src/openpower/util.py

   1 import os
   2 import random
   3 from openpower.consts import FastRegsEnum
   4 from openpower.decoder.power_enums import SPRfull as SPR, spr_dict
   5
   6 # note that we can get away with using SPRfull here because the values
   7 # (numerical values) are what is used for lookup.
   8 spr_to_fast = { SPR.CTR: FastRegsEnum.CTR,
   9                 SPR.LR: FastRegsEnum.LR,
  10                 SPR.TAR: FastRegsEnum.TAR,
  11                 SPR.SRR0: FastRegsEnum.SRR0,
  12                 SPR.SRR1: FastRegsEnum.SRR1,
  13                 SPR.XER: FastRegsEnum.XER,
  14                 SPR.DEC: FastRegsEnum.DEC,
  15                 SPR.TB: FastRegsEnum.TB,
  16                 SPR.SVSRR0: FastRegsEnum.SVSRR0,
  17                }
  18
  19 sprstr_to_fast = {}
  20 fast_to_spr = {}
  21 for (k, v) in spr_to_fast.items():
  22     sprstr_to_fast[k.name] = v
  23     fast_to_spr[v] = k
  24
  25 def fast_reg_to_spr(spr_num):
  26     return fast_to_spr[spr_num].value
  27
  28
  29 def spr_to_fast_reg(spr_num):
  30     if not isinstance(spr_num, str):
  31         spr_num = spr_dict[spr_num].SPR
  32     return sprstr_to_fast.get(spr_num, None)
  33
  34
  35 def slow_reg_to_spr(slow_reg):
  36     for i, x in enumerate(SPR):
  37         if slow_reg == i:
  38             return x.value
  39
  40
  41 def spr_to_slow_reg(spr_num):
  42     for i, x in enumerate(SPR):
  43         if spr_num == x.value:
  44             return i
  45
  46
  47 # TODO: make this a util routine (somewhere)
  48 def mask_extend(x, nbits, repeat):
  49     res = 0
  50     extended = (1<<repeat)-1
  51     for i in range(nbits):
  52         if x & (1<<i):
  53             res |= extended << (i*repeat)
  54     return res
  55
  56
  57 # makes a logarithmically-skewed random number
  58 def log_rand(n, min_val=1):
  59     logrange = random.randint(1, n)
  60     return random.randint(min_val, (1 << logrange)-1)
  61
  62
  63 def log(*args, **kwargs):
  64     """verbose printing, disabled if an ENV VAR "SILENCELOG" exists.
  65     """
  66     if 'SILENCELOG' in os.environ:
  67         return
  68     print(*args, **kwargs)
  69