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 from soc.decoder.selectable_int import check_extsign
   8
   9 trunc_div = floordiv
  10 trunc_rem = mod
  11 DIVS = trunc_divs
  12 MODS = trunc_rems
  13
  14 """
  15 Links:
  16 * https://bugs.libre-soc.org/show_bug.cgi?id=324 - add trunc_div and trunc_rem
  17 """
  18
  19
  20 def exts(value, bits):
  21     sign = 1 << (bits - 1)
  22     return (value & (sign - 1)) - (value & sign)
  23
  24
  25 def EXTS(value):
  26     """ extends sign bit out from current MSB to all 256 bits
  27     """
  28     assert isinstance(value, SelectableInt)
  29     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  30
  31
  32 def EXTS64(value):
  33     """ extends sign bit out from current MSB to 64 bits
  34     """
  35     assert isinstance(value, SelectableInt)
  36     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  37
  38
  39 # signed version of MUL
  40 def MULS(a, b):
  41     if isinstance(b, int):
  42         b = SelectableInt(b, self.bits)
  43     b = check_extsign(a, b)
  44     a_s = a.value & (1 << (a.bits-1)) != 0
  45     b_s = b.value & (1 << (b.bits-1)) != 0
  46     result = abs(a) * abs(b)
  47     print("MULS", result, a_s, b_s)
  48     if a_s == b_s:
  49         return result
  50     return -result
  51
  52
  53 # XXX should this explicitly extend from 32 to 64?
  54 def EXTZ64(value):
  55     if isinstance(value, SelectableInt):
  56         value = value.value
  57     return SelectableInt(value & ((1 << 32)-1), 64)
  58
  59
  60 def rotl(value, bits, wordlen):
  61     if isinstance(bits, SelectableInt):
  62         bits = bits.value
  63     mask = (1 << wordlen) - 1
  64     bits = bits & (wordlen - 1)
  65     return ((value << bits) | (value >> (wordlen-bits))) & mask
  66
  67
  68 def ROTL64(value, bits):
  69     return rotl(value, bits, 64)
  70
  71
  72 def ROTL32(value, bits):
  73     if isinstance(value, SelectableInt):
  74         value = SelectableInt(value.value, 64)
  75     return rotl(value | (value << 32), bits, 64)
  76
  77
  78 def MASK(x, y):
  79     if isinstance(x, SelectableInt):
  80         x = x.value
  81     if isinstance(y, SelectableInt):
  82         y = y.value
  83     if x < y:
  84         x = 64-x
  85         y = 63-y
  86         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  87         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
  88     elif x == y:
  89         return 1 << (63-x)
  90     else:
  91         x = 64-x
  92         y = 63-y
  93         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  94         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
  95     return mask_a ^ mask_b
  96
  97
  98 def ne(a, b):
  99     return onebit(a != b)
 100
 101
 102 def eq(a, b):
 103     return onebit(a == b)
 104
 105
 106 def gt(a, b):
 107     return onebit(a > b)
 108
 109
 110 def ge(a, b):
 111     return onebit(a >= b)
 112
 113
 114 def lt(a, b):
 115     return onebit(a < b)
 116
 117
 118 def le(a, b):
 119     return onebit(a <= b)
 120
 121
 122 def length(a):
 123     return len(a)
 124
 125 # For these tests I tried to find power instructions that would let me
 126 # isolate each of these helper operations. So for instance, when I was
 127 # testing the MASK() function, I chose rlwinm and rldicl because if I
 128 # set the shift equal to 0 and passed in a value of all ones, the
 129 # result I got would be exactly the same as the output of MASK()
 130
 131
 132 class HelperTests(unittest.TestCase):
 133     def test_MASK(self):
 134         # Verified using rlwinm, rldicl, rldicr in qemu
 135         # li 1, -1
 136         # rlwinm reg, 1, 0, 5, 15
 137         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 138         # rlwinm reg, 1, 0, 15, 5
 139         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 140         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 141         # rldicl reg, 1, 0, 37
 142         self.assertHex(MASK(37, 63), 0x7ffffff)
 143         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 144         self.assertHex(MASK(58, 63), 0x3f)
 145         # rldicr reg, 1, 0, 37
 146         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 147         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 148         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 149
 150         # li 2, 5
 151         # slw 1, 1, 2
 152         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 153
 154         self.assertHex(MASK(32, 33), 0xc0000000)
 155         self.assertHex(MASK(32, 32), 0x80000000)
 156         self.assertHex(MASK(33, 33), 0x40000000)
 157
 158     def test_ROTL64(self):
 159         # r1 = 0xdeadbeef12345678
 160         value = 0xdeadbeef12345678
 161
 162         # rldicl reg, 1, 10, 0
 163         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 164         # rldicl reg, 1, 35, 0
 165         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 166         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 167         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 168
 169     def test_ROTL32(self):
 170         # r1 = 0xdeadbeef
 171         value = 0xdeadbeef
 172
 173         # rlwinm reg, 1, 10, 0, 31
 174         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 175         # rlwinm reg, 1, 17, 0, 31
 176         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 177         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 178         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 179
 180     def test_EXTS64(self):
 181         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 182         value_b = SelectableInt(0x73123456, 32)  # r2
 183         value_c = SelectableInt(0x80000000, 32)  # r3
 184
 185         # extswsli reg, 1, 0
 186         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 187         # extswsli reg, 2, 0
 188         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 189         # extswsli reg, 3, 0
 190         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 191
 192     def assertHex(self, a, b):
 193         a_val = a
 194         if isinstance(a, SelectableInt):
 195             a_val = a.value
 196         b_val = b
 197         if isinstance(b, SelectableInt):
 198             b_val = b.value
 199         msg = "{:x} != {:x}".format(a_val, b_val)
 200         return self.assertEqual(a, b, msg)
 201
 202
 203 if __name__ == '__main__':
 204     print(SelectableInt.__bases__)
 205     unittest.main()