src/soc/decoder/helpers.py

   1 import unittest
   2 from soc.decoder.selectable_int import SelectableInt
   3
   4 """
   5 Links:
   6 * https://bugs.libre-soc.org/show_bug.cgi?id=324 - add trunc_div and trunc_rem
   7 """
   8
   9 def exts(value, bits):
  10     sign = 1 << (bits - 1)
  11     return (value & (sign - 1)) - (value & sign)
  12
  13 def trunc_div(n, d):
  14     f = getattr(n, "trunc_div", None)
  15     if f is not None:
  16         return f(d)
  17     fr = getattr(d, "rtrunc_div", None)
  18     if fr is not None:
  19         return fr(n)
  20     abs_n = abs(n)
  21     abs_d = abs(d)
  22     abs_q = n // d
  23     if (n < 0) == (d < 0):
  24         return abs_q
  25     return -abs_q
  26
  27 def trunc_rem(n, d):
  28     f = getattr(n, "trunc_rem", None)
  29     if f is not None:
  30         return f(d)
  31     fr = getattr(d, "rtrunc_rem", None)
  32     if fr is not None:
  33         return fr(n)
  34     return n - d * trunc_div(n, d)
  35
  36
  37 def EXTS(value):
  38     """ extends sign bit out from current MSB to all 256 bits
  39     """
  40     assert isinstance(value, SelectableInt)
  41     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  42
  43 def EXTS64(value):
  44     """ extends sign bit out from current MSB to 64 bits
  45     """
  46     assert isinstance(value, SelectableInt)
  47     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  48
  49
  50 # XXX should this explicitly extend from 32 to 64?
  51 def EXTZ64(value):
  52     if isinstance(value, SelectableInt):
  53         value = value.value
  54     return SelectableInt(value & ((1<<32)-1), 64)
  55
  56
  57 def rotl(value, bits, wordlen):
  58     if isinstance(bits, SelectableInt):
  59         bits = bits.value
  60     mask = (1 << wordlen) - 1
  61     bits = bits & (wordlen - 1)
  62     return ((value << bits) | (value >> (wordlen-bits))) & mask
  63
  64
  65 def ROTL64(value, bits):
  66     return rotl(value, bits, 64)
  67
  68
  69 def ROTL32(value, bits):
  70     if isinstance(value, SelectableInt):
  71         value = SelectableInt(value.value, 64)
  72     return rotl(value | (value << 32), bits, 64)
  73
  74
  75 def MASK(x, y):
  76     if isinstance(x, SelectableInt):
  77         x = x.value
  78     if isinstance(y, SelectableInt):
  79         y = y.value
  80     if x < y:
  81         x = 64-x
  82         y = 63-y
  83         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  84         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
  85     elif x == y:
  86         return 1 << (63-x)
  87     else:
  88         x = 64-x
  89         y = 63-y
  90         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  91         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
  92     return mask_a ^ mask_b
  93
  94 def ne(a, b):
  95     return SelectableInt((a != b), bits=1)
  96
  97 def eq(a, b):
  98     return SelectableInt((a == b), bits=1)
  99
 100 def gt(a, b):
 101     return SelectableInt((a > b), bits=1)
 102
 103 def ge(a, b):
 104     return SelectableInt((a >= b), bits=1)
 105
 106 def lt(a, b):
 107     return SelectableInt((a < b), bits=1)
 108
 109 def le(a, b):
 110     return SelectableInt((a <= b), bits=1)
 111
 112 def length(a):
 113     return len(a)
 114
 115 # For these tests I tried to find power instructions that would let me
 116 # isolate each of these helper operations. So for instance, when I was
 117 # testing the MASK() function, I chose rlwinm and rldicl because if I
 118 # set the shift equal to 0 and passed in a value of all ones, the
 119 # result I got would be exactly the same as the output of MASK()
 120
 121 class HelperTests(unittest.TestCase):
 122     def test_MASK(self):
 123         # Verified using rlwinm, rldicl, rldicr in qemu
 124         # li 1, -1
 125         # rlwinm reg, 1, 0, 5, 15
 126         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 127         # rlwinm reg, 1, 0, 15, 5
 128         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 129         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 130         # rldicl reg, 1, 0, 37
 131         self.assertHex(MASK(37, 63), 0x7ffffff)
 132         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 133         self.assertHex(MASK(58, 63), 0x3f)
 134         # rldicr reg, 1, 0, 37
 135         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 136         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 137         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 138
 139         # li 2, 5
 140         # slw 1, 1, 2
 141         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 142
 143         self.assertHex(MASK(32, 33), 0xc0000000)
 144         self.assertHex(MASK(32, 32), 0x80000000)
 145         self.assertHex(MASK(33, 33), 0x40000000)
 146
 147     def test_ROTL64(self):
 148         # r1 = 0xdeadbeef12345678
 149         value = 0xdeadbeef12345678
 150
 151         # rldicl reg, 1, 10, 0
 152         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 153         # rldicl reg, 1, 35, 0
 154         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 155         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 156         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 157
 158     def test_ROTL32(self):
 159         # r1 = 0xdeadbeef
 160         value = 0xdeadbeef
 161
 162         # rlwinm reg, 1, 10, 0, 31
 163         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 164         # rlwinm reg, 1, 17, 0, 31
 165         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 166         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 167         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 168
 169     def test_EXTS64(self):
 170         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 171         value_b = SelectableInt(0x73123456, 32)  # r2
 172         value_c = SelectableInt(0x80000000, 32)  # r3
 173
 174         # extswsli reg, 1, 0
 175         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 176         # extswsli reg, 2, 0
 177         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 178         # extswsli reg, 3, 0
 179         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 180
 181     def assertHex(self, a, b):
 182         a_val = a
 183         if isinstance(a, SelectableInt):
 184             a_val = a.value
 185         b_val = b
 186         if isinstance(b, SelectableInt):
 187             b_val = b.value
 188         msg = "{:x} != {:x}".format(a_val, b_val)
 189         return self.assertEqual(a, b, msg)
 190
 191
 192 if __name__ == '__main__':
 193     print (SelectableInt.__bases__)
 194     unittest.main()