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1//===-- Division of IEEE 754 floating-point numbers -------------*- 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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_DIV_H10#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_DIV_H11 12#include "hdr/errno_macros.h"13#include "hdr/fenv_macros.h"14#include "src/__support/CPP/algorithm.h"15#include "src/__support/CPP/bit.h"16#include "src/__support/CPP/type_traits.h"17#include "src/__support/FPUtil/BasicOperations.h"18#include "src/__support/FPUtil/FEnvImpl.h"19#include "src/__support/FPUtil/FPBits.h"20#include "src/__support/FPUtil/dyadic_float.h"21#include "src/__support/macros/attributes.h"22#include "src/__support/macros/config.h"23#include "src/__support/macros/optimization.h"24 25namespace LIBC_NAMESPACE_DECL {26namespace fputil::generic {27 28template <typename OutType, typename InType>29LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> &&30 cpp::is_floating_point_v<InType> &&31 sizeof(OutType) <= sizeof(InType),32 OutType>33div(InType x, InType y) {34 using OutFPBits = FPBits<OutType>;35 using OutStorageType = typename OutFPBits::StorageType;36 using InFPBits = FPBits<InType>;37 using InStorageType = typename InFPBits::StorageType;38 using DyadicFloat = DyadicFloat<cpp::max(39 static_cast<size_t>(16),40 cpp::bit_ceil(static_cast<size_t>(InFPBits::SIG_LEN + 1)))>;41 42 InFPBits x_bits(x);43 InFPBits y_bits(y);44 45 Sign result_sign = x_bits.sign() == y_bits.sign() ? Sign::POS : Sign::NEG;46 47 if (LIBC_UNLIKELY(x_bits.is_inf_or_nan() || y_bits.is_inf_or_nan() ||48 x_bits.is_zero() || y_bits.is_zero())) {49 if (x_bits.is_nan() || y_bits.is_nan()) {50 if (x_bits.is_signaling_nan() || y_bits.is_signaling_nan())51 raise_except_if_required(FE_INVALID);52 53 if (x_bits.is_quiet_nan()) {54 InStorageType x_payload = x_bits.get_mantissa();55 x_payload >>= InFPBits::FRACTION_LEN - OutFPBits::FRACTION_LEN;56 return OutFPBits::quiet_nan(x_bits.sign(),57 static_cast<OutStorageType>(x_payload))58 .get_val();59 }60 61 if (y_bits.is_quiet_nan()) {62 InStorageType y_payload = y_bits.get_mantissa();63 y_payload >>= InFPBits::FRACTION_LEN - OutFPBits::FRACTION_LEN;64 return OutFPBits::quiet_nan(y_bits.sign(),65 static_cast<OutStorageType>(y_payload))66 .get_val();67 }68 69 return OutFPBits::quiet_nan().get_val();70 }71 72 if (x_bits.is_inf()) {73 if (y_bits.is_inf()) {74 set_errno_if_required(EDOM);75 raise_except_if_required(FE_INVALID);76 return OutFPBits::quiet_nan().get_val();77 }78 79 return OutFPBits::inf(result_sign).get_val();80 }81 82 if (y_bits.is_inf())83 return OutFPBits::zero(result_sign).get_val();84 85 if (y_bits.is_zero()) {86 if (x_bits.is_zero()) {87 raise_except_if_required(FE_INVALID);88 return OutFPBits::quiet_nan().get_val();89 }90 91 raise_except_if_required(FE_DIVBYZERO);92 return OutFPBits::inf(result_sign).get_val();93 }94 95 if (x_bits.is_zero())96 return OutFPBits::zero(result_sign).get_val();97 }98 99 DyadicFloat xd(x);100 DyadicFloat yd(y);101 102 // Number of iterations = full output precision + 1 rounding bit + 1 potential103 // leading 0.104 constexpr int NUM_ITERS = OutFPBits::FRACTION_LEN + 3;105 int result_exp = xd.exponent - yd.exponent - (NUM_ITERS - 1);106 107 InStorageType q = 0;108 InStorageType r = static_cast<InStorageType>(xd.mantissa >> 2);109 InStorageType yd_mant_in = static_cast<InStorageType>(yd.mantissa >> 1);110 111 for (int i = 0; i < NUM_ITERS; ++i) {112 q <<= 1;113 r <<= 1;114 if (r >= yd_mant_in) {115 q += 1;116 r -= yd_mant_in;117 }118 }119 120 DyadicFloat result(result_sign, result_exp, q);121 result.mantissa |= static_cast<unsigned int>(r != 0);122 return result.template as<OutType, /*ShouldSignalExceptions=*/true>();123}124 125} // namespace fputil::generic126} // namespace LIBC_NAMESPACE_DECL127 128#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_DIV_H129