src/soc/decoder/helpers.py

   1 import unittest
   2 def exts(value, bits):
   3     sign = 1 << (bits - 1)
   4     return (value * (sign - 1)) - (value * sign)
   5
   6 def EXTS64(value):
   7     return exts(value, 64) & ((1<<64)-1)
   8
   9 def rotl(value, bits, wordlen):
  10     mask = (1 << wordlen) - 1
  11     bits = bits & (wordlen - 1)
  12     return ((value << bits) | (value >> (wordlen-bits))) & mask
  13
  14 def ROTL64(value, bits):
  15     return rotl(value, bits, 64)
  16
  17 def ROTL32(value, bits):
  18     return rotl(value, bits, 32)
  19
  20 def MASK(x, y):
  21     if x < y:
  22         x = 64-x
  23         y = 63-y
  24         mask_a = ((1<<x) - 1) & ((1<<64) - 1)
  25         mask_b = ((1<<y) - 1) & ((1<<64) - 1)
  26     else:
  27         x = 64-x
  28         y = 63-y
  29         mask_a = ((1<<x) - 1) & ((1<<64) - 1)
  30         mask_b = (~((1<<y) - 1)) & ((1<<64) - 1)
  31     return mask_a ^ mask_b
  32
  33
  34 class HelperTests(unittest.TestCase):
  35     def test_MASK(self):
  36         # Verified using rlwinm, rldicl, rldicr in qemu
  37         # li 1, -1
  38         # rlwinm reg, 1, 0, 5, 15
  39         self.assertHex(MASK(5+32, 15+32), 0x7ff0000)
  40         # rlwinm reg, 1, 0, 15, 5
  41         self.assertHex(MASK(15+32, 5+32), 0xfffffffffc01ffff)
  42         self.assertHex(MASK(30+32, 2+32), 0xffffffffe0000003)
  43         # rldicl reg, 1, 0, 37
  44         self.assertHex(MASK(37, 63), 0x7ffffff)
  45         self.assertHex(MASK(10, 63), 0x3fffffffffffff)
  46         self.assertHex(MASK(58, 63), 0x3f)
  47         # rldicr reg, 1, 0, 37
  48         self.assertHex(MASK(0, 37), 0xfffffffffc000000)
  49         self.assertHex(MASK(0, 10), 0xffe0000000000000)
  50         self.assertHex(MASK(0, 58), 0xffffffffffffffe0)
  51
  52     def test_ROTL64(self):
  53         # r1 = 0xdeadbeef12345678
  54         value = 0xdeadbeef12345678
  55
  56         # rldicl reg, 1, 10, 0
  57         self.assertHex(ROTL64(value, 10), 0xb6fbbc48d159e37a)
  58         # rldicl reg, 1, 35, 0
  59         self.assertHex(ROTL64(value, 35), 0x91a2b3c6f56df778)
  60         self.assertHex(ROTL64(value, 58), 0xe37ab6fbbc48d159)
  61         self.assertHex(ROTL64(value, 22), 0xbbc48d159e37ab6f)
  62
  63     def test_ROTL32(self):
  64         # r1 = 0xdeadbeef
  65         value = 0xdeadbeef
  66
  67         # rlwinm reg, 1, 10, 0, 31
  68         self.assertHex(ROTL32(value, 10), 0xb6fbbf7a)
  69         # rlwinm reg, 1, 17, 0, 31
  70         self.assertHex(ROTL32(value, 17), 0x7ddfbd5b)
  71         self.assertHex(ROTL32(value, 25), 0xdfbd5b7d)
  72         self.assertHex(ROTL32(value, 30), 0xf7ab6fbb)
  73
  74     def assertHex(self, a, b):
  75         msg = "{:x} != {:x}".format(a, b)
  76         return self.assertEqual(a, b, msg)
  77
  78 if __name__ == '__main__':
  79     unittest.main()