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 ROTL64(value, bits):
  10     mask = (1 << 64) - 1
  11     bits = bits & 63
  12     return ((value << bits) | (value >> (64-bits))) & mask
  13
  14 def mask(x, y):
  15     if x < y:
  16         x = 64-x
  17         y = 63-y
  18         mask_a = ((1<<x) - 1) & ((1<<64) - 1)
  19         mask_b = ((1<<y) - 1) & ((1<<64) - 1)
  20     else:
  21         x = 64-x
  22         y = 63-y
  23         mask_a = ((1<<x) - 1) & ((1<<64) - 1)
  24         mask_b = (~((1<<y) - 1)) & ((1<<64) - 1)
  25     return mask_a ^ mask_b
  26
  27
  28 class HelperTests(unittest.TestCase):
  29     def test_mask(self):
  30         # Verified using rlwinm, rldicl, rldicr in qemu
  31         # rlwinm reg, 0, 5, 15
  32         self.assertHex(mask(5+32, 15+32), 0x7ff0000)
  33         # rlwinm reg, 0, 15, 5
  34         self.assertHex(mask(15+32, 5+32), 0xfffffffffc01ffff)
  35         self.assertHex(mask(30+32, 2+32), 0xffffffffe0000003)
  36         # rldicl reg, 0, 37
  37         self.assertHex(mask(37, 63), 0x7ffffff)
  38         self.assertHex(mask(10, 63), 0x3fffffffffffff)
  39         self.assertHex(mask(58, 63), 0x3f)
  40         # rldicr reg, 0, 37
  41         self.assertHex(mask(0, 37), 0xfffffffffc000000)
  42         self.assertHex(mask(0, 10), 0xffe0000000000000)
  43         self.assertHex(mask(0, 58), 0xffffffffffffffe0)
  44     def assertHex(self, a, b):
  45         msg = "{:x} != {:x}".format(a, b)
  46         return self.assertEqual(a, b, msg)
  47
  48 if __name__ == '__main__':
  49     unittest.main()