src/soc/decoder/helpers.py

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