//===-- aarch64 floating point env manipulation functions -------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
#include "src/__support/macros/attributes.h" // LIBC_INLINE
#include "src/__support/macros/config.h"
#include "src/__support/macros/properties/architectures.h"
#if !defined(LIBC_TARGET_ARCH_IS_AARCH64) || defined(__APPLE__)
#error "Invalid include"
#endif
#include <arm_acle.h>
#include <stdint.h>
#include "hdr/fenv_macros.h"
#include "hdr/types/fenv_t.h"
#include "src/__support/FPUtil/FPBits.h"
namespace LIBC_NAMESPACE_DECL {
namespace fputil {
struct FEnv {
struct FPState {
uint32_t ControlWord;
uint32_t StatusWord;
};
static_assert(
sizeof(fenv_t) == sizeof(FPState),
"Internal floating point state does not match the public fenv_t type.");
static constexpr uint32_t TONEAREST = 0x0;
static constexpr uint32_t UPWARD = 0x1;
static constexpr uint32_t DOWNWARD = 0x2;
static constexpr uint32_t TOWARDZERO = 0x3;
static constexpr uint32_t INVALID = 0x1;
static constexpr uint32_t DIVBYZERO = 0x2;
static constexpr uint32_t OVERFLOW = 0x4;
static constexpr uint32_t UNDERFLOW = 0x8;
static constexpr uint32_t INEXACT = 0x10;
// Zero-th bit is the first bit.
static constexpr uint32_t RoundingControlBitPosition = 22;
static constexpr uint32_t ExceptionStatusFlagsBitPosition = 0;
static constexpr uint32_t ExceptionControlFlagsBitPosition = 8;
LIBC_INLINE static uint32_t getStatusValueForExcept(int excepts) {
return ((excepts & FE_INVALID) ? INVALID : 0) |
((excepts & FE_DIVBYZERO) ? DIVBYZERO : 0) |
((excepts & FE_OVERFLOW) ? OVERFLOW : 0) |
((excepts & FE_UNDERFLOW) ? UNDERFLOW : 0) |
((excepts & FE_INEXACT) ? INEXACT : 0);
}
LIBC_INLINE static int exceptionStatusToMacro(uint32_t status) {
return ((status & INVALID) ? FE_INVALID : 0) |
((status & DIVBYZERO) ? FE_DIVBYZERO : 0) |
((status & OVERFLOW) ? FE_OVERFLOW : 0) |
((status & UNDERFLOW) ? FE_UNDERFLOW : 0) |
((status & INEXACT) ? FE_INEXACT : 0);
}
static uint32_t getControlWord() {
#ifdef __clang__
// GCC does not currently support __arm_rsr.
return __arm_rsr("fpcr");
#else
return __builtin_aarch64_get_fpcr();
#endif
}
static void writeControlWord(uint32_t fpcr) {
#ifdef __clang__
// GCC does not currently support __arm_wsr.
__arm_wsr("fpcr", fpcr);
#else
__builtin_aarch64_set_fpcr(fpcr);
#endif
}
static uint32_t getStatusWord() {
#ifdef __clang__
return __arm_rsr("fpsr");
#else
return __builtin_aarch64_get_fpsr();
#endif
}
static void writeStatusWord(uint32_t fpsr) {
#ifdef __clang__
__arm_wsr("fpsr", fpsr);
#else
__builtin_aarch64_set_fpsr(fpsr);
#endif
}
};
LIBC_INLINE int enable_except(int excepts) {
uint32_t newExcepts = FEnv::getStatusValueForExcept(excepts);
uint32_t controlWord = FEnv::getControlWord();
int oldExcepts =
(controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
controlWord |= (newExcepts << FEnv::ExceptionControlFlagsBitPosition);
FEnv::writeControlWord(controlWord);
return FEnv::exceptionStatusToMacro(oldExcepts);
}
LIBC_INLINE int disable_except(int excepts) {
uint32_t disabledExcepts = FEnv::getStatusValueForExcept(excepts);
uint32_t controlWord = FEnv::getControlWord();
int oldExcepts =
(controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
controlWord &= ~(disabledExcepts << FEnv::ExceptionControlFlagsBitPosition);
FEnv::writeControlWord(controlWord);
return FEnv::exceptionStatusToMacro(oldExcepts);
}
LIBC_INLINE int get_except() {
uint32_t controlWord = FEnv::getControlWord();
int enabledExcepts =
(controlWord >> FEnv::ExceptionControlFlagsBitPosition) & 0x1F;
return FEnv::exceptionStatusToMacro(enabledExcepts);
}
LIBC_INLINE int clear_except(int excepts) {
uint32_t statusWord = FEnv::getStatusWord();
uint32_t toClear = FEnv::getStatusValueForExcept(excepts);
statusWord &= ~(toClear << FEnv::ExceptionStatusFlagsBitPosition);
