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
  19 def exts(value, bits):
  20     sign = 1 << (bits - 1)
  21     return (value & (sign - 1)) - (value & sign)
  22
  23
  24 def EXTS(value):
  25     """ extends sign bit out from current MSB to all 256 bits
  26     """
  27     assert isinstance(value, SelectableInt)
  28     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  29
  30
  31 def EXTS64(value):
  32     """ extends sign bit out from current MSB to 64 bits
  33     """
  34     assert isinstance(value, SelectableInt)
  35     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  36
  37
  38 # signed version of MUL
  39 def MULS(a, b):
  40     a_s = a.value & (1 << (a.bits-1)) != 0
  41     b_s = b.value & (1 << (b.bits-1)) != 0
  42     result = abs(a) * abs(b)
  43     print("MULS", result, a_s, b_s)
  44     if a_s == b_s:
  45         return result
  46     return -result
  47
  48
  49 # XXX should this explicitly extend from 32 to 64?
  50 def EXTZ64(value):
  51     if isinstance(value, SelectableInt):
  52         value = value.value
  53     return SelectableInt(value & ((1 << 32)-1), 64)
  54
  55
  56 def rotl(value, bits, wordlen):
  57     if isinstance(bits, SelectableInt):
  58         bits = bits.value
  59     mask = (1 << wordlen) - 1
  60     bits = bits & (wordlen - 1)
  61     return ((value << bits) | (value >> (wordlen-bits))) & mask
  62
  63
  64 def ROTL64(value, bits):
  65     return rotl(value, bits, 64)
  66
  67
  68 def ROTL32(value, bits):
  69     if isinstance(value, SelectableInt):
  70         value = SelectableInt(value.value, 64)
  71     return rotl(value | (value << 32), bits, 64)
  72
  73
  74 def MASK(x, y):
  75     if isinstance(x, SelectableInt):
  76         x = x.value
  77     if isinstance(y, SelectableInt):
  78         y = y.value
  79     if x < y:
  80         x = 64-x
  81         y = 63-y
  82         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  83         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
  84     elif x == y:
  85         return 1 << (63-x)
  86     else:
  87         x = 64-x
  88         y = 63-y
  89         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  90         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
  91     return mask_a ^ mask_b
  92
  93
  94 def ne(a, b):
  95     return onebit(a != b)
  96
  97
  98 def eq(a, b):
  99     return onebit(a == b)
 100
 101
 102 def gt(a, b):
 103     return onebit(a > b)
 104
 105
 106 def ge(a, b):
 107     return onebit(a >= b)
 108
 109
 110 def lt(a, b):
 111     return onebit(a < b)
 112
 113
 114 def le(a, b):
 115     return onebit(a <= b)
 116
 117
 118 def length(a):
 119     return len(a)
 120
 121 # For these tests I tried to find power instructions that would let me
 122 # isolate each of these helper operations. So for instance, when I was
 123 # testing the MASK() function, I chose rlwinm and rldicl because if I
 124 # set the shift equal to 0 and passed in a value of all ones, the
 125 # result I got would be exactly the same as the output of MASK()
 126
 127
 128 class HelperTests(unittest.TestCase):
 129     def test_MASK(self):
 130         # Verified using rlwinm, rldicl, rldicr in qemu
 131         # li 1, -1
 132         # rlwinm reg, 1, 0, 5, 15
 133         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 134         # rlwinm reg, 1, 0, 15, 5
 135         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 136         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 137         # rldicl reg, 1, 0, 37
 138         self.assertHex(MASK(37, 63), 0x7ffffff)
 139         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 140         self.assertHex(MASK(58, 63), 0x3f)
 141         # rldicr reg, 1, 0, 37
 142         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 143         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 144         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 145
 146         # li 2, 5
 147         # slw 1, 1, 2
 148         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 149
 150         self.assertHex(MASK(32, 33), 0xc0000000)
 151         self.assertHex(MASK(32, 32), 0x80000000)
 152         self.assertHex(MASK(33, 33), 0x40000000)
 153
 154     def test_ROTL64(self):
 155         # r1 = 0xdeadbeef12345678
 156         value = 0xdeadbeef12345678
 157
 158         # rldicl reg, 1, 10, 0
 159         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 160         # rldicl reg, 1, 35, 0
 161         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 162         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 163         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 164
 165     def test_ROTL32(self):
 166         # r1 = 0xdeadbeef
 167         value = 0xdeadbeef
 168
 169         # rlwinm reg, 1, 10, 0, 31
 170         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 171         # rlwinm reg, 1, 17, 0, 31
 172         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 173         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 174         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 175
 176     def test_EXTS64(self):
 177         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 178         value_b = SelectableInt(0x73123456, 32)  # r2
 179         value_c = SelectableInt(0x80000000, 32)  # r3
 180
 181         # extswsli reg, 1, 0
 182         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 183         # extswsli reg, 2, 0
 184         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 185         # extswsli reg, 3, 0
 186         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 187
 188     def assertHex(self, a, b):
 189         a_val = a
 190         if isinstance(a, SelectableInt):
 191             a_val = a.value
 192         b_val = b
 193         if isinstance(b, SelectableInt):
 194             b_val = b.value
 195         msg = "{:x} != {:x}".format(a_val, b_val)
 196         return self.assertEqual(a, b, msg)
 197
 198
 199 if __name__ == '__main__':
 200     print(SelectableInt.__bases__)
 201     unittest.main()