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Diffstat (limited to 'lib/fixunsdfti.c')
-rw-r--r-- | lib/fixunsdfti.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/fixunsdfti.c b/lib/fixunsdfti.c new file mode 100644 index 000000000..4b88c6f6b --- /dev/null +++ b/lib/fixunsdfti.c @@ -0,0 +1,44 @@ +//===-- fixunsdfti.c - Implement __fixunsdfti -----------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements __fixunsdfti for the compiler_rt library. +// +//===----------------------------------------------------------------------===// + +#if __x86_64 + +#include "int_lib.h" + +// Returns: convert a to a unsigned long long, rounding toward zero. +// Negative values all become zero. + +// Assumption: double is a IEEE 64 bit floating point type +// tu_int is a 64 bit integral type +// value in double is representable in tu_int or is negative +// (no range checking performed) + +// seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm + +tu_int +__fixunsdfti(double a) +{ + double_bits fb; + fb.f = a; + int e = ((fb.u.high & 0x7FF00000) >> 20) - 1023; + if (e < 0 || (fb.u.high & 0x80000000)) + return 0; + tu_int r = 0x0010000000000000uLL | (fb.u.all & 0x000FFFFFFFFFFFFFuLL); + if (e > 52) + r <<= (e - 52); + else + r >>= (52 - e); + return r; +} + +#endif |