FEnv::writeStatusWord(statusWord);
return 0;
}
LIBC_INLINE int test_except(int excepts) {
uint32_t toTest = FEnv::getStatusValueForExcept(excepts);
uint32_t statusWord = FEnv::getStatusWord();
return FEnv::exceptionStatusToMacro(
(statusWord >> FEnv::ExceptionStatusFlagsBitPosition) & toTest);
}
LIBC_INLINE int set_except(int excepts) {
uint32_t statusWord = FEnv::getStatusWord();
uint32_t statusValue = FEnv::getStatusValueForExcept(excepts);
statusWord |= (statusValue << FEnv::ExceptionStatusFlagsBitPosition);
FEnv::writeStatusWord(statusWord);
return 0;
}
LIBC_INLINE int raise_except(int excepts) {
float zero = 0.0f;
float one = 1.0f;
float largeValue = FPBits<float>::max_normal().get_val();
float smallValue = FPBits<float>::min_normal().get_val();
auto divfunc = [](float a, float b) {
__asm__ __volatile__("ldr s0, %0\n\t"
"ldr s1, %1\n\t"
"fdiv s0, s0, s1\n\t"
: // No outputs
: "m"(a), "m"(b)
: "s0", "s1" /* s0 and s1 are clobbered */);
};
uint32_t toRaise = FEnv::getStatusValueForExcept(excepts);
int result = 0;
if (toRaise & FEnv::INVALID) {
divfunc(zero, zero);
uint32_t statusWord = FEnv::getStatusWord();
if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
FEnv::INVALID))
result = -1;
}
if (toRaise & FEnv::DIVBYZERO) {
divfunc(one, zero);
uint32_t statusWord = FEnv::getStatusWord();
if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
FEnv::DIVBYZERO))
result = -1;
}
if (toRaise & FEnv::OVERFLOW) {
divfunc(largeValue, smallValue);
uint32_t statusWord = FEnv::getStatusWord();
if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
FEnv::OVERFLOW))
result = -1;
}
if (toRaise & FEnv::UNDERFLOW) {
divfunc(smallValue, largeValue);
uint32_t statusWord = FEnv::getStatusWord();
if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
FEnv::UNDERFLOW))
result = -1;
}
if (toRaise & FEnv::INEXACT) {
float two = 2.0f;
float three = 3.0f;
// 2.0 / 3.0 cannot be represented exactly in any radix 2 floating point
// format.
divfunc(two, three);
uint32_t statusWord = FEnv::getStatusWord();
if (!((statusWord >> FEnv::ExceptionStatusFlagsBitPosition) &
FEnv::INEXACT))
result = -1;
}
return result;
}
LIBC_INLINE int get_round() {
uint32_t roundingMode =
(FEnv::getControlWord() >> FEnv::RoundingControlBitPosition) & 0x3;
switch (roundingMode) {
case FEnv::TONEAREST:
return FE_TONEAREST;
case FEnv::DOWNWARD:
return FE_DOWNWARD;
case FEnv::UPWARD:
return FE_UPWARD;
case FEnv::TOWARDZERO:
return FE_TOWARDZERO;
default:
return -1; // Error value.
}
}
LIBC_INLINE int set_round(int mode) {
uint16_t bitValue;
switch (mode) {
case FE_TONEAREST:
bitValue = FEnv::TONEAREST;
break;
case FE_DOWNWARD:
bitValue = FEnv::DOWNWARD;
break;
case FE_UPWARD:
bitValue = FEnv::UPWARD;
break;
case FE_TOWARDZERO:
bitValue = FEnv::TOWARDZERO;
break;
default:
return 1; // To indicate failure
}
uint32_t controlWord = FEnv::getControlWord();
controlWord &= ~(0x3 << FEnv::RoundingControlBitPosition);
controlWord |= (bitValue << FEnv::RoundingControlBitPosition);
FEnv::writeControlWord(controlWord);
return 0;
}
LIBC_INLINE int get_env(fenv_t *envp) {
FEnv::FPState *state = reinterpret_cast<FEnv::FPState *>(envp);
state->ControlWord = FEnv::getControlWord();
state->StatusWord = FEnv::getStatusWord();
return 0;
}
LIBC_INLINE int set_env(const fenv_t *envp) {
if (envp == FE_DFL_ENV) {
// Default status and control words bits are all zeros so we just
// write zeros.
FEnv::writeStatusWord(0);
FEnv::writeControlWord(0);
return 0;
}
const FEnv::FPState *state = reinterpret_cast<const FEnv::FPState *>(envp);
FEnv::writeControlWord(state->ControlWord);
FEnv::writeStatusWord(state->StatusWord);
return 0;
}
} // namespace fputil
} // namespace LIBC_NAMESPACE_DECL
#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_AARCH64_FENVIMPL_H
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