| __extension__ union { double d; int i[2]; } u = { d: -0.25 }; |
| |
| /* This assumes the endianness of words in a long long is the same as |
| that for doubles, which doesn't hold for a few platforms, but we |
| can probably special case them here, as appropriate. */ |
| long long endianness_test = 1; |
| #define MSW (*(int*)&endianness_test) |
| |
| int |
| signbit(double x) |
| { |
| __extension__ union { double d; int i[2]; } u = { d: x }; |
| return u.i[MSW] < 0; |
| } |
| |
| int main(void) |
| { |
| if (2*sizeof(int) != sizeof(double) || u.i[MSW] >= 0) |
| exit(0); |
| |
| if (!signbit(-0.25)) |
| abort(); |
| |
| exit(0); |
| } |