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 27 COMPILER_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