sdcc/support/regression/tests/modulong.c

   1 /*
   2    modulong.c
   3    A modulo algrithm. The point of this test is that it triggers otherwise untested peephole rules.
   4  */
   5
   6 #include <testfwk.h>
   7
   8 #define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
   9
  10 unsigned long
  11 modulong (unsigned long a, unsigned long b)
  12 {
  13   unsigned char count = 0;
  14
  15   while (!MSB_SET(b))
  16   {
  17      b <<= 1;
  18      if (b > a)
  19      {
  20         b >>=1;
  21         break;
  22      }
  23      count++;
  24   }
  25   do
  26   {
  27     if (a >= b)
  28       a -= b;
  29     b >>= 1;
  30   }
  31   while (count--);
  32
  33   return a;
  34 }
  35
  36 void
  37 testMod(void)
  38 {
  39         ASSERT (modulong (42ul, 23ul) == 42ul % 23ul);
  40 }
  41