llvm-project/compiler-rt/lib/builtins/fixunsxfti.c

45 lines
1.4 KiB
C

//===-- fixunsxfti.c - Implement __fixunsxfti -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements __fixunsxfti for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
#ifdef CRT_HAS_128BIT
// Returns: convert a to a unsigned long long, rounding toward zero.
// Negative values all become zero.
// Assumption: long double is an intel 80 bit floating point type padded with 6
// bytes tu_int is a 128 bit integral type value in long double is representable
// in tu_int or is negative
// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
// eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
// mmmm mmmm mmmm
COMPILER_RT_ABI tu_int __fixunsxfti(long double a) {
long_double_bits fb;
fb.f = a;
int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
if (e < 0 || (fb.u.high.s.low & 0x00008000))
return 0;
if ((unsigned)e > sizeof(tu_int) * CHAR_BIT)
return ~(tu_int)0;
tu_int r = fb.u.low.all;
if (e > 63)
r <<= (e - 63);
else
r >>= (63 - e);
return r;
}
#endif // CRT_HAS_128BIT