src/soc/decoder/selectable_int.py

   1 import unittest
   2 from copy import copy
   3
   4
   5 class SelectableInt:
   6     def __init__(self, value, bits):
   7         mask = (1 << bits) - 1
   8         self.value = value & mask
   9         self.bits = bits
  10
  11     def __add__(self, b):
  12         assert b.bits == self.bits
  13         return SelectableInt(self.value + b.value, self.bits)
  14
  15     def __sub__(self, b):
  16         assert b.bits == self.bits
  17         return SelectableInt(self.value - b.value, self.bits)
  18
  19     def __mul__(self, b):
  20         assert b.bits == self.bits
  21         return SelectableInt(self.value * b.value, self.bits)
  22
  23     def __or__(self, b):
  24         assert b.bits == self.bits
  25         return SelectableInt(self.value | b.value, self.bits)
  26
  27     def __and__(self, b):
  28         assert b.bits == self.bits
  29         return SelectableInt(self.value & b.value, self.bits)
  30
  31     def __xor__(self, b):
  32         assert b.bits == self.bits
  33         return SelectableInt(self.value ^ b.value, self.bits)
  34
  35     def __invert__(self):
  36         return SelectableInt(~self.value, self.bits)
  37
  38     def __neg__(self):
  39         return SelectableInt(~self.value + 1, self.bits)
  40
  41     def __getitem__(self, key):
  42         if isinstance(key, int):
  43             assert key < self.bits, "key %d accessing %d" % (key, self.bits)
  44             assert key >= 0
  45             key = self.bits - (key + 1)
  46
  47             value = (self.value >> key) & 1
  48             return SelectableInt(value, 1)
  49         elif isinstance(key, slice):
  50             assert key.step is None or key.step == 1
  51             assert key.start < key.stop
  52             assert key.start >= 0
  53             assert key.stop <= self.bits
  54
  55             stop = self.bits - key.start
  56             start = self.bits - key.stop
  57
  58             bits = stop - start + 1
  59             mask = (1 << bits) - 1
  60             value = (self.value >> start) & mask
  61             return SelectableInt(value, bits)
  62
  63     def __setitem__(self, key, value):
  64         if isinstance(key, int):
  65             assert key < self.bits
  66             assert key >= 0
  67             key = self.bits - (key + 1)
  68             if isinstance(value, SelectableInt):
  69                 assert value.bits == 1
  70                 value = value.value
  71
  72             value = value << key
  73             mask = 1 << key
  74             self.value = (self.value & ~mask) | (value & mask)
  75         elif isinstance(key, slice):
  76             assert key.step is None or key.step == 1
  77             assert key.start < key.stop
  78             assert key.start >= 0
  79             assert key.stop <= self.bits
  80
  81             stop = self.bits - key.start
  82             start = self.bits - key.stop
  83
  84             bits = stop - start + 1
  85             if isinstance(value, SelectableInt):
  86                 assert value.bits == bits, "%d into %d" % (value.bits, bits)
  87                 value = value.value
  88             mask = ((1 << bits) - 1) << start
  89             value = value << start
  90             self.value = (self.value & ~mask) | (value & mask)
  91
  92     def __ge__(self, other):
  93         if isinstance(other, SelectableInt):
  94             assert other.bits == self.bits
  95             other = other.value
  96         if isinstance(other, int):
  97             return other >= self.value
  98         assert False
  99
 100     def __le__(self, other):
 101         if isinstance(other, SelectableInt):
 102             assert other.bits == self.bits
 103             other = other.value
 104         if isinstance(other, int):
 105             return onebit(other <= self.value)
 106         assert False
 107
 108     def __gt__(self, other):
 109         if isinstance(other, SelectableInt):
 110             assert other.bits == self.bits
 111             other = other.value
 112         if isinstance(other, int):
 113             return onebit(other > self.value)
 114         assert False
 115
 116     def __lt__(self, other):
 117         if isinstance(other, SelectableInt):
 118             assert other.bits == self.bits
 119             other = other.value
 120         if isinstance(other, int):
 121             return onebit(other < self.value)
 122         assert False
 123
 124     def __eq__(self, other):
 125         if isinstance(other, SelectableInt):
 126             assert other.bits == self.bits
 127             other = other.value
 128         if isinstance(other, int):
 129             return onebit(other == self.value)
 130         assert False
 131
 132     def __repr__(self):
 133         return "SelectableInt(value={:x}, bits={})".format(self.value,
 134                                                            self.bits)
 135
 136 def onebit(bit):
 137     return SelectableInt(1 if bit else 0, 1)
 138
 139 def selectltu(lhs, rhs):
 140     """ less-than (unsigned)
 141     """
 142     if isinstance(rhs, SelectableInt):
 143         rhs = rhs.value
 144     return onebit(lhs.value < rhs)
 145
 146 def selectgtu(lhs, rhs):
 147     """ greater-than (unsigned)
 148     """
 149     if isinstance(rhs, SelectableInt):
 150         rhs = rhs.value
 151     return onebit(lhs.value > rhs)
 152
 153
 154 # XXX this probably isn't needed...
