5f6510825a
This CL fixes all occurences that don't require special OWNER reviews, or can be reviewed by Michi. After this one, we should be able to reenable the readability/check cpplint check. R=mstarzinger@chromium.org Bug: v8:6837, v8:6921 Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng;master.tryserver.v8:v8_linux_noi18n_rel_ng Change-Id: Ic81d68d5534eaa795b7197fed5c41ed158361d62 Reviewed-on: https://chromium-review.googlesource.com/721120 Commit-Queue: Clemens Hammacher <clemensh@chromium.org> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org> Cr-Commit-Position: refs/heads/master@{#48670}
100 lines
2.5 KiB
C++
100 lines
2.5 KiB
C++
// Copyright 2011 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_DIY_FP_H_
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#define V8_DIY_FP_H_
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#include <stdint.h>
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#include "src/base/logging.h"
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namespace v8 {
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namespace internal {
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// This "Do It Yourself Floating Point" class implements a floating-point number
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// with a uint64 significand and an int exponent. Normalized DiyFp numbers will
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// have the most significant bit of the significand set.
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// Multiplication and Subtraction do not normalize their results.
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// DiyFp are not designed to contain special doubles (NaN and Infinity).
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class DiyFp {
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public:
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static const int kSignificandSize = 64;
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DiyFp() : f_(0), e_(0) {}
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DiyFp(uint64_t f, int e) : f_(f), e_(e) {}
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// this = this - other.
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// The exponents of both numbers must be the same and the significand of this
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// must be bigger than the significand of other.
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// The result will not be normalized.
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void Subtract(const DiyFp& other) {
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DCHECK(e_ == other.e_);
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DCHECK(f_ >= other.f_);
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f_ -= other.f_;
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}
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// Returns a - b.
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// The exponents of both numbers must be the same and this must be bigger
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// than other. The result will not be normalized.
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static DiyFp Minus(const DiyFp& a, const DiyFp& b) {
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DiyFp result = a;
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result.Subtract(b);
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return result;
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}
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// this = this * other.
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void Multiply(const DiyFp& other);
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// returns a * b;
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static DiyFp Times(const DiyFp& a, const DiyFp& b) {
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DiyFp result = a;
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result.Multiply(b);
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return result;
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}
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void Normalize() {
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DCHECK_NE(f_, 0);
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uint64_t f = f_;
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int e = e_;
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// This method is mainly called for normalizing boundaries. In general
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// boundaries need to be shifted by 10 bits. We thus optimize for this case.
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const uint64_t k10MSBits = static_cast<uint64_t>(0x3FF) << 54;
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while ((f & k10MSBits) == 0) {
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f <<= 10;
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e -= 10;
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}
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while ((f & kUint64MSB) == 0) {
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f <<= 1;
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e--;
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}
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f_ = f;
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e_ = e;
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}
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static DiyFp Normalize(const DiyFp& a) {
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DiyFp result = a;
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result.Normalize();
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return result;
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}
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uint64_t f() const { return f_; }
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int e() const { return e_; }
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void set_f(uint64_t new_value) { f_ = new_value; }
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void set_e(int new_value) { e_ = new_value; }
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private:
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static const uint64_t kUint64MSB = static_cast<uint64_t>(1) << 63;
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uint64_t f_;
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int e_;
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};
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} // namespace internal
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} // namespace v8
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#endif // V8_DIY_FP_H_
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