none/tests/s390x/rounding-1.c

   1 #include <stdlib.h>
   2 #include <assert.h>
   3 #include <stdio.h>
   4 #include <stdint.h>
   5 #include <inttypes.h>
   6
   7 /* This testcase is to illustrate that for convert to fixed the condition
   8    code depends on the rounding mode. */
   9
  10 const char *
  11 rtext(unsigned round)
  12 {
  13    switch (round) {
  14    case 0: return "[fpc]";
  15    case 1: return "[->near/away]";
  16       /* 2 is invalid */
  17    case 3: return "[prep short]";
  18    case 4: return "[->near/even]";
  19    case 5: return "[->0]";
  20    case 6: return "[->+inf]";
  21    case 7: return "[->-inf]";
  22    }
  23    assert(0);
  24 }
  25
  26 #define convert_to_int(opcode,src_type,dst_type,dst_fmt,round,value) \
  27 do { \
  28    src_type src = value; \
  29    dst_type dst;         \
  30    unsigned cc;          \
  31                          \
  32    __asm__ volatile (opcode " %[dst]," #round ",%[src]\n\t"     \
  33                      "ipm %[cc]\n\t"                  \
  34                      "srl %[cc],28\n\t"               \
  35                      : [dst] "=d"(dst), [cc] "=d"(cc) \
  36                      : [src] "f"(src)                 \
  37                      : "cc");                         \
  38                                                       \
  39    printf("%s %-20s %f\t-> %"dst_fmt"\tcc = %u\n",    \
  40           opcode, rtext(round), src, dst, cc);        \
  41 } while (0)
  42
  43
  44 #define cfdbr(round,value) \
  45         convert_to_int("cfdbr",double,int32_t,PRId32,round,value)
  46
  47 int main(void)
  48 {
  49    double dval;
  50
  51    dval = -2147483648.5;  // a < MN
  52
  53    // f64 -> i32
  54
  55    cfdbr(4, dval);  // round to nearest with ties to even
  56    cfdbr(5, dval);  // round to zero
  57    cfdbr(6, dval);  // round to +inf
  58
  59    /* The next invocation needs to give cc=3. It used to give cc=1 when
  60       we were considering the to-be-converted value ONLY */
  61    cfdbr(7, dval);  // round to -inf
  62
  63    return 0;
  64 }