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 __div__(self, b):
  24         assert b.bits == self.bits
  25         return SelectableInt(self.value / b.value, self.bits)
  26
  27     def __mod__(self, b):
  28         assert b.bits == self.bits
  29         return SelectableInt(self.value % b.value, self.bits)
  30
  31     def __or__(self, b):
  32         assert b.bits == self.bits
  33         return SelectableInt(self.value | b.value, self.bits)
  34
  35     def __and__(self, b):
  36         assert b.bits == self.bits
  37         return SelectableInt(self.value & b.value, self.bits)
  38
  39     def __xor__(self, b):
  40         assert b.bits == self.bits
  41         return SelectableInt(self.value ^ b.value, self.bits)
  42
  43     def __invert__(self):
  44         return SelectableInt(~self.value, self.bits)
  45
  46     def __neg__(self):
  47         return SelectableInt(~self.value + 1, self.bits)
  48
  49     def __getitem__(self, key):
  50         if isinstance(key, int):
  51             assert key < self.bits, "key %d accessing %d" % (key, self.bits)
  52             assert key >= 0
  53             key = self.bits - (key + 1)
  54
  55             value = (self.value >> key) & 1
  56             return SelectableInt(value, 1)
  57         elif isinstance(key, slice):
  58             assert key.step is None or key.step == 1
  59             assert key.start < key.stop
  60             assert key.start >= 0
  61             assert key.stop <= self.bits
  62
  63             stop = self.bits - key.start
  64             start = self.bits - key.stop
  65
  66             bits = stop - start + 1
  67             mask = (1 << bits) - 1
  68             value = (self.value >> start) & mask
  69             return SelectableInt(value, bits)
  70
  71     def __setitem__(self, key, value):
  72         if isinstance(key, int):
  73             assert key < self.bits
  74             assert key >= 0
  75             key = self.bits - (key + 1)
  76             if isinstance(value, SelectableInt):
  77                 assert value.bits == 1
  78                 value = value.value
  79
  80             value = value << key
  81             mask = 1 << key
  82             self.value = (self.value & ~mask) | (value & mask)
  83         elif isinstance(key, slice):
  84             assert key.step is None or key.step == 1
  85             assert key.start < key.stop
  86             assert key.start >= 0
  87             assert key.stop <= self.bits
  88
  89             stop = self.bits - key.start
  90             start = self.bits - key.stop
  91
  92             bits = stop - start + 1
  93             if isinstance(value, SelectableInt):
  94                 assert value.bits == bits, "%d into %d" % (value.bits, bits)
  95                 value = value.value
  96             mask = ((1 << bits) - 1) << start
  97             value = value << start
  98             self.value = (self.value & ~mask) | (value & mask)
  99
 100     def __ge__(self, other):
 101         if isinstance(other, SelectableInt):
 102             assert other.bits == self.bits
 103             other = other.value
 104         if isinstance(other, int):
 105             return other >= self.value
 106         assert False
 107
 108     def __le__(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 __gt__(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 __lt__(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 __eq__(self, other):
 133         if isinstance(other, SelectableInt):
 134             assert other.bits == self.bits
 135             other = other.value
 136         if isinstance(other, int):
 137             return onebit(other == self.value)
 138         assert False
 139
 140     def __bool__(self):
 141         return self.value != 0
 142
 143     def __repr__(self):
 144         return "SelectableInt(value={:x}, bits={})".format(self.value,
 145                                                            self.bits)
 146
 147 def onebit(bit):
 148     return SelectableInt(1 if bit else 0, 1)
 149
 150 def selectltu(lhs, rhs):
 151     """ less-than (unsigned)
 152     """
 153     if isinstance(rhs, SelectableInt):
 154         rhs = rhs.value
 155     return onebit(lhs.value < rhs)
 156
 157 def selectgtu(lhs, rhs):
 158     """ greater-than (unsigned)
 159     """
 160     if isinstance(rhs, SelectableInt):
 161         rhs = rhs.value
 162     return onebit(lhs.value > rhs)
 163
 164
 165 # XXX this probably isn't needed...
 166 def selectassign(lhs, idx, rhs):
 167     if isinstance(idx, tuple):
 168         if len(idx) == 2:
 169             lower, upper = idx
 170             step = None
 171         else:
 172             lower, upper, step = idx
 173         toidx = range(lower, upper, step)
 174         fromidx = range(0, upper-lower, step) # XXX eurgh...
 175     else:
 176         toidx = [idx]
 177         fromidx = [0]
 178     for t, f in zip(toidx, fromidx):
 179         lhs[t] = rhs[f]
 180
 181
 182 def selectconcat(*args):
 183     res = copy(args[0])
 184     for i in args[1:]:
 185         assert isinstance(i, SelectableInt), "can only concat SIs, sorry"
 186         res.bits += i.bits
 187         res.value = (res.value << i.bits) | i.value
 188     return res
 189
 190
 191 class SelectableIntTestCase(unittest.TestCase):
 192     def test_arith(self):
 193         a = SelectableInt(5, 8)
 194         b = SelectableInt(9, 8)
 195         c = a + b
 196         d = a - b
 197         e = a * b
 198         f = -a
 199         self.assertEqual(c.value, a.value + b.value)
 200         self.assertEqual(d.value, (a.value - b.value) & 0xFF)
 201         self.assertEqual(e.value, (a.value * b.value) & 0xFF)
 202         self.assertEqual(f.value, (-a.value) & 0xFF)
 203         self.assertEqual(c.bits, a.bits)
 204         self.assertEqual(d.bits, a.bits)
 205         self.assertEqual(e.bits, a.bits)
 206
 207     def test_logic(self):
 208         a = SelectableInt(0x0F, 8)
 209         b = SelectableInt(0xA5, 8)
 210         c = a & b
 211         d = a | b
 212         e = a ^ b
 213         f = ~a
 214         self.assertEqual(c.value, a.value & b.value)
 215         self.assertEqual(d.value, a.value | b.value)
 216         self.assertEqual(e.value, a.value ^ b.value)
 217         self.assertEqual(f.value, 0xF0)
 218
 219     def test_get(self):
 220         a = SelectableInt(0xa2, 8)
 221         # These should be big endian
 222         self.assertEqual(a[7], 0)
 223         self.assertEqual(a[0:4], 10)
 224         self.assertEqual(a[4:8], 2)
 225
 226     def test_set(self):
 227         a = SelectableInt(0x5, 8)
 228         a[7] = SelectableInt(0, 1)
 229         self.assertEqual(a, 4)
 230         a[4:8] = 9
 231         self.assertEqual(a, 9)
 232         a[0:4] = 3
 233         self.assertEqual(a, 0x39)
 234         a[0:4] = a[4:8]
 235         self.assertEqual(a, 0x199)
 236
 237 if __name__ == "__main__":
 238     unittest.main()