1//===-- fixxfti.c - Implement __fixxfti -----------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements __fixxfti for the compiler_rt library.
10//
11//===----------------------------------------------------------------------===//
12
13#include "int_lib.h"
14
15#ifdef CRT_HAS_128BIT
16
17// Returns: convert a to a signed long long, rounding toward zero.
18
19// Assumption: long double is an intel 80 bit floating point type padded with 6
20// bytes ti_int is a 128 bit integral type value in long double is representable
21// in ti_int
22
23// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
24// eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
25// mmmm mmmm mmmm
26
27COMPILER_RT_ABI ti_int __fixxfti(long double a) {
28  const ti_int ti_max = (ti_int)((~(tu_int)0) / 2);
29  const ti_int ti_min = -ti_max - 1;
30  long_double_bits fb;
31  fb.f = a;
32  int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
33  if (e < 0)
34    return 0;
35  ti_int s = -(si_int)((fb.u.high.s.low & 0x00008000) >> 15);
36  ti_int r = fb.u.low.all;
37  if ((unsigned)e >= sizeof(ti_int) * CHAR_BIT)
38    return a > 0 ? ti_max : ti_min;
39  if (e > 63)
40    r <<= (e - 63);
41  else
42    r >>= (63 - e);
43  return (r ^ s) - s;
44}
45
46#endif // CRT_HAS_128BIT
47