 155 def selectassign(lhs, idx, rhs):
 156     if isinstance(idx, tuple):
 157         if len(idx) == 2:
 158             lower, upper = idx
 159             step = None
 160         else:
 161             lower, upper, step = idx
 162         toidx = range(lower, upper, step)
 163         fromidx = range(0, upper-lower, step) # XXX eurgh...
 164     else:
 165         toidx = [idx]
 166         fromidx = [0]
 167     for t, f in zip(toidx, fromidx):
 168         lhs[t] = rhs[f]
 169
 170
 171 def selectconcat(*args):
 172     res = copy(args[0])
 173     for i in args[1:]:
 174         assert isinstance(i, SelectableInt), "can only concat SIs, sorry"
 175         res.bits += i.bits
 176         res.value = (res.value << i.bits) | i.value
 177     return res
 178
 179
 180 class SelectableIntTestCase(unittest.TestCase):
 181     def test_arith(self):
 182         a = SelectableInt(5, 8)
 183         b = SelectableInt(9, 8)
 184         c = a + b
 185         d = a - b
 186         e = a * b
 187         f = -a
 188         self.assertEqual(c.value, a.value + b.value)
 189         self.assertEqual(d.value, (a.value - b.value) & 0xFF)
 190         self.assertEqual(e.value, (a.value * b.value) & 0xFF)
 191         self.assertEqual(f.value, (-a.value) & 0xFF)
 192         self.assertEqual(c.bits, a.bits)
 193         self.assertEqual(d.bits, a.bits)
 194         self.assertEqual(e.bits, a.bits)
 195
 196     def test_logic(self):
 197         a = SelectableInt(0x0F, 8)
 198         b = SelectableInt(0xA5, 8)
 199         c = a & b
 200         d = a | b
 201         e = a ^ b
 202         f = ~a
 203         self.assertEqual(c.value, a.value & b.value)
 204         self.assertEqual(d.value, a.value | b.value)
 205         self.assertEqual(e.value, a.value ^ b.value)
 206         self.assertEqual(f.value, 0xF0)
 207
 208     def test_get(self):
 209         a = SelectableInt(0xa2, 8)
 210         # These should be big endian
 211         self.assertEqual(a[7], 0)
 212         self.assertEqual(a[0:4], 10)
 213         self.assertEqual(a[4:8], 2)
 214
 215     def test_set(self):
 216         a = SelectableInt(0x5, 8)
 217         a[7] = SelectableInt(0, 1)
 218         self.assertEqual(a, 4)
 219         a[4:8] = 9
 220         self.assertEqual(a, 9)
 221         a[0:4] = 3
 222         self.assertEqual(a, 0x39)
 223         a[0:4] = a[4:8]
 224         self.assertEqual(a, 0x199)
 225
 226 if __name__ == "__main__":
 227     unittest.main()