openpower/sv/sbf.py

   1 def sbf(RA, mask=None, zero=False):
   2     RT = RA if mask is not None and not zero else 0
   3     i = 0
   4     # start setting if no predicate or if 1st predicate bit set
   5     setting_mode = mask is None
   6     while i < 16:
   7         bit = 1<<i
   8         if not setting_mode and mask is not None and (mask & bit):
   9             setting_mode = True # back into "setting" mode
  10         if setting_mode and mask is not None and not (mask & bit):
  11             setting_mode = False # disable when no mask bit
  12         if setting_mode:
  13             if RA & bit: # found a bit in rs1: stop setting RT
  14                 setting_mode = False
  15             else:
  16                 RT |= bit
  17         i += 1
  18     return RT
  19
  20 if __name__ == '__main__':
  21      m  = 0b11000011
  22      v3 = 0b10010100 # vmsbf.m v2, v3
  23      v2 = 0b01000011 # v2
  24      RT = sbf(v3, m, zero=True)
  25      print(bin(v3), bin(v2), bin(RT))
  26      v3 = 0b10010100 # vmsbf.m v2, v3
  27      v2 = 0b00000011 # v2 contents
  28      RT = sbf(v3)
  29      print(bin(v3), bin(v2), bin(RT))
  30      v3 = 0b10010101 # vmsbf.m v2, v3
  31      v2 = 0b00000000 # v2
  32      RT = sbf(v3)
  33      print(bin(v3), bin(v2), bin(RT))
  34      v3 = 0b00000000 # vmsbf.m v2, v3
  35      v2 = 0b11111111 # v2
  36      RT = sbf(v3)
  37      print(bin(v3), bin(v2), bin(RT))