src/soc/decoder/helpers.py

   1 import unittest
   2 from soc.decoder.selectable_int import SelectableInt
   3 from nmutil.divmod import trunc_div, trunc_rem
   4
   5 """
   6 Links:
   7 * https://bugs.libre-soc.org/show_bug.cgi?id=324 - add trunc_div and trunc_rem
   8 """
   9
  10 def exts(value, bits):
  11     sign = 1 << (bits - 1)
  12     return (value & (sign - 1)) - (value & sign)
  13
  14
  15 def EXTS(value):
  16     """ extends sign bit out from current MSB to all 256 bits
  17     """
  18     assert isinstance(value, SelectableInt)
  19     return SelectableInt(exts(value.value, value.bits) & ((1 << 256)-1), 256)
  20
  21 def EXTS64(value):
  22     """ extends sign bit out from current MSB to 64 bits
  23     """
  24     assert isinstance(value, SelectableInt)
  25     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
  26
  27
  28 # XXX should this explicitly extend from 32 to 64?
  29 def EXTZ64(value):
  30     if isinstance(value, SelectableInt):
  31         value = value.value
  32     return SelectableInt(value & ((1<<32)-1), 64)
  33
  34
  35 def rotl(value, bits, wordlen):
  36     if isinstance(bits, SelectableInt):
  37         bits = bits.value
  38     mask = (1 << wordlen) - 1
  39     bits = bits & (wordlen - 1)
  40     return ((value << bits) | (value >> (wordlen-bits))) & mask
  41
  42
  43 def ROTL64(value, bits):
  44     return rotl(value, bits, 64)
  45
  46
  47 def ROTL32(value, bits):
  48     if isinstance(value, SelectableInt):
  49         value = SelectableInt(value.value, 64)
  50     return rotl(value | (value << 32), bits, 64)
  51
  52
  53 def MASK(x, y):
  54     if isinstance(x, SelectableInt):
  55         x = x.value
  56     if isinstance(y, SelectableInt):
  57         y = y.value
  58     if x < y:
  59         x = 64-x
  60         y = 63-y
  61         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  62         mask_b = ((1 << y) - 1) & ((1 << 64) - 1)
  63     elif x == y:
  64         return 1 << (63-x)
  65     else:
  66         x = 64-x
  67         y = 63-y
  68         mask_a = ((1 << x) - 1) & ((1 << 64) - 1)
  69         mask_b = (~((1 << y) - 1)) & ((1 << 64) - 1)
  70     return mask_a ^ mask_b
  71
  72 def ne(a, b):
  73     return SelectableInt((a != b), bits=1)
  74
  75 def eq(a, b):
  76     return SelectableInt((a == b), bits=1)
  77
  78 def gt(a, b):
  79     return SelectableInt((a > b), bits=1)
  80
  81 def ge(a, b):
  82     return SelectableInt((a >= b), bits=1)
  83
  84 def lt(a, b):
  85     return SelectableInt((a < b), bits=1)
  86
  87 def le(a, b):
  88     return SelectableInt((a <= b), bits=1)
  89
  90 def length(a):
  91     return len(a)
  92
  93 # For these tests I tried to find power instructions that would let me
  94 # isolate each of these helper operations. So for instance, when I was
  95 # testing the MASK() function, I chose rlwinm and rldicl because if I
  96 # set the shift equal to 0 and passed in a value of all ones, the
  97 # result I got would be exactly the same as the output of MASK()
  98
  99 class HelperTests(unittest.TestCase):
 100     def test_MASK(self):
 101         # Verified using rlwinm, rldicl, rldicr in qemu
 102         # li 1, -1
 103         # rlwinm reg, 1, 0, 5, 15
 104         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
 105         # rlwinm reg, 1, 0, 15, 5
 106         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
 107         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
 108         # rldicl reg, 1, 0, 37
 109         self.assertHex(MASK(37, 63), 0x7ffffff)
 110         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
 111         self.assertHex(MASK(58, 63), 0x3f)
 112         # rldicr reg, 1, 0, 37
 113         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
 114         self.assertHex(MASK(0, 10), 0xffe0000000000000)
 115         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
 116
 117         # li 2, 5
 118         # slw 1, 1, 2
 119         self.assertHex(MASK(32, 63-5), 0xffffffe0)
 120
 121         self.assertHex(MASK(32, 33), 0xc0000000)
 122         self.assertHex(MASK(32, 32), 0x80000000)
 123         self.assertHex(MASK(33, 33), 0x40000000)
 124
 125     def test_ROTL64(self):
 126         # r1 = 0xdeadbeef12345678
 127         value = 0xdeadbeef12345678
 128
 129         # rldicl reg, 1, 10, 0
 130         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
 131         # rldicl reg, 1, 35, 0
 132         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
 133         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
 134         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
 135
 136     def test_ROTL32(self):
 137         # r1 = 0xdeadbeef
 138         value = 0xdeadbeef
 139
 140         # rlwinm reg, 1, 10, 0, 31
 141         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
 142         # rlwinm reg, 1, 17, 0, 31
 143         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
 144         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
 145         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
 146
 147     def test_EXTS64(self):
 148         value_a = SelectableInt(0xdeadbeef, 32)  # r1
 149         value_b = SelectableInt(0x73123456, 32)  # r2
 150         value_c = SelectableInt(0x80000000, 32)  # r3
 151
 152         # extswsli reg, 1, 0
 153         self.assertHex(EXTS64(value_a), 0xffffffffdeadbeef)
 154         # extswsli reg, 2, 0
 155         self.assertHex(EXTS64(value_b), SelectableInt(value_b.value, 64))
 156         # extswsli reg, 3, 0
 157         self.assertHex(EXTS64(value_c), 0xffffffff80000000)
 158
 159     def assertHex(self, a, b):
 160         a_val = a
 161         if isinstance(a, SelectableInt):
 162             a_val = a.value
 163         b_val = b
 164         if isinstance(b, SelectableInt):
 165             b_val = b.value
 166         msg = "{:x} != {:x}".format(a_val, b_val)
 167         return self.assertEqual(a, b, msg)
 168
 169
 170 if __name__ == '__main__':
 171     print (SelectableInt.__bases__)
 172     unittest.main()