openpower/sv/grevlut.py

   1 def lut2(imm, a, b):
   2     idx = b << 1 | a
   3     return (imm>>idx) & 1
   4
   5 def dorow(imm8, step_i, chunk_size):
   6     step_o = 0
   7     for j in range(64):
   8         if (j&chunk_size) == 0:
   9            imm = (imm8 & 0b1111)
  10         else:
  11            imm = (imm8>>4)
  12         a = (step_i>>j)&1
  13         b = (step_i>>(j ^ chunk_size))&1
  14         res = lut2(imm, a, b)
  15         #print(j, bin(imm), a, b, res)
  16         step_o |= (res<<j)
  17     #print ("  ", chunk_size, bin(step_o))
  18     return step_o
  19
  20 def grevlut64(RA, RB, imm, iv):
  21     x = RA
  22     if (iv): x = ~x;
  23     shamt = RB & 63;
  24     #print (bin(shamt), bin(63))
  25     for i in range(6):
  26         step = 1<<i
  27         if (shamt & step):
  28             x = dorow(imm, x, step)
  29     return x & ((1<<64)-1)
  30
  31
  32 if __name__ == '__main__':
  33     # answer: 8888888...
  34     RA = 0x5555555555555555
  35     RB = 0b0010
  36     imm = 0b11000110
  37     x = grevlut64(RA, RB, imm, 1)
  38     print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  39
  40     # answer: 80808080...
  41     RB = 0b00110
  42     imm = 0b11000110
  43     x = grevlut64(RA, RB, imm, 1)
  44     print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  45
  46     # answer: 80008000...
  47     RB = 0b01110
  48     imm = 0b11000110
  49     x = grevlut64(RA, RB, imm, 1)
  50     print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  51     print()
  52
  53     # answer: 01010101...
  54     RB = 0b00110
  55     imm = 0b01101100
  56     x = grevlut64(RA, RB, imm, 0)
  57     print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  58
  59     # answer: 00010001...
  60     RB = 0b01110
  61     imm = 0b01101100
  62     x = grevlut64(RA, RB, imm, 0)
  63     print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  64     print()
  65
  66     for RB in range(64):
  67         RA = 0x5555555555555555
  68         imm = 0b11000110
  69         x = grevlut64(RA, RB, imm, 1)
  70         print ("grevlut", hex(RA), bin(RB), bin(imm), hex(x), "\n", bin(x))
  71         # answer: 8888888...