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257 lines
8.2 KiB
257 lines
8.2 KiB
//
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// Copyright (c) 2017 The Khronos Group Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#include "rounding_mode.h"
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#if (defined(__arm__) || defined(__aarch64__))
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#define FPSCR_FZ (1 << 24) // Flush-To-Zero mode
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#define FPSCR_ROUND_MASK (3 << 22) // Rounding mode:
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#define _ARM_FE_FTZ 0x1000000
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#define _ARM_FE_NFTZ 0x0
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#if defined(__aarch64__)
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#define _FPU_GETCW(cw) __asm__("MRS %0,FPCR" : "=r"(cw))
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#define _FPU_SETCW(cw) __asm__("MSR FPCR,%0" : : "ri"(cw))
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#else
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#define _FPU_GETCW(cw) __asm__("VMRS %0,FPSCR" : "=r"(cw))
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#define _FPU_SETCW(cw) __asm__("VMSR FPSCR,%0" : : "ri"(cw))
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#endif
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#endif
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#if (defined(__arm__) || defined(__aarch64__)) && defined(__GNUC__)
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#define _ARM_FE_TONEAREST 0x0
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#define _ARM_FE_UPWARD 0x400000
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#define _ARM_FE_DOWNWARD 0x800000
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#define _ARM_FE_TOWARDZERO 0xc00000
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RoundingMode set_round(RoundingMode r, Type outType)
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{
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static const int flt_rounds[kRoundingModeCount] = {
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_ARM_FE_TONEAREST, _ARM_FE_TONEAREST, _ARM_FE_UPWARD, _ARM_FE_DOWNWARD,
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_ARM_FE_TOWARDZERO
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};
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static const int int_rounds[kRoundingModeCount] = {
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_ARM_FE_TOWARDZERO, _ARM_FE_TONEAREST, _ARM_FE_UPWARD, _ARM_FE_DOWNWARD,
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_ARM_FE_TOWARDZERO
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};
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const int *p = int_rounds;
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if (outType == kfloat || outType == kdouble) p = flt_rounds;
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int fpscr = 0;
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RoundingMode oldRound = get_round();
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_FPU_GETCW(fpscr);
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_FPU_SETCW(p[r] | (fpscr & ~FPSCR_ROUND_MASK));
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return oldRound;
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}
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RoundingMode get_round(void)
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{
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int fpscr;
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int oldRound;
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_FPU_GETCW(fpscr);
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oldRound = (fpscr & FPSCR_ROUND_MASK);
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switch (oldRound)
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{
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case _ARM_FE_TONEAREST: return kRoundToNearestEven;
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case _ARM_FE_UPWARD: return kRoundUp;
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case _ARM_FE_DOWNWARD: return kRoundDown;
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case _ARM_FE_TOWARDZERO: return kRoundTowardZero;
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}
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return kDefaultRoundingMode;
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}
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#elif !(defined(_WIN32) && defined(_MSC_VER))
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RoundingMode set_round(RoundingMode r, Type outType)
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{
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static const int flt_rounds[kRoundingModeCount] = {
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FE_TONEAREST, FE_TONEAREST, FE_UPWARD, FE_DOWNWARD, FE_TOWARDZERO
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};
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static const int int_rounds[kRoundingModeCount] = {
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FE_TOWARDZERO, FE_TONEAREST, FE_UPWARD, FE_DOWNWARD, FE_TOWARDZERO
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};
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const int *p = int_rounds;
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if (outType == kfloat || outType == kdouble) p = flt_rounds;
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int oldRound = fegetround();
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fesetround(p[r]);
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switch (oldRound)
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{
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case FE_TONEAREST: return kRoundToNearestEven;
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case FE_UPWARD: return kRoundUp;
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case FE_DOWNWARD: return kRoundDown;
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case FE_TOWARDZERO: return kRoundTowardZero;
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default: abort(); // ??!
