src/openpower/util.py

   1 import random
   2 from openpower.consts import FastRegsEnum
   3 from openpower.decoder.power_enums import SPRfull as SPR, spr_dict
   4
   5 # note that we can get away with using SPRfull here because the values
   6 # (numerical values) are what is used for lookup.
   7 spr_to_fast = { SPR.CTR: FastRegsEnum.CTR,
   8                 SPR.LR: FastRegsEnum.LR,
   9                 SPR.TAR: FastRegsEnum.TAR,
  10                 SPR.SRR0: FastRegsEnum.SRR0,
  11                 SPR.SRR1: FastRegsEnum.SRR1,
  12                 SPR.XER: FastRegsEnum.XER,
  13                 SPR.DEC: FastRegsEnum.DEC,
  14                 SPR.TB: FastRegsEnum.TB,
  15                }
  16
  17 sprstr_to_fast = {}
  18 fast_to_spr = {}
  19 for (k, v) in spr_to_fast.items():
  20     sprstr_to_fast[k.name] = v
  21     fast_to_spr[v] = k
  22
  23 def fast_reg_to_spr(spr_num):
  24     return fast_to_spr[spr_num].value
  25
  26
  27 def spr_to_fast_reg(spr_num):
  28     if not isinstance(spr_num, str):
  29         spr_num = spr_dict[spr_num].SPR
  30     return sprstr_to_fast.get(spr_num, None)
  31
  32
  33 def slow_reg_to_spr(slow_reg):
  34     for i, x in enumerate(SPR):
  35         if slow_reg == i:
  36             return x.value
  37
  38
  39 def spr_to_slow_reg(spr_num):
  40     for i, x in enumerate(SPR):
  41         if spr_num == x.value:
  42             return i
  43
  44
  45 # TODO: make this a util routine (somewhere)
  46 def mask_extend(x, nbits, repeat):
  47     res = 0
  48     extended = (1<<repeat)-1
  49     for i in range(nbits):
  50         if x & (1<<i):
  51             res |= extended << (i*repeat)
  52     return res
  53
  54
  55 # makes a logarithmically-skewed random number
  56 def log_rand(n, min_val=1):
  57     logrange = random.randint(1, n)
  58     return random.randint(min_val, (1 << logrange)-1)