floatundixf.c revision 355940
1//===-- floatundixf.c - Implement __floatundixf ---------------------------===// 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 __floatundixf for the compiler_rt library. 10// 11//===----------------------------------------------------------------------===// 12 13#if !_ARCH_PPC 14 15#include "int_lib.h" 16 17// Returns: convert a to a long double, rounding toward even. 18 19// Assumption: long double is a IEEE 80 bit floating point type padded to 128 20// bits du_int is a 64 bit integral type 21 22// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee 23// eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm 24// mmmm mmmm mmmm 25COMPILER_RT_ABI long double __floatundixf(du_int a) { 26 if (a == 0) 27 return 0.0; 28 const unsigned N = sizeof(du_int) * CHAR_BIT; 29 int clz = __builtin_clzll(a); 30 int e = (N - 1) - clz; // exponent 31 long_double_bits fb; 32 fb.u.high.s.low = (e + 16383); // exponent 33 fb.u.low.all = a << clz; // mantissa 34 return fb.f; 35} 36 37#endif // _ARCH_PPC 38