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33 * @(#)fixunsdfdi.c 8.1 (Berkeley) 6/4/93
34 * $FreeBSD: src/lib/libc/quad/fixunsdfdi.c,v 1.3 2007/01/09 00:28:03 imp Exp $
39 #define ONE_FOURTH (1 << (LONG_BITS - 2))
40 #define ONE_HALF (ONE_FOURTH * 2.0)
41 #define ONE (ONE_FOURTH * 4.0)
44 * Convert double to (unsigned) quad.
45 * Not sure what to do with negative numbers---for now, anything out
46 * of range becomes UQUAD_MAX.
49 __fixunsdfdi(double x)
55 return (UQUAD_MAX); /* ??? should be 0? ERANGE??? */
56 #ifdef notdef /* this falls afoul of a GCC bug */
59 #else /* so we wire in 2^64-1 instead */
60 if (x >= 18446744073709551615.0)
64 * Get the upper part of the result. Note that the divide
65 * may round up; we want to avoid this if possible, so we
66 * subtract `1/2' first.
68 toppart = (x - ONE_HALF) / ONE;
70 * Now build a u_quad_t out of the top part. The difference
71 * between x and this is the bottom part (this may introduce
72 * a few fuzzy bits, but what the heck). With any luck this
73 * difference will be nonnegative: x should wind up in the
74 * range [0..ULONG_MAX]. For paranoia, we assume [LONG_MIN..
75 * 2*ULONG_MAX] instead.
77 t.ul[H] = (unsigned long)toppart;