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}
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return kDefaultRoundingMode; // never happens
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}
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RoundingMode get_round(void)
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{
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int oldRound = fegetround();
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switch (oldRound)
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{
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case FE_TONEAREST: return kRoundToNearestEven;
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case FE_UPWARD: return kRoundUp;
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case FE_DOWNWARD: return kRoundDown;
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case FE_TOWARDZERO: return kRoundTowardZero;
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}
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return kDefaultRoundingMode;
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}
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#else
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RoundingMode set_round(RoundingMode r, Type outType)
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{
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static const int flt_rounds[kRoundingModeCount] = { _RC_NEAR, _RC_NEAR,
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_RC_UP, _RC_DOWN,
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_RC_CHOP };
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static const int int_rounds[kRoundingModeCount] = { _RC_CHOP, _RC_NEAR,
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_RC_UP, _RC_DOWN,
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_RC_CHOP };
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const int *p =
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(outType == kfloat || outType == kdouble) ? flt_rounds : int_rounds;
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unsigned int oldRound;
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int err = _controlfp_s(&oldRound, 0, 0); // get rounding mode into oldRound
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if (err)
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{
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vlog_error("\t\tERROR: -- cannot get rounding mode in %s:%d\n",
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__FILE__, __LINE__);
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return kDefaultRoundingMode; // what else never happens
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}
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oldRound &= _MCW_RC;
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RoundingMode old = (oldRound == _RC_NEAR)
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? kRoundToNearestEven
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: (oldRound == _RC_UP) ? kRoundUp
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: (oldRound == _RC_DOWN)
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? kRoundDown
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: (oldRound == _RC_CHOP) ? kRoundTowardZero
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: kDefaultRoundingMode;
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_controlfp_s(&oldRound, p[r], _MCW_RC); // setting new rounding mode
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return old; // returning old rounding mode
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}
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RoundingMode get_round(void)
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{
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unsigned int oldRound;
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int err = _controlfp_s(&oldRound, 0, 0); // get rounding mode into oldRound
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oldRound &= _MCW_RC;
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return (oldRound == _RC_NEAR)
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? kRoundToNearestEven
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: (oldRound == _RC_UP) ? kRoundUp
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: (oldRound == _RC_DOWN)
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? kRoundDown
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: (oldRound == _RC_CHOP) ? kRoundTowardZero
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: kDefaultRoundingMode;
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}
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#endif
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//
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// FlushToZero() sets the host processor into ftz mode. It is intended to have
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// a remote effect on the behavior of the code in basic_test_conversions.c. Some
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// host processors may not support this mode, which case you'll need to do some
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// clamping in software by testing against FLT_MIN or DBL_MIN in that file.
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//
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// Note: IEEE-754 says conversions are basic operations. As such they do *NOT*
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// have the behavior in section 7.5.3 of the OpenCL spec. They *ALWAYS* flush to
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// zero for subnormal inputs or outputs when FTZ mode is on like other basic
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// operators do (e.g. add, subtract, multiply, divide, etc.)
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//
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// Configuring hardware to FTZ mode varies by platform.
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// CAUTION: Some C implementations may also fail to behave properly in this
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// mode.
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//
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// On PowerPC, it is done by setting the FPSCR into non-IEEE mode.
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// On Intel, you can do this by turning on the FZ and DAZ bits in the MXCSR --
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// provided that SSE/SSE2
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// is used for floating point computation! If your OS uses x87, you'll
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// need to figure out how to turn that off for the conversions code in
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// basic_test_conversions.c so that they flush to zero properly.
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// Otherwise, you'll need to add appropriate software clamping to
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// basic_test_conversions.c in which case, these function are at
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// liberty to do nothing.
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//
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#if defined(__i386__) || defined(__x86_64__) || defined(_WIN32)
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#include <xmmintrin.h>
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#elif defined(__PPC__)
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#include <fpu_control.h>
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#endif
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void *FlushToZero(void)
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{
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#if defined(__APPLE__) || defined(__linux__) || defined(_WIN32)
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#if defined(__i386__) || defined(__x86_64__) || defined(_MSC_VER)
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union {
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int i;
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void *p;
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} u = { _mm_getcsr() };
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_mm_setcsr(u.i | 0x8040);
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return u.p;
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#elif defined(__arm__) || defined(__aarch64__)
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int fpscr;
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_FPU_GETCW(fpscr);
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_FPU_SETCW(fpscr | FPSCR_FZ);
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return NULL;
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#elif defined(__PPC__)
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fpu_control_t flags = 0;
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_FPU_GETCW(flags);
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flags |= _FPU_MASK_NI;
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_FPU_SETCW(flags);
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return NULL;
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#else
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#error Unknown arch
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#endif
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#else
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#error Please configure FlushToZero and UnFlushToZero to behave properly on this operating system.
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#endif
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}
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// Undo the effects of FlushToZero above, restoring the host to default
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// behavior, using the information passed in p.
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void UnFlushToZero(void *p)
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{
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#if defined(__APPLE__) || defined(__linux__) || defined(_WIN32)
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#if defined(__i386__) || defined(__x86_64__) || defined(_MSC_VER)
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union {
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void *p;
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int i;
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} u = { p };
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_mm_setcsr(u.i);
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#elif defined(__arm__) || defined(__aarch64__)
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int fpscr;
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_FPU_GETCW(fpscr);
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_FPU_SETCW(fpscr & ~FPSCR_FZ);
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#elif defined(__PPC__)
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fpu_control_t flags = 0;
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_FPU_GETCW(flags);
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flags &= ~_FPU_MASK_NI;
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_FPU_SETCW(flags);
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#else
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#error Unknown arch
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#endif
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#else
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#error Please configure FlushToZero and UnFlushToZero to behave properly on this operating system.
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#endif
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}
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