llvm-project

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//===-- floatdixf.c - Implement __floatdixf -------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements __floatdixf for the compiler_rt library.
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//
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//===----------------------------------------------------------------------===//
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#if !_ARCH_PPC
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#include "int_lib.h"
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// Returns: convert a to a long double, rounding toward even.
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// Assumption: long double is a IEEE 80 bit floating point type padded to 128
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// bits di_int is a 64 bit integral type
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// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
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// eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
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// mmmm mmmm mmmm
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COMPILER_RT_ABI xf_float __floatdixf(di_int a) {
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  if (a == 0)
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    return 0.0;
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  const unsigned N = sizeof(di_int) * CHAR_BIT;
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  const di_int s = a >> (N - 1);
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  a = (a ^ s) - s;
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  int clz = __builtin_clzll(a);
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  int e = (N - 1) - clz; // exponent
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  xf_bits fb;
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  fb.u.high.s.low = ((su_int)s & 0x00008000) | // sign
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                    (e + 16383);               // exponent
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  fb.u.low.all = a << clz;                     // mantissa
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  return fb.f;
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}
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#endif // !_ARCH_PPC
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