llvm/compiler-rt/lib/builtins/fp_trunc_impl.inc

//= lib/fp_trunc_impl.inc - high precision -> low precision conversion *-*-===//
//
// 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 a fairly generic conversion from a wider to a narrower
// IEEE-754 floating-point type in the default (round to nearest, ties to even)
// rounding mode.  The constants and types defined following the includes below
// parameterize the conversion.
//
// This routine can be trivially adapted to support conversions to
// half-precision or from quad-precision. It does not support types that don't
// use the usual IEEE-754 interchange formats; specifically, some work would be
// needed to adapt it to (for example) the Intel 80-bit format or PowerPC
// double-double format.
//
// Note please, however, that this implementation is only intended to support
// *narrowing* operations; if you need to convert to a *wider* floating-point
// type (e.g. float -> double), then this routine will not do what you want it
// to.
//
// It also requires that integer types at least as large as both formats
// are available on the target platform; this may pose a problem when trying
// to add support for quad on some 32-bit systems, for example.
//
// Finally, the following assumptions are made:
//
// 1. Floating-point types and integer types have the same endianness on the
//    target platform.
//
// 2. Quiet NaNs, if supported, are indicated by the leading bit of the
//    significand field being set.
//
//===----------------------------------------------------------------------===//

#include "fp_trunc.h"

// The destination type may use a usual IEEE-754 interchange format or Intel
// 80-bit format. In particular, for the destination type dstSigFracBits may be
// not equal to dstSigBits. The source type is assumed to be one of IEEE-754
// standard types.
static __inline dst_t __truncXfYf2__(src_t a) { … }