Class: LFSR::Fast::Size31

Inherits:
LFSR_Base
  • Object
show all
Defined in:
ext/lfsr/lfsr.c

Constant Summary collapse

MASK = 
ULL2NUM(0x7fffffffLLU)

Instance Method Summary collapse

Instance Method Details

#next_i ⇒ Object 



355
356
357
358
359
360
361
362
363
364
365
 
# File 'ext/lfsr/lfsr.c', line 355

VALUE rb_lfsr_next_i_31(VALUE self) {
  unsigned long long reg = NUM2ULL(ROBJECT(self)->as.ary[0]), max = NUM2ULL(ROBJECT(self)->as.ary[1]);

  label_shift31:
  reg = (reg >> 1) | ((bit(0)^bit(1)^bit(2)^bit(3)) << 0x1e);
  if (reg > max) goto label_shift31;

  ROBJECT(self)->as.ary[0] = ULL2NUM(reg);

  return ULL2NUM(reg - 1);
}