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
   7 # note that we can get away with using SPRfull here because the values
   8 # (numerical values) are what is used for lookup.
   9 spr_to_fast = { SPR.CTR: FastRegsEnum.CTR,
  10                 SPR.LR: FastRegsEnum.LR,
  11                 SPR.TAR: FastRegsEnum.TAR,
  12                 SPR.SRR0: FastRegsEnum.SRR0,
  13                 SPR.SRR1: FastRegsEnum.SRR1,
  14                 SPR.XER: FastRegsEnum.XER,
  15                 SPR.DEC: FastRegsEnum.DEC,
  16                 SPR.TB: FastRegsEnum.TB,
  17                 SPR.SVSRR0: FastRegsEnum.SVSRR0,
  18                }
  19
  20 sprstr_to_fast = {}
  21 fast_to_spr = {}
  22 for (k, v) in spr_to_fast.items():
  23     sprstr_to_fast[k.name] = v
  24     fast_to_spr[v] = k
  25
  26 def fast_reg_to_spr(spr_num):
  27     return fast_to_spr[spr_num].value
  28
  29
  30 def spr_to_fast_reg(spr_num):
  31     if not isinstance(spr_num, str):
  32         spr_num = spr_dict[spr_num].SPR
  33     return sprstr_to_fast.get(spr_num, None)
  34
  35
  36 def slow_reg_to_spr(slow_reg):
  37     for i, x in enumerate(SPR):
  38         if slow_reg == i:
  39             return x.value
  40
  41
  42 def spr_to_slow_reg(spr_num):
  43     for i, x in enumerate(SPR):
  44         if spr_num == x.value:
  45             return i
  46
  47
  48 # TODO: make this a util routine (somewhere)
  49 def mask_extend(x, nbits, repeat):
  50     res = 0
  51     extended = (1<<repeat)-1
  52     for i in range(nbits):
  53         if x & (1<<i):
  54             res |= extended << (i*repeat)
  55     return res
  56
  57
  58 # makes a logarithmically-skewed random number
  59 def log_rand(n, min_val=1):
  60     logrange = random.randint(1, n)
  61     return random.randint(min_val, (1 << logrange)-1)
  62
  63
  64 def log(*args, **kwargs):
  65     """verbose printing, disabled if an ENV VAR "SILENCELOG" exists.
  66     """
  67     if 'SILENCELOG' in os.environ:
  68         return
  69     print(*args, **kwargs)
  70