Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame^] | 1 | //===-- fixdfti.c - Implement __fixdfti -----------------------------------===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file implements __fixdfti for the compiler_rt library. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #if __x86_64 |
| 15 | |
| 16 | #include "int_lib.h" |
| 17 | |
| 18 | // Returns: convert a to a signed long long, rounding toward zero. |
| 19 | |
| 20 | // Assumption: double is a IEEE 64 bit floating point type |
| 21 | // su_int is a 32 bit integral type |
| 22 | // value in double is representable in ti_int (no range checking performed) |
| 23 | |
| 24 | // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm |
| 25 | |
| 26 | ti_int |
| 27 | __fixdfti(double a) |
| 28 | { |
| 29 | double_bits fb; |
| 30 | fb.f = a; |
| 31 | int e = ((fb.u.high & 0x7FF00000) >> 20) - 1023; |
| 32 | if (e < 0) |
| 33 | return 0; |
| 34 | ti_int s = (si_int)(fb.u.high & 0x80000000) >> 31; |
| 35 | ti_int r = 0x0010000000000000uLL | (0x000FFFFFFFFFFFFFuLL & fb.u.all); |
| 36 | if (e > 52) |
| 37 | r <<= (e - 52); |
| 38 | else |
| 39 | r >>= (52 - e); |
| 40 | return (r ^ s) - s; |
| 41 | } |
| 42 | |
| 43 | #endif |