xref: /aosp_15_r20/external/compiler-rt/lib/builtins/fixxfti.c (revision 7c3d14c8b49c529e04be81a3ce6f5cc23712e4c6)
1*7c3d14c8STreehugger Robot /* ===-- fixxfti.c - Implement __fixxfti -----------------------------------===
2*7c3d14c8STreehugger Robot  *
3*7c3d14c8STreehugger Robot  *      	       The LLVM Compiler Infrastructure
4*7c3d14c8STreehugger Robot  *
5*7c3d14c8STreehugger Robot  * This file is dual licensed under the MIT and the University of Illinois Open
6*7c3d14c8STreehugger Robot  * Source Licenses. See LICENSE.TXT for details.
7*7c3d14c8STreehugger Robot  *
8*7c3d14c8STreehugger Robot  * ===----------------------------------------------------------------------===
9*7c3d14c8STreehugger Robot  *
10*7c3d14c8STreehugger Robot  * This file implements __fixxfti for the compiler_rt library.
11*7c3d14c8STreehugger Robot  *
12*7c3d14c8STreehugger Robot  * ===----------------------------------------------------------------------===
13*7c3d14c8STreehugger Robot  */
14*7c3d14c8STreehugger Robot 
15*7c3d14c8STreehugger Robot #include "int_lib.h"
16*7c3d14c8STreehugger Robot 
17*7c3d14c8STreehugger Robot #ifdef CRT_HAS_128BIT
18*7c3d14c8STreehugger Robot 
19*7c3d14c8STreehugger Robot /* Returns: convert a to a signed long long, rounding toward zero. */
20*7c3d14c8STreehugger Robot 
21*7c3d14c8STreehugger Robot /* Assumption: long double is an intel 80 bit floating point type padded with 6 bytes
22*7c3d14c8STreehugger Robot  *             ti_int is a 128 bit integral type
23*7c3d14c8STreehugger Robot  *             value in long double is representable in ti_int
24*7c3d14c8STreehugger Robot  */
25*7c3d14c8STreehugger Robot 
26*7c3d14c8STreehugger Robot /* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
27*7c3d14c8STreehugger Robot  * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
28*7c3d14c8STreehugger Robot  */
29*7c3d14c8STreehugger Robot 
30*7c3d14c8STreehugger Robot COMPILER_RT_ABI ti_int
__fixxfti(long double a)31*7c3d14c8STreehugger Robot __fixxfti(long double a)
32*7c3d14c8STreehugger Robot {
33*7c3d14c8STreehugger Robot     const ti_int ti_max = (ti_int)((~(tu_int)0) / 2);
34*7c3d14c8STreehugger Robot     const ti_int ti_min = -ti_max - 1;
35*7c3d14c8STreehugger Robot     long_double_bits fb;
36*7c3d14c8STreehugger Robot     fb.f = a;
37*7c3d14c8STreehugger Robot     int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
38*7c3d14c8STreehugger Robot     if (e < 0)
39*7c3d14c8STreehugger Robot         return 0;
40*7c3d14c8STreehugger Robot     ti_int s = -(si_int)((fb.u.high.s.low & 0x00008000) >> 15);
41*7c3d14c8STreehugger Robot     ti_int r = fb.u.low.all;
42*7c3d14c8STreehugger Robot     if ((unsigned)e >= sizeof(ti_int) * CHAR_BIT)
43*7c3d14c8STreehugger Robot         return a > 0 ? ti_max : ti_min;
44*7c3d14c8STreehugger Robot     if (e > 63)
45*7c3d14c8STreehugger Robot         r <<= (e - 63);
46*7c3d14c8STreehugger Robot     else
47*7c3d14c8STreehugger Robot         r >>= (63 - e);
48*7c3d14c8STreehugger Robot     return (r ^ s) - s;
49*7c3d14c8STreehugger Robot }
50*7c3d14c8STreehugger Robot 
51*7c3d14c8STreehugger Robot #endif /* CRT_HAS_128BIT */
52