
 166     def test_EXTS64(self):
 167         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 168         value_b = SelectableInt(0x73123456, 32)  # r2
 169         value_c = SelectableInt(0x80000000, 32)  # r3
 170
 171         # extswsli reg, 1, 0
 172         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 173         # extswsli reg, 2, 0
 174         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 175         # extswsli reg, 3, 0
 176         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 177
 178     def assertHex(self, a, b):
 179         a_val = a
 180         if isinstance(a, SelectableInt):
 181             a_val = a.value
 182         b_val = b
 183         if isinstance(b, SelectableInt):
 184             b_val = b.value
 185         msg = "{:x} != {:x}".format(a_val, b_val)
 186         return self.assertEqual(a, b, msg)
 187
 188
 189 if __name__ == '__main__':
 190     print (SelectableInt.__bases__)
 191     unittest.main()