dolphin/Source/Core/Common/ArmFPURoundMode.cpp

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// Copyright 2021 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include "Common/CommonTypes.h"
#include "Common/FPURoundMode.h"
#ifdef _MSC_VER
#include <intrin.h>
#endif
static u64 GetFPCR()
{
#ifdef _MSC_VER
return _ReadStatusReg(ARM64_FPCR);
#else
u64 fpcr;
__asm__ __volatile__("mrs %0, fpcr" : "=r"(fpcr));
return fpcr;
#endif
}
static void SetFPCR(u64 fpcr)
{
#ifdef _MSC_VER
_WriteStatusReg(ARM64_FPCR, fpcr);
#else
__asm__ __volatile__("msr fpcr, %0" : : "ri"(fpcr));
#endif
}
namespace FPURoundMode
{
static const u64 default_fpcr = GetFPCR();
static u64 saved_fpcr = default_fpcr;
void SetRoundMode(int mode)
{
// We don't need to do anything here since SetSIMDMode is always called after calling this
}
void SetPrecisionMode(PrecisionMode mode)
{
}
void SetSIMDMode(int rounding_mode, bool non_ieee_mode)
{
// Flush-To-Zero (non-IEEE mode: denormal outputs are set to +/- 0)
constexpr u32 FZ = 1 << 24;
// lookup table for FPSCR.RN-to-FPCR.RMode translation
constexpr u32 rounding_mode_table[] = {
(0 << 22), // nearest
(3 << 22), // zero
(1 << 22), // +inf
(2 << 22), // -inf
};
const u64 base = default_fpcr & ~(0b111 << 22);
SetFPCR(base | rounding_mode_table[rounding_mode] | (non_ieee_mode ? FZ : 0));
}
void SaveSIMDState()
{
saved_fpcr = GetFPCR();
}
void LoadSIMDState()
{
SetFPCR(saved_fpcr);
}
void LoadDefaultSIMDState()
{
SetFPCR(default_fpcr);
}
} // namespace FPURoundMode