src/nmutil/divmod.py

   1 from copy import copy
   2 # this is a POWER ISA 3.0B compatible *signed* div function
   3 # however it is also the c, c++, rust, java *and* x86 way of doing things
   4 def trunc_divs(n, d):
   5     abs_n = abs(n.to_signed_int())
   6     abs_d = abs(d.to_signed_int())
   7     print("trunc_div n", abs_n, n.to_signed_int())
   8     print("trunc_div d", abs_d, d.to_signed_int())
   9     abs_q = abs_n // abs_d
  10     sign_n = n.value & (1 << (n.bits - 1)) != 0
  11     sign_d = d.value & (1 << (d.bits - 1)) != 0
  12     print ("trunc_div", hex(n.value), hex(d.value),
  13                         hex(abs_n), hex(abs_d), hex(abs_q),
  14                         sign_n, sign_d)
  15     res = copy(n)
  16     if (sign_n == sign_d):
  17         res.value = abs_q
  18         return res
  19     mask = (1 << res.bits) - 1
  20     res.value = (-abs_q) & mask
  21
  22     return res
  23
  24
  25 # this is a POWER ISA 3.0B compatible *signed* mod / remainder function
  26 # however it is also the c, c++, rust, java *and* x86 way of doing things
  27 def trunc_rems(n, d):
  28     m = d * trunc_divs(n, d)
  29     m.bits = n.bits # cheat - really shouldn't do this. mul returns full length
  30     return n - m
  31
  32