llvm-project
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1//===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===//
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 integer to double-precision conversion for the
10// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
11// mode.
12//
13//===----------------------------------------------------------------------===//
14
15#define DOUBLE_PRECISION16#include "fp_lib.h"17
18#include "int_lib.h"19
20COMPILER_RT_ABI fp_t __floatsidf(si_int a) {21
22const int aWidth = sizeof a * CHAR_BIT;23
24// Handle zero as a special case to protect clz25if (a == 0)26return fromRep(0);27
28// All other cases begin by extracting the sign and absolute value of a29rep_t sign = 0;30su_int aAbs = (su_int)a;31if (a < 0) {32sign = signBit;33aAbs = -aAbs;34}35
36// Exponent of (fp_t)a is the width of abs(a).37const int exponent = (aWidth - 1) - clzsi(aAbs);38rep_t result;39
40// Shift a into the significand field and clear the implicit bit. Extra41// cast to unsigned int is necessary to get the correct behavior for42// the input INT_MIN.43const int shift = significandBits - exponent;44result = (rep_t)aAbs << shift ^ implicitBit;45
46// Insert the exponent47result += (rep_t)(exponent + exponentBias) << significandBits;48// Insert the sign bit and return49return fromRep(result | sign);50}
51
52#if defined(__ARM_EABI__)53#if defined(COMPILER_RT_ARMHF_TARGET)54AEABI_RTABI fp_t __aeabi_i2d(si_int a) { return __floatsidf(a); }55#else56COMPILER_RT_ALIAS(__floatsidf, __aeabi_i2d)57#endif58#endif59